course 1 Flashcards

Question

The cell wall of gram-positive bacteria is made up of what?

Answer 1

cell wall is made up of only peptidoglycans

Answer 2

the cell wall is supplemented with lipopolysaccharide coat.

Answer 3

Prokaryotic flagellum is significantly thinner, it is not covered by a membrane, protein flagellin is present in bacteria as well as archaea

Answer 4

Phototrophic organisms (procaryotes and eucaryotes): they acquire energy from sunlight (photosynthesis) * Chemotrophic organisms (procaryotes and eucaryotes): they acquire energy by the oxidation of chemicals * Lithotrophic organisms (procaryotes): they acquire energy by the oxidation of inorganic chemicals (H2S, Fe2+ * Organotrophic organisms (procaryotes and eucaryotes): they acquire energy by the oxidation of organic chemicals (fermentation, oxidative phosphorylation)

Answer 5

inorganic compounds (CO2) represent a source of carbon

Answer 6

organic compounds (glucose) represent a source of carbon

Answer 7

Bacteria: * chromosomal DNA is not organized in structures similar to nucleosomes * genes without introns * thymine is present in the tRNA * RNA polymerase is simple (4 polypeptides) * fatty acids in membrane lipids are bound to glycerol by ester bond * cell wall from peptidoglycan Archaea: * chromosomal DNA is organized in structures similar to nucleosomes * tRNA and rRNA genes contain introns * thymine is absent in the tRNA * RNA polymerase is complex (more than 8 polypeptides) * fatty acids in membrane lipids are bound to glycerol by ether bond * cell wall from pseudopeptidoglycan

Answer 8

Procaryotic cell: * 1-10 µm * 1000 - 4000 genes * it does not have regular nucleus * non-mitotic division of chromosomes * transcription and translation are not separated * 70S ribosomes * without classical cytoskeleton * more or less without organelles Eukaryotic cell: 5-100 µm 10 000 - 30 000 genes it has a regular nucleus * mitotic division of chromosomes * transcription and translation are separated * 80S ribosomes * cytoskeleton * organelles

Answer 9

Virtually all animal life depends on bacteria for their survival because they possess the genes and enzymes necessary to synthesize vitamin B12 and provide it through the food chain.

Answer 10

Bacteria have a primitive chromosome called a nucleoid – composed of DNA which is double stranded, circular, and supercoiled. Proteins (histone like). Bacterial genes do not have introns. RNA transcription and protein translation occur in the same compartment (ie. there is no nucleus in bacteria only a nuclear region). There is no cytoskeleton in bacteria. Bacteria have ribosomes, each consisting of a small (30S) and a large (50S) subunit. Division is binary and non-sexual (process known as binary fission).

Answer 11

Lag phase - bacteria adapt to growth conditions. They are not dividing. Log phase (also called logarithmic phase or exponential phase) bacterial cell number doubling. Stationary phase - growth reaches a plateau as the number of dying cells equals the number of dividing cells. Death phase - an exponential decrease in the number of living cell.

Answer 12

They have a unique biochemistry eg. Ether lipid cell membrane. They use more sources for energy compared to eukaryotes eg. Ammonia, metal ions, hydrogen gas. First observed in extreme environments eg. Hot springs, salt lakes etc They are important for human microbiota in the gut, mouth and skin. There is no evidence that they can cause a disease

Answer 13

Archaea have chromatin composed of DNA (double stranded, circular, supercoiled) Histones (similar to eukaryotic histones) Introns are present in the genes encoding tRNA and rRNA. RNA transcription and protein translation are similar to eukaryotic processes. There is an actin cytoskeleton in archaea. Archaea have ribosomes, each consisting of a small (30S) and a large (50S) subunit. Archaea reproduce by binary division, fragmentation or budding.

Answer 14

Plasmid is a circular double stranded DNA molecule. Plasmids often carry genes that benefit the survival of the organism. Plasmids encode genes for resistance to antibiotics or heavy metals. Plasmids encode genes for metabolic enzymes involved in nitrogen fixation.

Answer 15

A stretch of DNA from which replication is initiated/started known as an origin of replication (Ori).

Answer 16

Infection of mice by virulent and non-virulent strains of S. pneumoniae - Identified a ´Transforming Principle´

Answer 17

Griffith experiment repeated but with isolated DNA → identified the ´Transforming Principle´ to be DNA.

Answer 18

A process whereby foreign DNA is introduced into another cell by a virus. A virus that infects bacteria is called a bacteriophage. This leads to genetic recombination in bacteria. The bacteriophage can transfer DNA from one bacterium to another bacterium

Answer 19

a transfer of any part of host DNA (only bacterial genes)

Answer 20

1)Bacterium is infected by phage DNA. 2)Phage replicates and bacterial DNA is broken down into pieces. Sometimes a fragment of bacterial DNA is packaged into phage capsid instead of phage DNA. 3)The donor cell lyses and phage carrying bacterial DNA is released to infect a new host cell. 4)DNA in the new host cell become recombined after infection.

Answer 21

the transfer of a particular part of host DNA along with viral genes.

Answer 22

The recipient cell receives a new metabolic ability (from the transferred bacterial genes)

Answer 23

The transfer of genetic material between bacterial cells via: direct cell to cell contact or 2) a bridge-like connection between two cells. It is a method of horizontal gene transfer. It is not sexual reproduction (ie. there is no transfer of gametes). Transferred DNA is known as a transposon/conjugative plasmid. The transferred DNA is often beneficial to the recipient. Benefits may include antibiotic resistance, xenobiotic (chemical) tolerance or the ability to use new metabolites.

Answer 24

An operon is a functional unit of transcription and genetic regulation. It enables organisms (eg. prokaryotes) to regulate gene expression depending on the environmental conditions.

Answer 25

1) Promoter – a nucleotide sequence that enables a gene to be transcribed. The promoter is recognized by RNA polymerase, which then initiates transcription. 2) Operator – a segment of DNA to which a repressor binds. The repressor protein obstructs the RNA polymerase from transcribing the genes. 3) Structural genes – the genes that are regulated within the operon.

Answer 26

The Lac (Lactose) operon The Trp (Tryptophan) operon

Answer 27

By binding of of the enzyme RNA polymerase (RNAP) which binds to the promoter, immediately upstream of the genes.

Answer 28

They code for catabolic enzymes, produced only in presence of substrate = inductive regulation

Answer 29

genes for anabolic enzymes - negative feedback by product of anabolic pathway = repressive regulation

Answer 30

Nucleus: separated from the cytoplasm by nuclear envelope, it contains most of cellular DNA * Cytoplasm: interior of the cell (without the nucleus), most of metabolic reactions of the cell occur here * Plasma membrane: it forms outer boundary of the cell * Cell wall: some eucaryotic cells have rigid cell wall (plants) * Flagell and cilia: some eucaryotic cells

Answer 31

Nuclear envelope (inner & outer membrane ), it bounds nucleus against rest of the cell, nuclear pores are located in nuclear envelope * Nuclear lamina: localized just beneath nuclear envelope (proteins lamins) * Chromatin: linear chromosomes (nucleosomes: DNA & histones), DNA encodes genetic information of the cell * Nucleolus: place of ribosome production, it is not separated from rest of the nucleus by membrane structure Nucleus is the place for DNA replication (DNA→DNA) and for DNA transcription (DNA→RNA).

Answer 32

Plasma membrane serves as a barrier to outer environment. Structure of plasma membrane: lipid bilayer, outer and inner layer can differ as to present lipids

Answer 33

transport of molecules across plasma membrane, attachment of the cell, receiving information from extracellular environment (receptors)

Answer 34

Plasma membrane is involved in (1) import and export of molecules, (2) attachment of cells to other cell or to extracellular matrix, (3) receiving information from the environment and (4) cell movement.

Answer 35

cellulose (microfibrils) hemicellulose (branched polysacharide) pectin (polysacharide)

Answer 36

Cell wall provides the cell with a protection against mechanical damage and pathogens, forms external skeleton of the cell (and thus skeleton of whole plant) and mediates cell-cell interaction)

Answer 37

Flagella: enable movement of eucaryotic cell Cilia: enable movement in the vicinity of eurcaryotic cell

Answer 38

it is similar for both flagellum and cilium, significantly differs from the structure of procaryotic flagellum (it is significantly more complex), microtubules (9 dublets + 2), motor protein dynein

Answer 39

Cytoplasm includes: * Cytosol which is cytoplasm without membrane-bounded organelles, it has rather character of a gel than a solution, many fundamental chemical reactions of the cell occur here * Membrane-bounded organelles Cytoplasm is the place for mRNA translation (RNA →protein).

Answer 40

Cytosol contains: * Ribosomes (80S): ribosome is a complex of RNA and protein molecules , ribosome is the place of mRNA translation * Cytoskeleton: Three types filaments: * microtubules (tubulin) * Intermediate filaments (various proteins: keratins, vimentin, lamins) * actin filaments (actin) Cell cortex (mesh-like structure from actin filaments located beneath plasma membrane) Cytoskeleton gives the cell its shape, its capacity to move and transport signal.

Answer 41

Mitochondria: energy production (ATP) by oxidative phosphorylation * Chloroplasts (only plants): photosynthesis

Answer 42

4 different compartments (matrix, inner membrane, outer membrane and intermembrane space)

Answer 43

ATP production other functions (buffering cytosolic redox potential: decrease of NADH level in cytosol leads to increased NAD+ level in cytosol for glycolysis; plenty of ATP: citrate from mitochondria → cytosol for biosynthesis, e. g. fatty acids; starvation: oxidation of amino acids in mitochondria)

Answer 44

Endoplasmic reticulum: * Smooth endoplasmic reticulum * Rough endoplasmic reticulum * Golgi apparatus: * Transport vesicles Lysosomes Peroxisomes Vacuoles

Answer 45

Endoplasmic reticulum: synthesis of lipids, membrane proteins and synthesis of proteins for export from the cell

Answer 46

Smooth endoplasmic reticulum (without ribosomes): synthesis of fatty acids and phospholipids, detoxification (hepatocytes) modification of proteins: glycosylation

Answer 47

Rough endoplasmic reticulum (with ribosomes): synthesis of membráne proteins and organelle proteins and synthesis of proteins for export modification of proteins: glycosylation, formation of disulfide bonds, chaperones

Answer 48

Golgi apparatus: modification and transport of the molecules produced in the ER modification of protein: glycosylation, phosphorylation, proteolysis

Answer 49

Transport vesicles: material transport within the cell and outside of the cell

Answer 50

contain enzymes for degradation (acid hydrolases) → degradation of substances, acid pH [FIG.] lysosomal diseases: insufficient activity of some of hydrolases leads to the accumulation of substrate * example: Gaucher syndrome (neurological disorders in children)

Answer 51

Peroxisomes: reactions where dangerously reactive hydrogen peroxide is produced and degraded (oxidases, catalase)

Answer 52

Vacuoles (only plants): large membrane-bounded vesicles containing water solutions of substances (ions, saccharides etc.)

Answer 53

Eucaryotic cell separates DNA transcription from RNA translation: processing of RNA transcript by splicing before its translation!

Answer 54

Size of eucaryotic cell: usually 5-100 µm Generally, eucaryotic cell is bigger than procaryotic cell. Shape of eucaryotic cell very diverse: * unicellular eucaryots (protists) * multicellular eucaryots (connected with cell function in organism): e.g. lymphocyte, erythrocyte, hepatocyte, muscle cell, epithelial cell, neuron etc

Answer 55

Eucaryotes exert lower variability in biochemical capabilities, including the capability of acquiring energy, than procaryotes. Essential ways of acquiring energy: * Phototrophic eucaryotes * Chemotrophic eucaryotes: only organotrophic eucaryotes (only procaryotes are lithotrophic) Source of carbon: * Autotrophic eucaryotes * Heterotrophic eucaryotes Dependence on oxygen: * Aerobic eucaryotes * Anaerobic eucaryotes

Answer 56

(1) epithelial tissue, (2) connective tissue, (3) muscles and (4) nervous tissue

Answer 57

passive movement of solvent molecules through a semi permeable membrane o only water passes (not ions) from an environment of low osmotic pressure to an environment of high osmotic pressure

Answer 58

NaCl -> Na+ + Cl- Na2SO4 -> 2Na+ + SO42- KNO3 -> K+ + NO3 NaH2PO4 -> Na+ + H2PO4

Answer 59

product of solubility KS BaSO4 <-> Ba2+ + SO42- KS = [Ba2+] * [SO42-]

Answer 60

Links with polarity – polar molecules will dissolve in water, non-polar will not - Those forming hydrogen bonds are soluble

Answer 61

= polar = hydrophilic = lipophobic

Answer 62

= non-polar = hydrophobic = lipophilic

Answer 63

carboxylic acids with a shorter carbon chain (up to 8C) are polar and thus also hydrophilic o additional chain means that the molecule will be hydrophobic – thus higher fatty acids in blood need to be transported with the help of transport protein - albumin

Answer 64

usually large molecules with one hydrophilic and one hydrophobic part o soaps and detergents o e.g. phospholipids – form bilayers -> membranes, micelles, liposomes

Answer 65

oils in water o TAG - triacylglycerol o carry no dipole moment, carry no electrical charge à insoluble in water o in water lipid droplets will form and float -> droplets come together to minimize their surface exposure

Answer 66

intracellular fluid - main cation = K+ = 140mM – smaller hydration shell than Na2+ -> passes membranes easier o main anion - proteins – large molecules, hold negative charge, cannot escape outside

Answer 67

extracellular fluid– main cation = Na+ = 140mM o main anion = Cl- = 100mM - organic substances -> glucose, amino acids, urea

Answer 68

acids – substances which release hydrogen cations into aqueous solution o HNO3 -> H+ + NO3 - - bases – substances which release hydroxide ions anions OH- o NaOH -> Na+ + OH- - neutralization – mutual reaction between an acid and a base, production of water and salt o NaOH + HNO3 -> NaNO3 + H2O

Answer 69

acid - substances (molecules and ions) that donate H+ to another substance - basic – substances able to accept H+ from another substance - cleavage/loss of a proton turns the acid into a base

Answer 70

strong electrolytes = fully dissociates - strong acids -> HCl, HNO3, H2SO4, HClO4 - strong bases -> NaOH, KOH, Ca(OH)2, Ba(OH)2

Answer 71

solutions that resists pH changes - mixture of weak acid and its conjugate salt

Answer 72

chromatography - liquid, gas -> separation of compounds according to different affinities for mobile and stationary phase

Answer 73

electrophoresis – separation of substances by their ability to move in an electric field

Answer 74

based on weak bond interactions between the studied substance and the different polar phases o mobile phase = nonpolar solvent (acetonitrile, methanol) o stationary phase = polar molecules (silica gel, octadecyl silica) - polar substances will attach to stationary phase and non-polar will travel faster

Answer 75

stationary phase – very small granules (2-5 μm) of silica gel, hydrated silica, which is then modified and silicon groups bind to hydrocarbon chains, forming octadecyl silicone gel - mobile phase - solvent - acetonitrile, methane - detector - HPLC can use Mass spectrometry as a detector - machine construction

Answer 76

The stationary phase is either a liquid fixed on the supporting material or a solid absorbed in the form of a thin layer - Used mainly in the separation of azo dye (benzene nuclei separated by an azo group)

Answer 77

mobile phase formed by inert gases (He, N2, Ar) - analysis of mainly volatile substances - lipids - capillary column - detector – Flame ionizing detector (FID)

Answer 78

fast and effect technique based on the movement of charges particles in an electric field - isoelectric point – value of pH in solution where a zwitterion stops moving in an electric field (e.g. proteins)

Answer 79

sugars which form via photosynthesis in plants o 6 CO2 + 12 H2O -> C6H12O6 + 6 O2 + 6 H2O - simplest monosaccharides have 3 carbons (=triose) -> glyceraldehyde

Answer 80

Monosaccharides belong among hydroxyl derivatives and carbonyl compounds -via functional group - aldose and ketose o aldose - ribose, glucose, mannose (C2 epimer of glucose), galactose (C4 epimer of glucose) o ketose - ribulose, fructose - according to the number of carbon atoms - triose C3, tetrose C4, pentose C5, hexose C6, heptose C7 o pentose - ribose, deoxyribose, ribulose o hexose - glucose, fructose, galactose, mannose

Answer 81

presence of chiral carbon = optical activity

Answer 82

isomers which are mirror images ( L a D enantiomers) D-isomers occur naturally

Answer 83

another carbon is inserted between 1. and 2. carbon atom - epimer – isomers which differ by their OH group orientation around a carbon - galactose and glucose – isomers which differ by their OH group orientation around the 4th carbon o galactose is a C4 epimer of glucose - glucose and mannose – isomers which differ by their OH group orientation around the 2nd carbon o mannose is a C2 epimer of glucose

Answer 84

a dihydroxyacetone that has no chiral carbon (it is still considered a saccharide, even though it cannot be found freely in nature)

Answer 85

-glycogen – branched polysaccharide (animal) o formed by the connection of α-1,4-glycosidic bond and branched α-1,6- glycosidic bond § branching allows faster breakdown of polysaccharide chains o polysaccharide in human -> storage of glucose - starch –amylose and amylopectin o amylose – only linear chain o amylopectin – linear chain, sometimes branched

Answer 86

cellulose – formed by the connection of glucose by β-1,4- glycosidic bound (which human enzymes cannot breakdown) o form tube like structures which connect

Answer 87

Lipids are substances of natural origin - are not water soluble - consist of fatty acids and alcohol - in the body, they are synthesized from acetyl-coenzyme A (acetyl-CoA) - hydrolyzable lipids have an ester or glycosidic bond

Answer 88

hydrolysable: o simple § fats – glyceraldehyde + FA * solid * liquid -> oils (high number of unsaturated fatty acids) § waxes - glyceraldehyde + FA with 16 or more carbons o compound § phospholipids § lipoproteins § glycolipids - non-hydrolysable o steroids – derived from sterane o terpenes – consists of two or more isoprenoid units

Answer 89

usually even number of carbons - can form esters with cholesterol - saturated – only simple bonds, palmitic acid, stearic acid - unsaturated – double bonds in configuration cis, oleic acid - polyunsaturated fatty acids – have more than one double bond; linoleic acid, linolenic acid, arachidonic acid

Answer 90

they are esters of 3 fatty acids and glycerol - non-soluble in water - belong to hydrolysable lipids - in cells stored in the form of lipid droplets (not bound by a membrane) - function – storage of energy, source of carbons, heat and electrical isolation

Answer 91

basic skeleton of steroids is formed by sterane - tetracyclic hydrocarbon - most important steroid is cholesterol o important part of biological membrane o it is a precursor of all steroid hormnes and bile acids

Answer 92

nucleotide = nitrogen base + sugar (pentose) + phosphate nucleoside = nitrogen base + sugar (pentose)

Answer 93

N-glyosidic bond – in-between nitrogen base and sugar, binds to the 1st sugar carbon - Ester bond– in-between sugar ad phosphate, binds to the 5th sugar carbon - phosphodiester bond – a connection between the 3rd sugar carbon of one nucleotide and 5th sugar carbon of the second nucleotide

Answer 94

linear nucleic chains always have a free OH group at one end on 3rd carbon of pentose (3’ end) and at the other end a free phosphate bound to the 5th carbon of pentose (5’ end) - synthesis of new chain always occurs in the 5‘ -> 3‘ direction o this means that new nucleotides bind to the 3’ end

Answer 95

Proteins are biopolymers of amino acids. They are macromolecules

Answer 96

There are 21 proteinogenic AAs other AAs are formed by a posttranslational modification

Answer 97

Ala,Val, Leu, Ile, Pro, Phe, Trp, Met, they are all hydrophobic since they are non-polar

Answer 98

Gly ,Ser, Thr, Cys, Tyr, Asn, Gln They are all hydrophillic since they are polar

Answer 99

Gly ,Ser, Thr, Cys, Tyr, Asn, Gln They are all hydrophillic since they are polar

Answer 100

Gly ,Ser, Thr, Cys, Tyr, Asn, Gln They are all hydrophillic since they are polar

Answer 101

Asp and Glu. They are both negatively charged

Answer 102

Lys, Arg, His. They are all positively charged

Answer 103

ornithine citrulline, L-dihydroxyfenylalanine p (L-DOPA), β-alanine γ-aminobutyric acid (GABA), taurine

Answer 104

1) branched chain AAs (Val, Leu, Ile) 2) aromatic AAs (Phe, Trp) 3) basic AAs (Lys, Arg, His) 4) Thr, Met

Answer 105

Side chains of AAs determine final properties of proteins

Answer 106

pH value at which the net charge of a compound is zero

Answer 107

Solutions of AAs belong among ampholytes

Answer 108

contain 2 or more AAs bound by peptide bond(s) oligopeptides: 2 – 10 amino acids polypeptides: > 10 amino acids proteins: polypeptides of Mr > 10 000

Answer 109

peptide bonds

Answer 110

spacial arrangement and biological function are DEPENDENT on the amino acid composition

Answer 111

side chains of AAs influence a final structure of proteins

Answer 112

peptide bond -CO-NH- disulfide bond -S-S

Answer 113

hydrogen bonds: -H.....O- -H.....N- hydrophobic interactions: nonpolar side chains ionic interactions: -COO- /+H3N-

Answer 114

= order of amino acids * read: from N- to C- end * it is coded on a genetic level * stabilization:peptide bonds

Answer 115

a-helix or B-pleated sheets = spatial arrangement of the polypeptide chain given by rotation of the planar peptide bonds around α-carbons stabilization: hydrogen bonds between –CO- and -NH of the peptide bonds

Answer 116

α-helix (right-handed) collagen helix (left-handed, steeper)

Answer 117

= spatial arrangement of the secondary structures (folding of domains) stabilization: between side chains of AAs 1) hydrogen bonds 2) ionic (electrostatic) interactions 3) hydrophobic interactions 4) disulfide bonds

Answer 118

a function is related to the spatial structure IT DEPENDS ON AMINO ACIDS COMPOSITION

Answer 119

1) globular proteins (spheroproteins) spheroidal shape both secondary structures are abundant 2) fibrous proteins (scleroproteins) rod-like shape ,one secondary structure predominates e.g. α-keratin, collagen

Answer 120

= oligomeric structure of a protein (2 or more subunits = polypeptide chains ~ monomers) * i.e. the structure is found only in proteins composed of 2 or more chains (subunits) * stabilization: noncovalent interactions * the proteins have an „allosteric effect“ (it can generate cooperative behavior of subunits)

Answer 121

If an allosteric effector binds to one subunit, other subunits change their shape

Answer 122

1) by localization in an organism intra- / extracellular 2) by function structural / biological active 3) by shape globular / fibrous 4) by chemical composition simple / complex (conjugated) proteins

Answer 123

conjugated proteins contain polypeptide chain (= apoprotein) + nonprotein prosthetic group glycoproteins metalloproteins hemoproteins phosphoproteins nucleoproteins

Answer 124

water solubility depends on the structure * proteins form colloidal solutions (viscosity, sedimentation, light dispersion) colloidal-osmotic pressure = onkotic pressure * proteins can be salting-out of the solution (~ water sheet removing)

Answer 125

heat, whipping, shaking, radiation strong pH changes, salt of heavy metals, organic solvents, detergents

Answer 126

proteins act as antigens formation of antibodies proteins give positive reaction with biuret reagent

Answer 127

Proteins strongly absorb UV radiation

Answer 128

under physiological pH proteins are negatively charged

Answer 129

chemical reacion of peptide bonds with biuret reagent - spectrophotometry * complementary reaction with an antibody - immunochemistry * separation in an electric field - electrophoresis * denaturation

Answer 130

proteins which help correct the arrangement and formation of proteins o stop the formation of incorrect bonds or connections, some even have the capability to unfold and refold a protein o chaperons also include heat shock proteins, which allow proteins to pass though membranes

Answer 131

Protein function results from its structure. Folding of protein molecule into relevant 3D structure is determined by weak noncovalent bonds: * Electorstatic forces * Hydrogen bonds * Van der Waals forces * Hydrophobic interactions Disulfide bonds: the stabilize 3D structure of protein molecule

Answer 132

Globular proteins (insulin, actin) Fibrilar proteins (collagen, elastin)

Answer 133

They include proteins similar in their structure and function. Proteins of one protein family are coded by genes of one gene family.

Answer 134

Capability of protein molecules for self-organizing. Association into big polymers and the formation of various structures: * Filaments (actin, elastin) * Tubules (microtubules) * Sheets (membrane proteins, protein FtsZ in bacteria – tubulin homolog) * Spheres (viral capsids)

Answer 135

proteasomes

Answer 136

Ligands: ligand binding is highly selective and directly related to the function of protein. Conformational change due to binding of other molecule leads to change in activity

Answer 137

Binding of ion/atom: Ca 2+ (calmodulin), Fe 3+ (transferrin, IRP-iron regulatory protein) * Binding of small molecule: * Glycosylation (binding of saccharide): glycoprotein * Phosphorylation (binding of phosphate): protein kinase,phosphatase * Binding of GTP: GTP-binding proteins * Binding of other small molecules: heme (hemoglobin), retinal (rhodopsin) * Binding of nonprotein macromolecule: DNA (transcription factors) * Binding of protein: protein substrate (enzyme), protein antigen (antibody), cyclin dependent kinase (cyclin)

Answer 138

Protein activity can be also regulated by proteolytic cleavage: insulin, caspases

Answer 139

Negative regulation (feedback inhibition) Positive regulation

Answer 140

Two means of protein degradation: * degradation in lysosomes * degradation in proteasomes Degradation in proteasomes is based on enzymatic degradation: proteolysis, proteases

Answer 141

Ubiquitin: it labels proteins to be degraded Proteasome: protein complex for protein degradation

Answer 142

tubulin, keratin, actin, collagen

Answer 143

protein kinase C, DNA polymerase δ, pepsin

Answer 144

myosin, kinesin, dynein

Answer 145

hemoglobin, transferrin, albumin

Answer 146

ferritin, casein, ovalbumin

Answer 147

insulin, EGF, erythropoietin

Answer 148

rhodopsin, insulin receptor, EGF receptor

Answer 149

chaperones, transcription factors, cyclins

Answer 150

immunoglobulins

Answer 151

Internal support of the cell and its structures (“skeleton of the cell“) & internal organization of the cell * Movements of the cell & intracellular transport * Cell signalization

Answer 152

Protofilaments: polymer consisting of dimers of α tubulin a β tubulin Microtubule: 13 protofilaments + end (β tubulin), - end (α tubulin) of microtubules MTOC (microtubule-organizing center): ɣ tubulin Dynamic instability (+end) Polymerization (bound GTP), depolymerization (bound GDP)

Answer 153

Mitotic spindle: centrosomes (MTOC) * Flagella and cilia: structure (9 doublets +2) movement (motor protein dynein) * Tracks for the movement of organelles: motor proteins (molecular motors) dynein and kinesin

Answer 154

Colchicine (stabilization of free tubulin) * Vinblastine, vincristine (stabilization of free tubulin): employment in tumor therapy * Taxol (stabilization of microtubules): employment in tumor therapy

Answer 155

Monomers: lamins (nuclear lamina) keratins (epithelial cells and their derivates) vimentin (cells of mesenchymal origin) desmin (muscle) proteins of neurofilaments (neurons)

Answer 156

Monomeric molecules: central α-helical domain and two peripheral globular domains Fibers: polymer of tetramers (2 antiparallel dimers) Intermediate filaments: 8 twisted fibers (rope-like structure)

Answer 157

Nuclear lamina: structure (lamins) and localization function (mechanical support of nuclear envelope,disintegration and reintegration of nuclear envelope) * Intermediate filaments in cytoplasm: tissue-specific types of proteins function (mechanical resistance of the cell)

Answer 158

Monomer: actin, known as G-actin (globular)

Answer 159

Fibers: polymers of actin, known as F-actin (filamentous) Microfilaments: double-helix + end, - end of microfilaments (determined by the orientation of actin molecule) Treadmilling (+ end & - end)

Answer 160

Microvilli * Cell cortex: structure and localization function * Lamellipodia, filopodia: amoeboid locomotion of the cell * Contractile ring: cytokinesis * Contractile bundles: “muscles“ of the cell * Muscle cells: association with motor protein myosin → motility

Answer 161

Spectrin (shape of erythrocytes) Dystrophin (binding of microtubules to basal lamina)

Answer 162

Latrunculin (prevents polymerization of free actin) * Phalloidin (stabilization of microfilaments): poison from the Deathcup

Answer 163

It is an environment (net) between cells, non-cellular part of tissue It influences many cell functions, behaviors It is made up of Structural proteins (collagen, elastin), glycoproteins (fibronectin, laminin), proteoglycans (aggrecans)

Answer 164

1. Epithelia 3. Muscle tissue 2. Connective tissue 4. Nerve tissue

Answer 165

Origin in ectoderm, entoderm and mesoderm * Cells attach to each other * Minimal extracellular matrix Variable – structure, function * Protective - epidermis * Absorptive – epithelium * Secretory – glandular epithelia

Answer 166

Skin, esophagus. |t serves as a protection

Answer 167

Connects cells, tissues, organs, the most common tissue čin body * Ensures support, nutrition, protection * Origin mostly in mesoderm

Answer 168

chondrocytes * In ECM abundant proteoglycans + collagen fibers

Answer 169

Organic compound * collagen * proteoglycans * glycoproteins Anorganic compound * hydroxyapatite Ca10(PO4)6(OH)2

Answer 170

Brain and spinal cord

Answer 171

ganglia and peripheral nerves

Answer 172

Big active nucleus * Abundant rough endoplasmic reticulum * Polyribosomes * Golgi apparatus

Answer 173

involves a secretory vesicle * High productivity of molecules * Need of stimulus for exocytosis

Answer 174

No signal needed * Secretion right after synthesis * Collagen, fibronectin from fibroblasts

Answer 175

Pyramidal shape * Epithelia * Big active nucleus * Abundant rough endoplasmic reticulum * Zymogenous granules (digestive proenzymes)

Answer 176

Connective tissue * Round shape * Big active nucleus * Abundant rough endoplasmic reticulum (all over cell) * Production of antibodies

Answer 177

Round active nucleus * Smooth ER (SER) * SER and Golgi – lipoproteins * Tubular mitochondria * Lipid droplets

Answer 178

Big active nucleus * basal apparatus invaginations of cell membrane * ion channels Na+/K+ * Abundant mitochondria – ATP source (Energy for ion channels)

Answer 179

Goblet shape * Flattened nucleus in basal part of cell * Rough endoplasmic reticulum * Well developed Golgi apparatus (glycosylation) * Mucin vesicles – most of the cell

Answer 180

support, sepparates epithelium from connective tissue Filter (selective barrier), keeps cell polarity

Answer 181

basal lamina – Product of epithelia cells found also in other cells (muscle, adipose, Schwann cell) reticular lamina – Product of connective tissue cells morse sparse

Answer 182

Basal lamina: On cell membrane integrin receptors (provide contact with ECM) * To these receptors connects laminin (net) * Interconnection proteins (e.g. nidogen) enable connection of collagen IV (forms net) Reticular lamina: Collagen III (reticular fibers)

Answer 183

Derived from all 3 germ layers ectoderm * Skin and its derivatives (sweat glands) * Lining of ends of digestive tract * Lining of vagina entoderm * Lining of respiratory tract * Middle part of digestive tract and its glands * Liver, pancreas * Gallbladder lining * Thyroid and parathyorid gland, thymus mesoderm * endotel lining veins * mesotel lining body cavities

Answer 184

covering epithelium – cover outer surface or line cavities * glandular epithelium – production of liquid secretion * respiratory epithelium – exchange of gasses * sensory epithelium – reception function in taste bud or olfactory epithelium * germinal epithelium - gonads * myoepithelium – contractile cells in mammary, sweat and salivary glands

Answer 185

Characteristics of epithelium and smooth muscle cells * Smooth muscle – contain actin, myosin (contractile fibers) * Epithelium – contain keratin (intermediate filaments) - sit on basement membrane We can find it in exocrine glands (salivary, mammary, sweat) On basement membrane Contraction – helps secretion

Answer 186

Microvilli – cytoplasmatic projections * Cilia – longer, motile cell projections * Stereocilie – long, nonmotile, similar to microvilli

Answer 187

Stiffened with actin filaments

Answer 188

stiffened with mcrotubules

Answer 189

Tight junction- prevents molecules passage seals intercellular space Adherent junction- mechanical cell attachement actin filaments Desmosomes- spot junction intermediate filaments Gap junction rapid exchange of molecules Hemidesmosomes

Answer 190

1) Transmembrane protein – claudin, occludin 2) Adaptor proteins 3) Cytoskeleton - actin Closest to the apical part of cell * Closely attached plasma membranes * Prevents passage of hydrophilic molecules, ions between cells Digestive system * Blood-brain barrier * Lungs

Answer 191

1) Transmembrane protein– cadherin 2) Adaptor proteins – vinculin 3) Cytoskeleton - actin Strong connection of neighbouring cells * Resistance to tension, press * Single epithelia (e.g. endothelium)

Answer 192

1) Transmembrane protein – cadherins 2) Adaptor proteins – desmoplakin 3) Cytoskeleton – intermediate filaments Spot junction * Mechanical support of tissue exposed to pressure, tension * Skin, intestine, cardiac muscle

Answer 193

Cell-cell communcation * Various tisse types (nervous, muscle) * Pore 1.5 nm * Transmembrane proteins (connexins) make channel (connexon) * Permeable for small molecules, el. signals

Answer 194

– anchors cell to cell lamina 1) Transmembrane protein – integrin 2) Adaptor proteins – e.g. plektin 3) Cytoskeleton – Intermediate filaments (cytokeratins)

Answer 195

Dynamic structures, cell connection to extracellular matrix * Protein complex * Mediate signals transport between cell and outer environment * Important for adhesion and cell migration Integrins – in cell membrane – outside cell bind to ECM, inside cell bind to cytoskeleton (actin filaments)

Answer 196

Sheet epithelia: The most common, covering, respiratory epithelium Trabecular epithelia: Cells organized into trabecules, Liver, endocrine glands Reticular epithelium: Branched, mutually connected Special type, only in thymus

Answer 197

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale

Answer 198

The nonkeratinized epithelium has cells with nuclei in the surface layer

Answer 199

Special type of epithelia * Basal layer of cells * More layers of irregular shape * Surface – umbrella cells Umbrella cells: Big cells (1-2 nuclei) * Protection of cytotoxic urine * Thicker outer part of plasma membrane * Thickened with plaques – compose of protein: uroplakin

Answer 200

Abrasion of epithelia – renewal needed * Regenerative capacity varies in different organs * High regenerative capacity in intestine * Slow renewal in glands

Answer 201

Essential function of nucleic acids: storage and transfer of genetic information (other specific functions of RNA) Function of nucleic acids is based on their structure.

Answer 202

DNA is a polymer of nucleotides (polynucleotide chain) usually, two polynucleotide chains (strands) forming a double helix

Answer 203

Nucleotide: nitrogen-containing base + sugar pentose + phosphate Nucleoside: nitrogen-containing base + sugar pentose Nitrogen-containing bases: adenine, guanine, cytosine, thymine Pentose: deoxyribose (deoxyribonucleotide) * Phosphate

Answer 204

Purine bases: adenine (A), guanine (G) Pyrimidine bases: cytosine (C), thymine (T)

Answer 205

bond via OH group of the 3´carbon of deoxyribose of one nucleotide and phosphate of the 5´carbon of deoxyribose of the second nucleotide

Answer 206

repetated deoxyribose and phosphate

Answer 207

3´end and 5´end of polynucleotide chain Polynucleotide chains in the double helix are antiparallel Major groove and minor groove of DNA double helix B form and A form of DNA

Answer 208

Binding of polynucleotide chains is mediated by bonds between bases. Complementary pairing of bases: * A (purine) & T (pyrimidine): 2 hydrogen bonds * G (purine) & C (pyrimidine): 3 hydrogen bonds

Answer 209

RNA is a polymer of nucleotides (polynucleotide chain) usually one polynucleotide chain (strand) formation of more complex 3-D structures (double-stranded regions)

Answer 210

Nucleotide & nucleoside: similarly as in DNA * Pentose: ribose (ribonucleotide) * Bases in RNA: * Purine bases: adenine (A), guanine (G) * Pyrimidine bases: cytosine (C), uracil (U) Minor bases (tRNA) * Phosphate

Answer 211

Genophore: carrier of genetic information DNA (deoxyribonucleic acid) is the genophore of cells. RNA (ribonucleic acid) can be the genophore in some types of viruses.

Answer 212

DNA in the cell: * Chromosomes (big amount of comprised genetic information) * Plasmids (small amount of comprised genetic information)

Answer 213

Plasmids: cytoplasmic genophores they do not carry genetic information indispensable for the functioning of cell (vital genetic information is in chromosomes) Plasmids are usually found in prokaryotic cells. Prokaryotic plasmid: circular double-stranded DNA, 1.5-200x103 base pairs

Answer 214

F (fertile) plasmids: conjugation of bacteria (exchange of genetic information) * R (resistance) plasmids: resistance against antibiotics and chemotherapeutics * Col plasmids: production of proteins colicins (colicins kill other bacteria)

Answer 215

Genetic information in relevant DNA strand (similarly in RNA) is saved as a sequence of individual bases (A, G, C, T). Genetic information of the cell encodes the sequence of amino acids (primary structure) of cell proteins. The sequence of bases in DNA determines the sequence of amino acids in relevant protein.

Answer 216

a rule by which certain sequence of bases determines relevant amino acid.

Answer 217

Triplet of bases is a codon One amino acid is always determined by the sequence of 3 bases. → Genetic code is based on triplets. There are 20 common amino acids in organisms which are encoded. 4 bases (A, G, C, T) → 64 (43) combinations of triplets (codons)

Answer 218

61 triplets: they encode amino acids codon for methionine functions as the initiation codon 3 triplets: they function as stop codons

Answer 219

Genetic code is universal. * Genetic code is redundant. 61 triplets encode only 20 amino acids. 1 amino acid encoded by 1 codon (methionine, tryptophan) up to by 6 codons (leucine, serine, arginine). * 3 possibilities of reading of the sequence of triplets: reading frame

Answer 220

A gene is a segment of DNA (or RNA) which encodes a single polypeptide chain (protein) or a single RNA chain (rRNA, tRNA). Most of genes have their own stable site (gene locus) within the DNA sequence of relevant chromosome.

Answer 221

Structural genes: they encode proteins. * Genes for RNA: they encode RNA which is not a template for translation (rRNA, tRNA). * Regulatory regions of gene (promotor): they do not encode proteins as well as RNA and they are not transcribed. Specific molecules regulating gene expression bind to them.

Answer 222

Prokaryotic gene: it only contains uninterrupted DNA sequence which encodes corresponding polypeptide chain. Eukaryotic gene: it contains coding DNA sequences (exons) which are interrupted by noncoding sequences (introns). Human gene comprises approximately 3x104 base pairs.

Answer 223

Regulatory regions: they are involved in the regulation of expression. * Repetitive sequences: highly variable (DNA fingerprinting). * Mobile elements (transposons): they do not exert a stable position within DNA sequence. mechanism „cut-and-paste“ retrotransposons

Answer 224

genes which lost their function due to the accumulation of mutations.

Answer 225

Genome: complete set of DNA of the cell (organism). Genome of prokaryotic cell: chromosome + possible plasmids. Genome of eukaryotic cell: nuclear chromosomes + mitochondrial chromosomes + chloroplast chromosome (in the case of plants) + possible plasmids (only in some cases). Human genome (haploid set) comprises approximately 20 000 - 25 000 (~21 000) protein coding genes.

Answer 226

Nuclear envelope * Nuclear lamina * Chromatin * Nucleolus * other structures „Cajal bodies“ (maturation of snRNP)

Answer 227

It separates content of the nucleus (genetic information saved in DNA etc.) from rest of the cell. Nuclear envelope: inner and outer membrane nuclear pores

Answer 228

Nucleus is the place for DNA replication and DNA transcription which is separated from translation in cytoplasm.

Answer 229

Nuclear lamina: lamins (intermediate filaments) Mechanical support of nuclear envelope Desintegration and reintegration of nuclear envelope in mitosis: phosphorylation and dephosphorylation of lamins

Answer 230

Chromatin: DNA & proteins (histones + nonhistone chromosomal proteins) form linear chromosomes * Euchromatin (decondensed chromatin: active genes) * Heterochromatin (highly condensed chromatin: nanoactive genes) * constitutive heterochromatin (telomeres, centromeres) * facultative heterochromatin (X chromosome of females: Barr body)

Answer 231

Nucleolus: it contains DNA coding for rRNA Place of the production of ribosomes

Answer 232

Chromosome: DNA histones (H1, H2A, H2B, H3, H4) nonhistone chromosomal proteins Histones: basic structure of chromosome (nucleosomes) Nonhistone chromosomal proteins: three-dimensional arrangement of chromosome

Answer 233

basic structural units of eucaryotic chromosome Eukaryotic chromosome: linear, approximately 108 base pairs Prokaryotic chromosome: circular, approximately 106 -107 base pairs

Answer 234

Nucleosome: core made of histone octamer (2x H2A, 2x H2B, 2x H3,2x H4) DNA wound around the core (147 base pairs) Free DNA between nucleosomes (about 60 base pairs) There are about 200 base pairs per one nucleosome. Individual nucleosomes are joined by histone H1.

Answer 235

double helix of DNA (the diameter of fiber is 2nm) * nucleosomes with wound DNA („beads-on-a-string“) (11nm) * 30-nm chromatin fiber (30 nm) * folded loops of chromatin fiber (chromatid) (700 nm) * entire mitotic chromosome (1400 nm) interphase chromosome: own position within nucleus

Answer 236

Mitotic chromosome: 2 chromatids centromere telomeres Human chromosomes: identification of individual chromosomes

Answer 237

Chromatin remodeling complexes Histone code: specific modifications (acetylation, methylation, phosphorylation, ubiquitination) Significance of histone code: it is not fully understood

Answer 238

Chromatin is a complex of DNA and protein found in nucleus of eukaryotic cells. The function of chromatin: To package and reinforce very long DNA molecules into a more compact, denser shape and prevent the strands from becoming tangled

Answer 239

The basic repeat element of chromatin is the Nucleosome, interconnected by sections of linker DNA. Nucleosome = DNA + Histone core (Octamer of two copies of H2A, H2B, H3, H4). DNA is wrapped around the histone core. Linker DNA = DNA between two nucleosomes that is free or associated with the H1 histone This enables DNA condensation to 7 times smaller than native.

Answer 240

The secondary structure This is called the Solenoid structure It involves a string of nucleosomes coiled into a fiber (6 nucleosomes in each turn) Function of the Solenoid structure = to help package the DNA so that it is small enough to fit into the nucleus

Answer 241

The Solenoid structure is further packaged into loops (called Laemmli loops) attached to a non-histone protein scaffold (composed of Condensin I and II complex).

Answer 242

non-histone protein scaffold with loops becomes coiled into the spiral structure of chromatids

Answer 243

A chromatid is a chromosome that has been copied, the two pairs (sister chromatids) are still joined together by a single centromere.

Answer 244

Duplicated chromosomes are known as chromatids that are joined together by a centromere.

Answer 245

The position of the centromere determines the morphology of chromosomes.

Answer 246

Metacentric: centromere divides chromatids into equal length arms. 2. Submetacentric: centromere divides into chromatids into unequal length arms. 3. Acrocentric: centromere is located near the end of the chromatids so that a short arm is seen. 4. Telocentric: centromere located at one end of the chromatids

Answer 247

When the centromere malfunctions, it causes non-disjunction (ie. an error in the distribution of chromosomes during cell division)

Answer 248

Nucleolus Organiser Regions (NORs) are chromosomal regions crucial for the formation of the nucleolus. The nucleolus is located in the nucleus and it not bounded by a membrane. In humans, the NORs are located on the short arms of the acrocentric chromosomes 13, 14, 15, 21 and 22. These regions code for 5.8S, 18S, and 28S ribosomal RNA. NORs contain tandemly repetitive ribosomal RNA gene clusters which vary in length (10 -100 copies).

Answer 249

A telomere is a region of tandemly repetitive nucleotide sequences at each end of a chromosome. Telomere function: To protect the end of the chromosome from deterioration or from fusion with neighbouring chromosomes. Telomeres tend to associate with the nuclear membrane.

Answer 250

Telomeres shorten with time because they cannot replicate completely each time the cell divides; for that reason, they may be the most powerful biological clock Cells that undergo cell division continue to have their telomeres shortened. Telomere shortening is associated with aging.

Answer 251

The concept states that a normal human cell can only replicate and divide forty to sixty times before it cannot divide anymore, and will break down by programmed cell death or apoptosis.

Answer 252

Telomerase, also called Terminal Transferase, is a ribonucleoprotein that adds repeat sequences to the 3’ end of telomeres. Telomerase is a reverse transcriptase enzyme (called TERT) that carries its own RNA molecule (called TERC) which is used as a template when it elongates telomeres. Most somatic cells age as they do not make telomerase. Telomerase is abundant in stem, embryonic and cancer cells

Answer 253

The decrease in telomere length leads to senescence/lack of cell division. Telomerase activity is determined by its catalytic protein domain (called hTERT).Since hTERT expression is dependent only on the number of tumour cells within a sample, the amount of hTERT indicates the severity of a cancer. Syndromes connected with telomere shortening: Werner´s syndrome Ataxia teleangiectasia – neurons affected Dyskeratosis congenita

Answer 254

condensation (both constitutive and facultative) late replicating (both constitutive and facultative, inactive X replicates at the end of S phase) methylation (on cytosines) histones in heterochromatin are hypoacetylated (hyperacetylated histones are in active chromatin)

Answer 255

Heterochromatin is a tightly packed form of DNA or condensed DNA, which comes in a multiple of varieties. There are two types of heterochromatin (HC) - Constitutive Heterochromatin and Facultative Heterochromatin, which differ depending on the DNA that they contain. Constitutive heterochromatin is polymorphic in size – without phenotypic effect Constitutive heterochromatin is located at the centromeres of all chromosomes.

Answer 256

Heterochromatin: More condensed Silenced genes (methylated) Gene poor (high AT content) Stains darker with banding techniques Euchromatin: Less condensed Gene expressing Gene rich (high GC content) Stains lighter with banding techniques

Answer 257

ICF syndrome= Immunodeficiency, Centromere instability, Facial abnormalities Inherited in an autosomal recessive manner. ICF syndrome is associated with mutations in the gene encoding DNA methyltransferase 3b (DNMT3b) instability of the constitutive heterochromatin on chromosomes 1q, 16q. Rett syndrome – low levels of norepinephrine in the brain. This could be regarded as a neurodevelopmental condition as opposed to a neurodegenerative condition. Usually arises from new mutation within the gene MECP2 (encoding methyl cytosine binding protein) located on the X chromosome.

Answer 258

A histone modification is a post-translational modification (PTM) to histone proteins which includes methylation, phosphorylation, acetylation, ubiquitylation or sumoylation. PTMs impact gene expression by altering chromatin structure.

Answer 259

Acetylation of histones, represents a type of epigenetic marker within chromatin. Acetylation removes the positive charge on the histones, thereby decreasing the interaction of the N termini of histones with the negatively charged phosphate groups of DNA. As a consequence, the condensed chromatin is transformed into a more relaxed structure that is associated with greater levels of gene transcription. The modifying enzymes involved in histone acetylation are called histone acetyltransferases (HATs) and they play a critical role in controlling histone H3 and H4 acetylation. Deacetylation of histones, restores the positive charge on histones which increases their attraction to DNA. This leads to formation of a condensed chromatin structure with inactive gene transcription due to inaccessibility for transcription factors. Histone deacetylaces (HDACs) catalyze the hydrolytic removal of acetyl groups from histone lysine residues.

Answer 260

The normal human karyotypes contain 22 pairs of autosomal chromosomes and one pair of sex chromosomes (allosomes). The normal karyotype for females contain two X chromosomes and are denoted 46,XX The normal karyotype for males contains both an X and a Y chromosome and is denoted 46,XY

Answer 261

X chromosome inactivation (also called Lyonization - but this is outdated) is a process by which one of the copies of the X chromosome is inactivated in female mammals. The choice of which X chromosome will be inactivated is random in placental mammals (eg. Human), but once an X chromosome is inactivated it will remain inactive throughout the lifetime of the cell and its descendants in the organism. Females are made of a mosaic of cells with inactive paternal and maternally derived X chromosomes.

Answer 262

Initiation of X chromosome inactivation (XCI) is genetically controlled by a master regulatory locus named the X-inactivation center (Xic). Xic harbors a gene encoding a long non-coding RNA (lncRNA) called Xist.

Answer 263

Recruitment of gene repressive complexes (eg. PRC2) Modification of histones. Deposition of DNA methylation on CpG islands.

Answer 264

The segregation of alleles in meiosis and their combination in gametes. Recombination as a consequence of cross-over between homologous chromosomes in meiosis. Sexual reproduction (random mating). Diffuse centromeres. Mutations in genes or chromosomes

Answer 265

The cell cycle is a four-stage process in which the cell - 1) Increases in size (Gap 1 or G1 stage) 2) Copies its DNA (Synthesis or S stage) 3) Prepares to divide (Gap 2 or G2 stage) 4) Divides (Mitosis or M stage) The stages G1, S and G2 make up interphase, which accounts for the span between cell divisions.

Answer 266

DNA damage (in G1) Incomplete replication (in G2) Non-attachment to the spindle (between metaphase and anaphase) In meiosis – for incomplete synapsis and recombination (in pachytene)

Answer 267

Rb = The retinoblastoma protein is a tumor suppressor protein that is dysfunctional in several major cancers. One function of Rb is to prevent excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide. E2F = A transcription factor Rb binds to the E2F1 transcription factor, preventing it from interacting with the cell's transcriptional machinery. When Rb is inactivated, E2F1 facilitates G1/S transition and S-phase.

Answer 268

the division of somatic cells that give rise to genetically identical cells in which the number of chromosomes is maintained. From one diploid maternal cell → two diploid daughter cells. Division involves the separation of sister chromatids.

Answer 269

The centrosome: This serves as the major Microtubule Organizing Center (MTOC) in animal cells. The Microtubule Organizing Center (MTOC) is a structure from which microtubules emerge. The MTOC is not present in fungi or plant cells. The centrosome is duplicated in S phase. Duplicated centrosomes separate and go to opposite poles (using kinesin related motor protein Eg5). Separated centrosomes reorganise microtubules to mitotic spindles.

Answer 270

Centrosomes are surrounded by a mass of protein - the Pericentriolar Material (PCM). The PCM contains proteins including 1) g-tubulin, 2) Pericentrin (initial establishment of organized microtubule arrays) and 3) Ninein (transport of proteins) etc. These proteins are responsible for microtubule nucleation (the event that initiates the new formation of microtubules) and anchoring. Cells use various proteins to aid microtubule nucleation.

Answer 271

A kinetochore is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. Kinetochore functions include 1) Anchoring of chromosomes to MTs in the spindle; 2)Verification of anchoring; 3)Activation of the spindle checkpoint and 4) Participation in the generation of force to propel chromosome movement during cell division.

Answer 272

Motor proteins: dynein, dynactin – responsible for chromosome movement Spindle checkpoint proteins: Regulatory proteins: kinases, phosphatases etc!.

Answer 273

responsible for the transition from metaphase to anaphase. It ensures that the cell cannot proceed to anaphase until all chromosomes have been attached to microtubules emanating from both poles.

Answer 274

Genes: MAD, BUB, CDC (Cell division cycle) These genes encode proteins localized to unattached kinetochores to ensure and monitor the attachment of the kinetochore to the spindle. APC encodes the Anaphase Promoting Factor This gene encodes a protein involved in the destruction of mitotic proteins involved in sister chromatid segregation. Topoisomerase II (TOPO II = scaffold protein I) produces transient double strand breaks in DNA. It plays a role in chromosome condensation and releases tension during untangling of daughter DNA molecules after replication.

Answer 275

At metaphase-to-anaphase transition, cohesins are cleaved by separin and leave the DNA, thereby allowing the chromatids to segregate to opposite poles. The inhibitor of separin, securin, is degraded only when all kinetochores have formed stable bipolar spindle attachment. APC ( anaphase promoting complex) targets securin for destruction, separase is released and cleaves subunits of cohesin, thus separating the sister chromatids.

Answer 276

Meiosis is a type of cell division that results in four daughter cells, each with half the number of chromosomes as the parent cell. This process is vital for the production of gametes and plant spores.

Answer 277

Prophase is the starting stage of cell division in eukaryotes. It is recognized by the condensing and separation of chromosomes . Meiosis involves two rounds of chromosome segregation and therefore undergoes prophase twice, resulting in prophase I and prophase II.

Answer 278

Prophase I is the most complex phase in all of meiosis because homologous chromosomes must pair and exchange genetic information. Prophase II is very similar to mitotic prophase.

Answer 279

Prophase I is divided into five phases: Leptotene Zygotene Pachytene Diplotene Diakinesis

Answer 280

A bivalent, sometimes referred to as a Tetrad, is the association of a pair ofhomologous chromosomes physically held together by at least one DNA crossover. This physical attachment allows for the alignment and segregation of the homologous chromosomes in the first meiotic division.

Answer 281

Metaphase – bivalents are in the equatorial plane of the cell without the splitting of centromeres. Anaphase - migration of homologous chromosomes to opposite poles. This is done randomly but takes into account parental origin. Telophase – A nuclear envelope reforms around each chromosome set, the spindle disappears and cytokinesis (ie. the division of the cytoplasm) follows. Many cells that undergo rapid meiosis do not decondense the chromosomes at the end of telophase I. The daughter nuclei are formed.

Answer 282

Segregation of chromosomes is random but one member of the pair comes from the mother and one from the father.

Answer 283

This is the development and production of the male and female germ cells required for the formation of a new individual. Gametogenesis begins with the migration of primordial germ cells to the gonads during early fetal development. They multiply by mitosis, and, once they have reached the gonadal ridge in the late embryonic stage, they are referred to as gametogonia. From gametogonia, male and female gametes develop differently – males by spermatogenesis and females by oogenesis.

Answer 284

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. It begins at puberty and is a continuous process in men.

Answer 285

Oogenesis differentiation of the ovum (egg cell) into a cell competent to further develop when fertilized. It is developed from the primary oocyte by maturation. The process begins in early embryonic life.

Answer 286

The failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Answer 287

Reduction of diploid chromosomal number to haploid Segregation of alleles in M I, M II (Mendel´s law) (alleles segregate with homologous chromosomes) 3. Random assortment of homologues → random combination maternal and paternal chromosomes in gametes (Mendel´s law) = genetic variability 4. Increase of genetic variability by crossing-over (chromatids with segments of maternal and paternal origin)

Answer 288

Nondisjunction in M I = failure of homologs to disjoin Nondisjunction in M II = failure of chromatids to disjoin Consequences for 1 chomosomal pair: disomic + nullisomic gametes After fertilization: trisomic or monosomic zygote Consequence for the whole chromosomal set: diploid gamete After fertilization: triploid zygote Anaphase lag of 1 chromosome consequence: nullisomic gamete After fertilization: monosomic zygote

Answer 289

Nondisjunction or anaphase lag (postzygotic) → mosaic of two (or more) cell lines with different karyotype Endoreduplication – division of chromosomes - not followed by division of cell (failure of cytokinesis) - tetraploidy

Answer 290

division of chromosomes without division of cell

Answer 291

Unequal crossing-over → interstitial duplication and deletions Crossing-over involving structurally abnormal chromosome (with balanced aberration) and normal homologue → unbalanced structural abnormality

Answer 292

Abnormal - transverse splitting - izochromosome of one arm (=duplication of one arm and loss of second arm)

Answer 293

Dispermy = fertilization of ovum by two sperms → triploidy (69,XXX or XXY) - partial mole (abnormal pregnancy = abundant trophoblast, poor embryonic development – in case of additional paternal chromosomal set !!) Fertilization of ovum and polar body, each of them by sperm with different gonosome → chimaera (46,XX/46,XY)

Answer 294

Gynogenesis - ovarian teratoma (benign tumor) = division of ovum without fertilization (duplication of chromosomes, karyotype 46,XX)

Answer 295

Androgenesis - hydatiform mole - complete (= pathological pregnancy = hypertrophy of trophoblast, fetal tissues are not present) origin: dispermy or duplication of sperm chromosomes in ovum with completely destroyed female nucleus x Partial mole = triploid product with additional set of paternal chromosomes (hypertrophy of trophoblast + reduced embryonal tissues)

Answer 296

Origin of complete mole - only paternal chromosomes -absence of maternal contribution

Answer 297

Dominance - A trait that manifests in both AA and Aa genotypes - The dominant allele masks the expression of the recessive allele in heterozygotes. Recessive – - A trait that only manifests in the aa genotype.

Answer 298

HOMOZYGOTE – two identical alleles at a given locus on a pair of homologous chromosomes - 1 type of gametes HETEROZYGOTE – two different alleles at a given locus on a pair of homologous chromosomes - 2 different gametes

Answer 299

n – number of followed genes number of gametes 2n number of zygotes 4n genotype ratio: ( 1 : 2 : 1 )n phenotype ratio: ( 3 : 1 )n

Answer 300

Uniformity of phenotype in the F1 generation This feature was identified with reciprocal crosses - the purpose of which was to observe the effect of parental mating on the inheritance of a trait, i.e., if a trait is sex-linked or not. During the formation of gametes: 2. Principle of segregation Two alleles of one gene separate from each other into two gametes. 3. Principle of combination - Independent assortment Alleles of two or more allelic pairs (genes) assort independently of one another. There are many types of gametes possible as there are random combinations of paternal and maternal chromosomes

Answer 301

Genes on chromosome are in a linear order. The number of linkage groups is equal to the number of homologous chromosomes pairs. Gametes with an assortment of linked alleles, differing from a parental one, form only in the case of recombination (crossing over). Frequency of recombination is associated with the strength of linkage.

Answer 302

Mendel´s 3rd law only applies to allelic pairs (genes) carried on different pairs of homologous chromosomes (independent assortment) Genes on 1 chromosome – are not assorted independently - are linked, transmitted together into gametes Genes on 1 chromosome = linkage group Strength of linkage depends on their distance: the further apart genes are from each other – the higher the probability of crossing over.

Answer 303

The ABO blood type of each person is determined by a single gene. For the A type, there is a gene for GTA, a glycosyltransferase that adds N-acetylgalactosamine. For type B, the gene encodes GTB, a different glycosyltransferase that adds galactose. For type O, neither enzyme is made.

Answer 304

the genes of interest are located on one chromosome and their alleles have a tendency to be inherited together o Two genes carried by one homologous chromosome segregate together, if there is no crossing over o It is the result of the fact that we have several more genes than chromosomes

Answer 305

– a group of genes (loci), which are linked and thus preferably inherited together o humans have 2 haplotypes of a gene – one on each chromosome o example - Y chromosome or MHC complex on 6p21.3 (codominant gene in complete linkage) § men are hemizygotes for characteristics coded on non-homologous regions of Y chromosomes § Y-haplotype is identical from father to son, which is used in genealogic studies and we can examine the inheritance of Y chromosome through centuries

Answer 306

First law: genes are arranged in linear order on chromosomes - Second law: genes of one chromosome form a linkage group. The number of linkage groups of the organism is identical to the number of pairs of its homologous chromosomes - Third law: Crossing over (gene exchange) can occur between genes of homologously paired chromosomes. Frequency of crossing over is directly proportional to the distance of genes on the genetic map (the larger the distance, the higher the change of crossing over)

Answer 307

There are always more genes than chromosomes in an organism, therefore not all genes undergo independent assortment - During complex linkage, genes are so close to each other that they do not segregate during crossing over - In gametes, there are only combinations of alleles which are also present in parents – due to complete linkage there is no crossing over

Answer 308

Dihybrid cross with incomplete linkage - Individual genes are on the same chromosomes but so far apart that they can separate through recombination (crossing-over), the further apart, the higher the chance of separation, but the maximal probability of recombination is 50% - Frequency of crossing-over is directly proportional to the distance between genes

Answer 309

From the number of recombined and non-recombined offspring in an analytical backcross– B1 - With the help of Morgan or Bateson’s number o Morgan’s number: p = recombinant / whole population § p = 0 = complete linkage p = 0,5 = free assortment (cannot be more than 0,5 o Bateson’s number: c = non-recombinant / recombinant § measure how many time more probable is the formation of non-recombinant gametes than recombinant § lays between 1 (independent assortment) and infinite (complete linkage) - there are more non-recombined gametes than recombined

Answer 310

Differences in the DNA sequences between individuals (ie. DNA variability) arise from mutations and polymorphisms. A mutation is a permanent heritable change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke. Such changes in the genome are frequent. However, most mutations are functionally insignificant. Some have a minor effect on the phenotype, some are deleterious (eg. they cause a genetic disorder or fetal miscarriage)

Answer 311

A genetic polymorphism is defined as the inheritance of a trait controlled by a single genetic locus with two alleles, in which the least common allele has a frequency of about >1%. It is a difference in DNA sequence among individuals, groups, or populations. Alleles with a frequency of < 1% are considered rare genetic variants. Most polymorphisms are without effect on human health, but some can modify the risk associated with common diseases in a population (eg. increase an individuals risk for tumor or neural tube defect).

Answer 312

Allelic heterogeneity is the phenomenon in which different mutations at the same gene locus lead to the same or very similar phenotypes.

Answer 313

Single nucleotide polymorphisms Microsatellites Minisatellites Classical satellites Copy number variants (CNVs) Indel variants

Answer 314

A single-nucleotide polymorphism (SNP, pronounced snip) is a DNA sequence variation occurring when a single nucleotide (adenine (A), thymine (T), cytosine (C), or guanine (G]) in the genome differs between members of a species or paired chromosomes in an individual. SNPs occur in the coding and noncoding regions of human genome. SNPs within a coding sequence will not necessarily change the amino acid sequence of the protein that is produced, due to the degeneracy of the genetic code. If they do cause a change in the amino acid sequence this can be very problematic (eg. metabolic enzymes can be altered etc.).

Answer 315

Short tandem repeats (STRs) occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other. Microsatellites are STRs

Answer 316

A minisatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from 10 – 60 base pairs) are typically repeated 5-50 times. The length of minisatellites can be variable between individuals. They occur in telomeres and subtelomeric regions of the genome.

Answer 317

Classical satellites are repeated units of hundreds or thousands of nucleotides. They are the main component of functional centromeres and form the main structural constituent of heterochromatin. The variability in these regions is generally without a phenotypic effect.

Answer 318

Copy number variation (CNV) is a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals in the human population. Copy number variation is a type of structural variation.

Answer 319

Indel is a molecular biology term for an insertion or deletion of bases in the genome of an organism. Indel variants are classified among small genetic variations, measuring from 1 to 10 000 base pairs in length.

Answer 320

These can act as frameshift mutations. They can alter the translational reading frame of the gene. It can lead to the formation of a new stop codon and the production of a protein with loss of function. DNA exposure to acridine dyes can induce insertions or deletions

Answer 321

Mutations in promotor regions can affect gene expression. They can lead to the following: Impaired binding of transcription factors. Decreased affinity of RNA polymerase and reduced transcription. Mutations in the boundary between exons and introns can interfere with the process of splicing.

Answer 322

This arises due to autosomal (chromosome 15) recessive mutations in the hexosaminidase A gene which cause the intron between exon 12 and 13 to not be removed. This causes a defect in the beta-hexosaminidase A enzyme and the accumulation of the GM2 ganglioside within nerve cells in the brain and spinal cord leading to toxicity. RNA splicing mutations can occur at the boundary between the exon and the intron in the pre-mRNA.

Answer 323

Interspersed repetitive sequences are identical or nearly identical DNA sequences that are scattered throughout the genome, as a result of transposition or retro-transposition events. They differ from tandem repeat DNA in that rather than the repeat sequences coming right after one another, they are dispersed throughout the genome and nonadjacent.

Answer 324

Class I: Retrotransposons – replication through RNA intermediate by reverse transcription. A new copy of a DNA sequence is then inserted into another place in the genome. Class II: DNA transposons – ´jumping genes´ are DNA sequences that move from one location in the genome to another (using the enzyme DNA transposase).

Answer 325

LINEs are a family of transposons, where each LINE is about 7000 base pairs long. LINEs are transcribed into mRNA and translated into protein that acts as a reverse transcriptase or an integrase. The reverse transcriptase makes a DNA copy of the LINE RNA that can be integrated (using integrase) into the genome at a new site. The only abundant LINE in humans is LINE-1.

Answer 326

Non-coding transposable elements (TEs) that are about 100 to 700 base pairs in length. They are transcribed into tRNA or rRNA by RNA polymerase III. They do not encode functional reverse transcriptase and rely on LINE partners for transposition.

Answer 327

Long terminal repeats (LTRs) are identical sequences of DNA that repeat hundreds or thousands of times found at either end of retrotransposons or proviral DNA formed by reverse transcription of retroviral RNA. They are used by viruses to insert their genetic material into the host genomes.

Answer 328

Types of mutations: Spontaneous mutations are the result of endogenous errors in natural biological processes. They arise from a variety of sources, including errors in DNA replication, spontaneous lesions, transposable genetic elements and reactive oxygen species. Induced mutations are the result of agents in the environment that cause changes in DNA structure. Examples would include the use of ionizing radiation (eg. X-rays, gamma rays), chemical and biological mutagens for inducing variation.

Answer 329

Chemical mutagens (Direct mutagens) include: Alkylating agents Nucleotide base analogs (structural similarity eg. bromouridine - an analogue of thymidine) Acridine dyes – insertions → frameshift mutations Nitric acid – base deamination → error in base pairing Others: e.g. polycyclic aromatic hydrocarbons Indirect mutagens – reactive oxygen products arise after metabolic activation (eg. cytochrome dependent oxygenase whose oxidized intermediates are reactive and affect DNA). Biological mutagens include viruses – ie. the viral nucleic acid integrates into the genome of the host cell.

Answer 330

A point mutation affects one single nucleotide base pair.

Answer 331

A gene mutation - results from a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is commonly found.

Answer 332

A genomic mutation - results in a change to chromosome number: Euploidy is a condition when a cell or an organism has one or more than one complete set of chromosomes. When a human cell has an extra set of 23 chromosomes, it is called euploid. Monoploidy is a condition when a cell has lost an entire set of chromosomes. c) Aneuploidy is a condition when a cell has one or more chromosomes (not an entire set) missing or present in excess.

Answer 333

A chromosomal mutation - results from a structural aberration in a chromosome. It is the consequence of double strand DNA breaks and the loss/gain of a chromosomal segment or abnormal rearrangement of a chromosomal segment (which can be detected under a light microscope).

Answer 334

A synonymous mutation is the evolutionary substitution of one nucleotide base for another in an exon of a gene coding for a protein, such that the produced amino acid sequence is not changed.

Answer 335

Nonsynonymous or Missense mutation is a point mutation/substitution in which a single nucleotide change results in a codon that codes for a different amino acid. (SICKLE CELL DISEASE)

Answer 336

A nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon and a truncated usually non-functional protein product. (NEUROFIBROMATIS TYPE 1)

Answer 337

An elongation mutation is a point mutation that changes a stop codon into an amino acid coding triplet.

Answer 338

Frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three. (AB0 BLOOD GROUPS AND TAY SACHS DISEASE)

Answer 339

Deletions: 3 or a multiple of 3 bases e.g. cystic fibrosis the most frequent mutation = 3 base-pair deletion → 1 amino acid is missing (delta F 508 = phenylalanine is missing) indel variant Total gene deletion e.g. X- linked ichtyosis There is a complete deletion of the steroid sulphatase gene Large deletions within a gene e.g. Duchenne muscular dystrophy There is a large deletion within the dystrophin gene. Whole gene duplication e.g. Charcot –Marie-Tooth

Answer 340

Unequal crossing over (aberrant recombination) Unequal exchange between misaligned sister chromatids Insertion of mobile elements (transposons LINE, Alu) –larger insertions

Answer 341

The risk of chromosomal abnormalities (trisomies) are strongly associated with increased maternal age eg. Down Syndrome. This is linked to an increased risk of nondisjunction in aging women.

Answer 342

Mutations can lead to loss of enzyme function. These mostly become expressed by recessive inheritance Mutations can cause a gain in abnormal function or to the production of an abnormal structural protein. They mostly become expressed by dominant inheritance Dominant-negative mutations (also called antimorphic mutations) cause an abnormal altered gene product which inhibits the protein produced by the normal allele in a heterozygote.

Answer 343

Cancers - sporadic = non-heritable, multifactorial predisposition - heritable - 5% of tumors familial (AD heredity with reduced penetrance) Cancers are genetic disorders - consequences of mutations and other genetic changes and alteration of epigenetic mechanisms (epigenetic mechanisms comprise changes in gene expression without any modification of the DNA sequences, e.g. DNA methylation, histone modification…) Cancer = malignant tumor Tumor = abnormal mass of tissue – benign (not cancer) or malignant (cancer)

Answer 344

Forms: sarcomas – mesenchymal tissue carcinomas – epithelial tissue hematopoetic and lymphoid malignancies (leukemias, lymphomas)

Answer 345

uncontrolled growth, invasivity, metastases Cancer cells are resistant to signals normally leading to growth inhibition, to apoptosis, to inhibition of angiogenesis and ability to produce metastases

Answer 346

= multistep process – genetic and environmental factors multiple mutations (in growth controlling genes) multiple causes and mechanisms

Answer 347

Sporadic cancers = consequences of mutations of specific genes (growth-controlling genes) in somatic cells: 1. Proto-oncogenes (AD)→ oncogenes → abnormal cell division 2. Tumor suppressor genes (AR) - loss of both alleles → abnormal cell division 3. Mutator genes = genes involved in reparation (AR)→ increased frequency of mutations and chromosomal changes = genome instability = high risk of tumors (in recessive homozygotes) = indirect effect of mutator genes on malignant transformation

Answer 348

- chemical carcinogens (induction of DNA adducts, breaks of chromosomes, deletions, fusions …) - physical: UV, ionizing radiation - biological: DNA tumor viruses (e.g. Human papilloma virus, EBV – B-cell lymphoma) RNA tumor viruses – retroviruses (e.g. HTLV – T-cell leukemia)

Answer 349

Non-genotoxic carcinogens: induction of inflammation, support of proliferation, changes in epigenetic mechanisms (DNA methylation, histone modification, i.e. change in gene expression)

Answer 350

Oncogene = abnormal form of a gene involved in normal cell growth, i.e. proto-oncogene Proto-oncogenes: promote cell survival, proliferation, differentiation Role of proto-oncogenes products: - in cell communications - in transport of signal from cell surface to the genes which regulate cell cycle

Answer 351

growth factors (e.g. proto-oncogene SIS codes for a part of growth factor PDGF) growth factor receptors (e.g. HER2/NEU=ERBB2 codes for receptor of EGFR) GTP binding proteins, GTPases ( e.g. proteins of RAS gene family) tyrosinkinases (e.g. abl, src) cytoplasmatic proteins (e.g. proteinkinases) transcription factors (e.g. fos, jun, erb) cell cycle regulation proteins (e.g. myc, myb) anti-apoptotic proteins

Answer 352

= gain of function changes Mechanisms: gene mutation chromosomal rearrangement: translocation, inversion retroviral insertion amplification epigenetic changes – e.g.changes in gene methylation, histone modification (resulting in an abnormal gene expression)

Answer 353

synthesis of an abnormal product as a consequence of a change in gene structure (via mutation or fused gene) = qualitative change increased synthesis of normal product as consequence of a change in regulation of transcription (position effect), or amplification = quantitative change Only change of one allele can lead to abnormal cell division (i.e. AD = dominant character of mutation of proto-oncogene)

Answer 354

CML = chronic myelogenous leukemia Ph1 chromosome = t(9q;22q) = reciprocal translocation of proto-oncogene c-ABL from 9q to 22q near to proto-oncogene BCR → fused gene BCR/ABL → abnormal protein with stable tyrosine kinase activity = abnormal stimulation of cell division BL = Burkitt lymphoma – t (8q;14q) Proto-oncogene c-MYC is transferred from 8q to 14q near to immunoglobulin genes (IgH) → abnormal transcriptional activity of proto-oncogene in new position → increased synthesis of normal product

Answer 355

„double minutes“ – free circular copies of amplified oncogene (non-mutated) HSR=homogenously staining regions = amplified copies tandemly inserted to chromosome

Answer 356

DNA tumor viruses - they introduce oncogenes to the cell Oncogene = viral gene encoding protein essential for viral replication After integration of virus: product of viral oncogene interfere with normal cell processes, such as function of tumor suppressor genes … e.g. HPV – human papilloma virus (vaginal carcinoma)

Answer 357

Acute tumor RNA viruses – insert oncogenes - homologous to cell proto-oncogenes (i.e. mRNA copies of cell proto-oncogenes) = process called transduction

Answer 358

Latent tumor viruses (slowly transforming) - lack of oncogene integration of virus to specific sites in genome near the cell proto-oncogene = insertion mutagenesis After viral integration: strong regulation viral sequences – (LTR sequences) increase expression of cell proto-oncogene e.g. ALV = avian leukosis viruses

Answer 359

= RNA tumor viruses – rapidly transforming Their oncogenes – homologous to cell proto-oncogenes viral oncogenes (without introns) Origin = from cell proto-oncogenes Probable origin: Integration of virus (DNA copy of viral genome transcribed by reverse transcriptase) to host genome near cell proto-oncogene replication and transcription of viral genome with genome of host cell mRNA transcript of cell proto-oncogene after introns splicing is „picked up“ by virus together with viral genome and after subsequent mutations in transduced gene, virus can be transferred to another cell (together with intact viral particles)

Answer 360

induction of immunosuppression

Answer 361

Products - suppress cell division and abnormal proliferation, promote apoptosis Codes for kinase inhibitors, check-point control proteins, proteins that promote apoptosis… loss of function of both alleles → malignant transformation = recessive character of mutation Loss of function of tumor suppressor genes via: point mutation deletion chromosome loss abnormal methylation (epigenetic change) mitotic recombination

Answer 362

Retinoblastoma (RB) – two-step origin of cancer Hereditary tumor: bilateral 1st step = germline mutation (or deletion) of one allele of Rb1 gene = heritable or „de novo“ origin in one germ cell of parent mutation in all cells of body = individual is heterozygote 2nd step: somatic mutation, or other genetic change of the 2nd allele in one cell of retina = loss of heterozygosity (LOH) b) Sporadic form : unilateral mutation of both alleles are somatic - in one cell of retina Tumor suppressor gene RB1 located on chromosome No 13

Answer 363

Retinoblastoma: recessive character of mutation of tumor suppressor gene RB1 on the cell level Heredity of retinoblastoma: AD with reduced penetrance

Answer 364

Wilms tumor: embryonal tumor of kidney - nephroblastoma Li-Fraumeni syndrome = heritable mutation of TP53 = tumor families = different tumors in young people in family Tumor suppressor gene TP53 – protein p53=transcription factor Function: manager of genes involved in DNA reparation and apoptosis blocks cell cycle and starts DNA reparation in G1 or G2 (cell cycle checkpoints) if DNA damage is unrepaired it starts apoptosis Mutation of TP53 in many tumors

Answer 365

Causes of heritable tumors: Heredity of germinal mutations (or deletions) of one allele of tumor suppressor genes (e.g. retinoblastoma, nephroblastoma, Li-Fraumeni syndrome…)

Answer 366

Evidence for tumor heredity: same cancer or same cancer type in more members of family early onset of tumor bilaterality of multifocality of tumor more than one type of cancer in a single person (breast and ovarian cancer) cancer occuring in the sex not usually affected (breast cancer in man)

Answer 367

Genes responsible for DNA repair – Recessive homozygotes are not able to repair DNA damage→high sensitivity to mutagens, high risk of tumors Mutations have recessive character Example: heritable nonpolyposis colon cancer chromosome instability syndromes = chromosomal breakage syndromes

Answer 368

- Gender is determined by sperm

Answer 369

- sex-limited – expressed only in one sex – secondary sexual characteristics o genetically based in both sexes, but it’s only expressed in one (e.g. gene for the development of shell is also present in cocks but it is not expressed in them) - sex-influenced – level of expression is different in different sex (e.g. early baldness as an AD trait in men) - both are encoded on autosomes

Answer 370

no disease carried on Y – it is too small o in X it depends on the site, either homologous or heterozygous site o homologous site – traits incompletely linked to sex o heterologous site – traits completely linked to sex

Answer 371

contains pseudoautosomal site o specific site on chromosomes X a Y -for genes in homologous site applies autosomal type of heredity - one of the largest chromosomes contains 1098 genes = is indispensable - so that there is a balanced genetic dose in men and women-> Barr body

Answer 372

pseudoautosomal homologous region – on distal ends of short (Xp a Yp) and long (Xq a Yq) arms of sex chromosomes are homologous regions, in these regions recombination can occur o ensure the pairing with chromosomes X - SRY gene on Yp determines male gender (SRY gene is found in the SRY region = Sex-determining region Y) o SRY gene helps in the formation of testes → production of testosterone

Answer 373

XX or XY (if there is translocation/deletion of SRY region) - embryo – formed primarily as a woman - until 5. week of pregnancy nothing happens - „quite before the storm “ - primitive sex cords break down -> proliferation of epithelial cortical cords - oestrogen – from the mother, placenta + fetal ovaries o development of paramesonephric Müllerian ducts -> development of uterus and uterine tubes o development of mesonephric Wolffian ducts -> differentiation of male genitalia

Answer 374

Leydig cells in mesenchyme -> production of androgen (testosterone) o Formation of vas deferens and epididymis - 7. week pregnancy – formation of zinc finger proteins -> proliferation of testicular cords -> differentiation of external genitalia - 7. month - regression of testes into the scrotum

Answer 375

male phenotype with genotype 46, XX can have 2 causes o 1) abnormal crossing over - gene SRY translocated to X § X with SRY region – genotype of a woman, phenotype of a male -> sterile § In the same way, it can also receive Y with no SRY region – genotype of a male XY, phenotype of woman, no menstruation o 2) translocation – SRY gene translocated into autosome - female phenotype with genotype 46, XY can be caused by deletion or mutation of SRY genu

Answer 376

a) hermaphroditism – presence of both ovarian and testicular tissue; double-faced genitalia (ambiguous), usually sterile b) pseudohermaphroditism – presence of gonadal tissue of only one sex but with ambiguous or opposite external genitalia; secondary sexual characteristics of opposite sex o female pseudohermaphroditism 46, XX; normal ovaries, but external male genitals and secondary sexual characteristics § congenital adrenal hyperplasia - AR disorder, deficiency of 21-hydroxylázy of adrenal cortex, cortisol and aldosterone down, androgens up o male pseudohermaphroditism 46, XY; normal testes, but outer female genitalia and secondary sexual characteristics § 1) deficiency of steroid 5-α-reductase - AR disorder, androgens down § 2) androgen insensitivity syndrome - X linked disease, mutations of androgen receptors - androgens – hormones responsible for the development of male sex organs and development of secondary sexual traits (testosterone is an androgen) z

Answer 377

Monogenic disorders with classic Mendelian inheritance are o dominant in structural defects o recessive in enzyme defects – enzymes are produced in excess, one allele is therefore enough to maintain a normal working metabolism

Answer 378

one parent is affected (heterozygote) = 50% children are effected heterozygotes and 50% children will be healthy o both parents are affected (heterozygotes) = 25% children will be affected homozygotes, 50% children will be affected heterozygotes and remaining 25% of children will be healthy o effected are usually heterozygotes, because homozygotes have a more severe progression of disease and die at an early age o vertical pedigree character – in each generation there is an effected member § technically does not always have to apply due to incomplete penetrance (individual is not sick, even though it has the genes for the disease) § inheritance of disease is not gender dependent o healthy individuals have usually heathy children (if there isn’t a mutation de novo)

Answer 379

manifestation of disease only in recessive homozygotes o if both parents are carriers then they will have 25 % children effected, 25 % healthy and 50 % carriers o horizontal pedigree character – healthy individual has a sudden sick child o AR disorders are the most common in consanguinity

Answer 380

Mutated genes are linked to gonosomes => gender of child and parents must be put into account o men have only one X chromosome (are hemizygotes), are either healthy or sick o women have two X chromosomes and can be sick, healthy or carriers (1 mutated and 1 healthy X) o sick man -> 100% healthy children, but all daughters are carriers o mother carrier -> 50% sick sons, 50% carrier daughters o disease occurs every second generation (women carriers transfers the disease to their son, who is then sick, transfers it to his daughter, she is a carrier but appears healthy à disease skipped a generation § this type of heredity looks like incomplete penetrance o if one woman is sick (and suspects that the mutation did not form de novo) § father had to be sick and mother carrier § all sons will be sick and all daughter will be carriers § exception in * women with Turner syndrome (X0) – only one X -> will always be sick if it receives a mutated allele (technically a hemizygote) * women with testicular feminization syndrome (XY) – externally a woman, but has testes (also hemizygote) o pedigree § disease can never be carried from father to son, men are sick only through the female line § daughters of sick men are always carriers

Answer 381

are rare o effected man + healthy woman -> healthy sons, sick daughters

Answer 382

- lactose Intolerance - - Adult polycystic kidney disease – - Neurofibromatosis type 1 (NF1, von Recklinghausen disease) - Tuberous sclerosis - Huntington disease - Hereditary spherocytosis - Osteogenesis imperfecta - Ehlers-Danlos syndrome - Marfan syndrome - Achondroplasia - Familiar adenomatous polyposis coli (FAPC) - Retinoblastoma

Answer 383

-Primary hemochromatosis („bronze diabetes “) - Cystic fibrosis - α1-antitrypsin deficiency - Congenital adrenal hyperplasia (CAH) - Phenylketonuria - Smith-Lemli-Opitz syndrome - Tay-Sachs disease - Gaucher disease - Niemann-Pick disease - Mucopolysaccharidoses - Galactosemia + fructose intolerance - Hepatic (von Gierke disease) or Muscle (Pompe disease) - Sickle cell anemia - Alfa-thalassemia - Beta-thalassemia

Answer 384

X-linked recessive disease - daltonism – mutation in gene coding for rhodopsin (red-green colour-blindness) - nonspecific X-linked mental retardation - frequency 1/2 000 men - Fragile X syndrome - frequency 1/4 000 men, belong to dynamic mutations (non-Mendelian), mental retardation

Answer 385

- Duchenne and Becker muscular dystrophy (DMD a BMD) – diseases have a different site of deletion of the same gene o Progressive muscular atrophy, affects mainly men o mutated gene for dystrophin, which leads to the breakdown of muscle fibre, cause of death is usually heart failure § dystrophin has the longest gene and several tissue specific promotors § ensure the attachment to the extracellular fibres – ensure the communication between the inside and outside o muscular fibres die and are replaced by connective tissue; o problems walking from a young age, begin to walk later, cannot jump, need support when standing up o Duchenne - frequency 1/3 500 men § Upper variant – effects the dystrophin connection site for actin § Manifestation in early childhood, death around 20 years old § Muscle fibrosis § 33 % mutation de novo o Becker - frequency 1/20 000 men § Milder variant, disease effects sites in the central region of the protein, where it is hidden, onset at 11 years

Answer 386

X-linked coagulation defects - Haemophilia o No coagulation due to no or insufficient formation of coagulation factors (total 12) VIII or IX o First signs manifest when the concentration of coagulation factors decreases below 10% of standard level, under 1% is considered severe o Pathological phenotype – less than 5 % coagulation factor o Spontaneous bleeding post mild traumas, bleeding into joints and GIT § Bleeding into large joints -> arthrosis -> hemarthrosis o haemophilia A - frequency 1/5 000 men; deficiency of coagulation factor VIII o haemophilia B - frequency 1/35 000 men; deficiency of coagulation factor IX o there is also Haemophilia C, AR (4. chromosome), very rare and deficiency of coagulation factor

Answer 387

X-linked dominant disease - Vitamin D resistance rickets (hypophosphatemic rickets) o Practically no longer exists nowadays o Kidneys have an impaired ability to reabsorb phosphate, which causes abnormal ossification

Answer 388

Gene interactions are basically polygenic inheritance, for one trait, two or more genes are involved - Monogenic inheritance - 1 trait = 1 gen, genes segregated independently on each other - Polygenic inheritance - 1 trait = 2 and more genes, which affect each other via gene interactions o Polygenic disorder – influenced by more than one gene o Genotype ratio like in dihybrids, but less phenotypic diversity – due to gene interactions - Types of gene interactions 1) reciprocal interactions 2) epistasis (dominant and recessive) 3) inhibition 4) complementarity 5) multiplicity

Answer 389

Alleles of two or more genes contribute to the phenotype. Each possible combination of these alleles has a separate phenotype - analogue of incomplete dominance – more genes, each determining a different phenotype final phenotype is the mixture of all o e.g.: flower has 3 genes for determining colour with reciprocal interactions, one gene is green, second is red, third is blue. When these 3 colours mix, we get white à flower is white - interaction without the change of phenotypic ratio of Mendelian inheritance = phenotypic categories do not mix

Answer 390

relationship of superiority and subordination - epistatic gene suppresses phenotype manifestation of hypostatic gene genu - unilateral relationship o between alleles of two genes (M > N) o between alleles of more genes (M > N > R > S)

Answer 391

eye colour and hair colour

Answer 392

eye colour and hair colour

Answer 393

ABO blood group system

Answer 394

- similar to dominant epistasis, except that dominant epistatic allele has no effect itself on the phenotype, can only inhibit the effect of hypostatic alleles

Answer 395

bilateral relationship between alleles of interactive genes, no superiority/subordination; genes operate on the same level

Answer 396

bilateral relationship of alleles of interactive gene, but unlike for complementarity one dominant alleles in any one these genes is enough for it to become expressed in a trait - types of multiplicities o noncumulative – for full expression of trait, one dominant allele is needed, others are not needed and do not change the phenotype o cumulative – intensity of phenotype depends on the number of alleles present; one allele is enough for phenotype to become expressed and any if any other are present they intensify the phenotype. It is further divided into dominant / without dominance o during duplicity gene interactions, genes are not qualitatively different

Answer 397

Polygenic inheritance – certain trait is inherited through numerous genes which have a small and additive effect on the phenotype o These genes have an additive effect -> during the formation of the trait they are added up ( the more genes the stronger the trait/disorder)

Answer 398

multifactorial (complex) inheritance – when genes interact with environmental factors

Answer 399

effect of genes is not enough to cause the disorder -> people have predispositions, but not all effected will manifest the disorder, environmental factors also play a role

Answer 400

interrupts the development of fetus -proliferation, distribution, migration and integration of cells, reduction of excessive parts (e.g. in-between fingers – first a mass of cells, then cells die (apoptosis) forming spaces between our fingers, giving them shape - morphogenetic system = processes of embryo development o embryonal – organs and organ systems o fetal – organ components o perinatal – integrated systems (nervous, endocrine, immune) o postnatal - haematopoiesis, immune system

Answer 401

Hardy-Weinberg Law - the assumption is that there are only 2 alleles in the population – standard allele A and mutated allele a - frequency(A) = p frequency(a) = q - frequency of both alleles = p + q = 1 - frequency of genotypes = p2 + 2pq + q2 = 1 - Hardy-Weinberg law says that gene and genotype frequencies remain the same across generations – under the condition that the frequency of alleles does not change (population is in equilibrium)à e.g. if we know that 10% of population is heterozygote, we can mathematically prove that under generations this value does not change - X linked genes in males – frequency of alleles = frequency of genotypes = p + q = 1 o Man affected with X linked disease = q o Woman affected by X linked dominant disease = q o Women affected with X linked recessive disease = q2

Answer 402

Conditions of Hardy-Weinberg equilibrium 1) random mating 2) no mutations 3) no selection (natural or artificial) 4) no migration 5) population is large enough, for there to not be a genetic drift if there is selection and mutation and still everything is in equilibrium, law still applies

Answer 403

Non-random mating - Assortative mating - = non-random mating, choice of mate - Stratification of population – population divided into subgroups (ethnics) -> due to stratification, pairing is limited to certain groups - consanguinity = extreme cases of selective pairing, where there is an increased risk of polygenic AR disease o risk of being affected by AR disease in a marriage between relatives is F * q (F = coefficient of interbreeding, q = frequency of alleles in population)

Answer 404

consanguinity leads to the decrease of heterozygotes and increase of homozygotes

Answer 405

genetic drift – alleles can disappear randomly, 50/50 inheritance of alleles, can happen that one allele is not inherited in a generation and is lost

Answer 406

founder effect – if in a small group of founders of a large population is a carrier of a rare allele, this allele will after many generations have a higher occurrence in the population

Answer 407

congenital numerical – gene mutation o aneuploidy – one chromosome missing or in addition § trisomy 2n+1, monosomy 2n-1 o polyploidy – multiplication of haploid set § lethal – abortion, if children are born, they will die soon after birth, § triploidy 3n, tetraploidy 4n

Answer 408

congenital structural o balanced – no genes missing or in addition, only their rearrangement § Robertsonian translocation, reciprocal translocation, inversion o unbalanced – genes missing or in addition § deletion, duplication, ring/dicentric/izo-chromosome

Answer 409

acquired – via mutagens (clastogenes) and time, abnormalities in small amounts are found in all of us o mutations do not occur in all cells

Answer 410

chimaera – formed by the fusion of two zygotes – what should be dizygotic twins is joined to form one large zygote, this individual will have genes of zygote 1 and genes of zygote 2 o karyotype 46, XX/46, XY or 46, XX/46, XX -> from two zygotes (oocyte + sperm / polar body + sperm)

Answer 411

mosaic – one of the first cell divisions of a zygote is faulty and the individual with a mosaic will have 2 cell lines only with a slightly different karyotype o formed from one zygote (either normal or abnormal)

Answer 412

3 possible ways 1. egg + 2 sperm („dispermy“, 23 + 23 + 23 = 69 chromosomes) - partial mole 2. diploid egg + sperm (46 + 23 = 69 chromosome) 3. egg + diploid sperm (23 + 46 = 69 chromosome) - partial mole - triploidy is lethal, if a child is born it will die soon after - triploidy is most commonly formed by dispermy

Answer 413

partial mole – in a way a tumour (rarely malignant) o a mass of overgrown trophoblast with some tissue o triploidy fetus with extra paternal chromosomes (1 maternal, 2 paternal) - complete mole – formed by the fertilization of an enucleated (no nucleus) egg, only paternal genome o hypertrophic trophoblast, villi filled with fluid

Answer 414

mechanism of endoreduplication, which is the separation of chromosomes without the division of cell - 92 chromosomes (4 sets of chromosomes); formed postzygotically

Answer 415

ovarian teratoma – duplication of chromosomes and division of unfertilized ovum (diploid) o results in benign tumour which may have teeth and hair; only maternal genome

Answer 416

in meiosis – undivided homologous chromosomes in M1 or sister chromatids in M2 o abnormal disomic (diploid) / nullisomic (empty) gamete -> fertilization -> trisomy / monosomy - in mitosis - undivided chromatid into daughter cell, resulting in a mosaic

Answer 417

nondisjunction of 21 occurs 4x more often in oogenesis than spermatogenesis and at the same time 4x more often in M1 than M2 - internal causes – individual risk of individual chromosomes to nondisjunction; increases with age of women above 35 and men above 50 o in women above 35 – error in M1 – aging of egg, dysfunction of mitotic spindle, changes in intracellular environment (due to decrease of hormonal function) and accumulation of mutagens during women’s life § error in M2 – delayed fertilization due to over matured egg - external causes – external mutagens - not main factors of nondisjunction

Answer 418

loss of chromosome from trisomic gamete - e.g. cell of Down syndrome 47, XX+21 in its early stage of development loss of 1 chromosome 21, which leads to two daughter lines – one with down syndrome one healthy 46, XX - similarly, monosomy can form – if healthy cell loses a chromosome, suddenly there are 45

Answer 419

monosomy X – only monosomy suitable for life (even though 99% of cases are aborted) - autosomal monosomy – always lethal, always early spontaneous abortion (mother is not even aware of her pregnancy) - autosomal trisomy – only some have a chance to be born – trisomy 21, 18, 13 a mosaic 8 o other autosomal trisomies were described only in abortions (16. Is the most common)

Answer 420

Down syndrome (+21) Edwards syndrome (+18) Patau syndrome (+13) Turner syndrome (45, X; ...) Klinefelter syndrome (47, XXY; ...) Syndrome three X (47, XXX) Syndrome two Y (47, XYY)

Answer 421

except for Robertsonian translocations everything attributes to clastogenes (= mutagens causing chromosomal aberrations) - can occur anytime between G1, S, G2 and M phase as a result of bad (or no) correction of DNA breaks - can be balanced/unbalanced and congenital/acquired o balanced – abnormal rearrangement without the loss of genetic material o unbalanced – genetic material is missing or gained o congenital – in all types or cells or a large majority o acquired – only in a few cells - obtained chromosomal aberration are detected after cultivation of human peripheral lymphocytes

Answer 422

- all are connected with congenital disorders, mental retardations and abnormal development - deletion, duplication, ring chromosome, dicentric chromosome, Isochromosome, additional marker chromosome

Answer 423

partial monosomy - loss of genetic material - terminal deletion – cleavage of end part of chromosome - interstitial deletion when there are two breaks on one arm and a loss of genetic material between them o to place a segment from the fist chromatid into the sister chromatic through “loops” (G2) - break mostly occurs in G1 - uneven crossing-over, segregation error in meiosis - e.g. deletion Xp = small stature, patient is still fertile

Answer 424

partial trisomy - duplication or insertion of a segment from a sister chromatid from unequal crossing over - segregation in meiosis

Answer 425

2 breaks in G1 – at terminal sites of p and q, newly formed chromosome connected both ends and form a circle (ring) - patient with Turner syndrome most likely had a ring chromosome which has been lost and now they have X-

Answer 426

two breaks of two chromosomes in G1 and the connection of their ends in G2 - translocation dicentric (left) – connection of two centric fragments and two acentric fragments – these two chromosomes are non-functioning and unstable - isodicentric (right)- breakage of both chromatids and their connection, then inactivation of one centromere, formation of a pseudodicentric (exists and has been found in humans)

Answer 427

transverse division in the centromere in M2/mitosis, there is a duplication of one arm and the loss of the other - if Xp is lost in women, woman has an X Isochromosome, is still fertile but has a small stature

Answer 428

marker is an extra and small chromosome - to find the origin we use FISH method - can, but does not have to have clinical consequences

Answer 429

do not have an effect on the phenotype (even though the arrangement is different, the genetic material remains the same there is none missing or any extra present) - problems occur after reproduction, carriers create unbalanced gametes (parent is fine but child is affected) - men can be sterile (oligospermia – lower concentration of sperm in ejaculate) due to a disorder in pairing homologous chromosomes in meiosis - women can cause the transfer of an extra chromosome 21 onto their child - translocation causes the formation of derivative chromosome - Robertsonian translocation (Rob t) Reciprocal translocation (rcp t) Inversion (inv)

Answer 430

exchange of chromosomal segments of two nonhomologous acrocentric chromosomes during meiosis - acrocentric chromosomes (13,14,15, 21, 22) have long arms (q) significantly longer and they are more important than short arms (p) - if two long arms fuse, nothing happens, because short arms are not that important - resulting chromosome is the fusion of two chromosomes but is inherited as one, which causes Robertsonian translocation syndrome - carrier of balanced nonhomologous Rob t creates 6 types of gametes

Answer 431

includes two non-homologous chromosomes - one break in each chromosome - both chromosomes then exchange segments which have been broken off - empirical risk - women 10 %; men 2-5 % - 4 chromosomes can pair in a quadrivalent – problems after separation o T1, T2 - N1, N2 = alternate -> balanced + normal gamete o T1, N2 - T2, N1 = adjacent 1 o T1, N1 - T2, N2 = adjacent 2 unbalanced gamete with duplication and deletion

Answer 432

transfer of genetic material within one chromosome - two types, depending on if the rotating part contains centromere or not - pericentric – breakage on small or long arm, centromere also rotates - paracentric – two breaks on one arm, no centromere involved - since the sequence of genes is inverted in that part of the chromosome, chaos can occur when pairing homologous chromosomes o risk of recombination increases with the size of the inverted segment

Answer 433

- segregation of unbalanced genome (= disabled child / abortion) - sterility (mainly in men) - in women with aberrant chromosomes they prefer to put these chromosomes into polar bodies, that is why they are more resistant to sterility - phenotypic effect – small deletion, inversion or wrong arrangement of genes can lead to dysregulation of gene expression, aberration will be expressed

Answer 434

postnatal- specific phenotype, psychomotoric retardation, growth disorder, malformation, limb swelling, sterility, delayed puberty, no menstruation in women, malformation of genitals, is family relatives have aberrations - prenatal- increased age of mother (35+ at time of birth), pathological values of markers, abnormal ultrasound, aberration in at least one parent

Answer 435

- Ordinary mechanism of gene expression - Mendelian genetics presumes the same expression of homologous alleles inherited from mother and father - imprinting does not obey this rule – it is a genetic phenomenon, where the level of gene expression depends on whether it was inherited from mother or father - imprinted genes are transcribed only from one allele of a specific parent (the other is inactive) - inactive allele is called imprinted o Imprinted genes, are genes which are needed at the beginning of development (embryonic development, regulation of cell proliferation), however only one active allele must be present, not two, one needs to be inactive - As the mechanism of inactivation is methylation during gamete formation, it is an epigenetic inheritance and an epigenetic mechanism of gene expression regulation (this means errors or mutation in this process are pathological)

Answer 436

At the beginning of embryonic development imprinted gene which prefer paternal genes, help form the placenta (trophoblast). Imprinted genes which prefer maternal genes help in the development of embryo o This is why human parthenogenesis -> we need the genes of sperm and egg - Examples of pathology: o Triploidy with additional paternal set of chromosomes (diploid sperm + egg / two sperm (dispermy) + one egg) leads to hyperplasia of trophoblast and reduced embryo (partial mole) o triploidy with extra maternal set of chromosomes (sperm + diploid egg) small placenta formed o if sperm fertilizes egg with no chromosomes inside (enucleated), division of only male pronucleus => only placenta, no embryo (complete mole) o if egg starts to divide without fertilization, only maternal genes present no paternal only embryo and no placenta (ovarian teratoma) – benign tumour, can grow teeth and hair

Answer 437

- PWS symptoms include: obesity, small stature, hypogonadism and mental retardation o caused by the absence of PWS genes, which are inherited from father (mothers are imprinted = inactive) - AS symptoms include: dysmorphic features, problems with sleep, slim figure, mental retardation and uncontrolled inappropriate laughter o caused by the absence of AS genes, which are inherited from mother (fathers are imprinted = inactivated) - genes for PWS and AS are on long arms of chromosome 15, right next to each other

Answer 438

also, known as EMG syndrome (Exomphalos-Macroglossia-Gigantism) - Beckwith-Wiedmann syndrome symptoms may include abdominal wall defects, macroglossia, gigantism, enlargement of organs, neonatal hypoglycaemia and increased risk of tumours – e.g. Wilms tumour - Reciprocally imprinted genes are next to each other on 11p15 IGF2 (expression of paternal allele) and H19 (expression of maternal allele) - Same problem as in PWS and AS -> duplication, deletion, uniparental disomy (UDP), translocation or faulty imprinting can lead to a different state than the normal physiological one (1 active allele IGF2 and 1 active allele H19) and every abnormality of this type causes Beckwith-Wiedmann syndrome

Answer 439

Main mechanism of imprinting is methylation, which closely links with proto-oncogenes and tumour suppressor genes - proto-oncogenes – for expression need both alleles active, if one allele is imprinted, the whole gene is disabled o if an inactive allele becomes demethylated (loss of imprinting), the proto-oncogene is turned into an oncogene and tumour forms - tumour suppressor genes o if accidental imprinting of one tumour suppressor gene occurs, the loss of the second healthy allele will cause tumour development à imprinting of tumour suppressor genes means high predisposition to tumours o e.g. WT1 (11p13, more below) § IGF2R (6q26) – gene of receptor for IGF2 (insulin-like growth factor 2), marks IGF2 for degradation, however if there is no receptor, IGF2 is not degraded and cell continues to receive signals to grow - methylation is however reversible - methylation and demethylation is studied as one of the possible cures in cancers

Answer 440

malignant tumour of kidneys/kidneys of small children (max. 3 years old) - locus 11p13 – associated with WAGR o WAGR = genetic syndrome, predisposition for Wilms tumour, Aniridia (absence of iris), Genital anomalies and mental Retardation o WT1 – tumour suppressor gene, if imprinting occurs – predisposition to tumours - locus 11p15 – associated with BWS -> high no. copies of growth gene IGF2 o gene IGF2 (from father) codes for IGF2 (insulin-like growth factor 2), if there are more genes -> more IGF2 -> more growth -> BWS o deletion or translocation of maternal alleles H19 causes activation of maternal allele IGF2

Answer 441

inheritance of 2 homologous chromosomes from one parent - mechanisms of UPD origin o loss of chromosome in trisomic gamete o gametic complementation – fertilization between nullisomic and disomic gametes o duplication of single chromosome in monosomic gamete o postzygotic nondisjunction and duplication or mitotic recombination - results of UPD - abnormality in the case that chromosomes contain imprinted genes

Answer 442

dynamic mutation mutation in promotor for gene FMR1 (Fragile X Mental Retardation 1) on X chromosome, most commonly increased number of CGG trinucleotides in 5’ promoter region FMR1 o cause of mutation – instability of specific microsatellite repeats

Answer 443

amplification in noncoding regions (promotor, intron) o usually loss of function or abnormal splicing o Fragile X syndrome (CGG) – in promotor, myotonic dystrophy (CTG) – in introns, Fredrich ataxia (GAA) – in introns - Amplification in exon o usually CAG (glutamine) leads to abnormal protein (Polyglutamine disorders) o Huntington disease - abnormal protein huntingtin and inactivation of associated proteins § progressive neurodegenerative disease, manifestation of disease at around 35 years of age – usually after reproduction and sooner if carried by father (this will be in the statements) o Spinocerebral ataxia - neuromuscular disorder, retinal degeneration

Answer 444

homogeneity – there are no more alleles therefore allelic heterogeneity does not exist - does not obey Mendel’s inheritance - expressivity, penetrance - there is no new mutation – formation is gradual through premutations – familiar diseases - postzygotic origin of amplification on maternal chromsome – determined in oogenesis<

Answer 445

Cultivation of peripheral blood lymphocytes - from peripheral blood (from blood vessels), which we take into heparin syringes after cultivation, we add colchicine to the mixture which stops cell division in metaphase (acts on the mitotic spindle) - following that is centrifugation

Answer 446

specific phenotype - physical defects - infertility - delayed puberty, - examination of parents and relatives if a chromosomal abnormality is found

Answer 447

Cultivation of amniotic fluid (most reliable) Cultivation of chronic villi cells Cultivation of fetal blood Examination of free fetal DNA from mother’s blood

Answer 448

increased age of mother 35 or more during time of birth - pathological value in biochemical markers in maternal blood abnormal finding in an ultrasound - e.g. abnormal amount of fluid, nasal bone ... - carrier of balanced chromosomal aberration in at least one parent - psychological indication

Answer 449

an accurate visualisation of constitutive heterochromatin a centromere

Answer 450

FISH = Fluorescent In Situ Hybridization First, we need to produce a probe - A probe is a short sequence of nucleotides, to which fluorescent dye is attached types of probes o α-satellites – detect the centromeres of specific chromosomes – ideal for counting in non-dividing cells (detects aneuploidies; chromosomes of unknown origin) o locus-specific – on specific loci of a chromosome – ideal for the detection of microdeletion, oncogenes, fused o painting – paint the whole chromosome – good for the detection of aberration or rearrangement of chromosomes - FISH method can be used during interphase; in tumours, each pairs stain differently

Answer 451

Microarray analysis (Array CGH) this method detects unbalanced aberrations

Answer 452

chromatid aberrations – typical aberrations after the effect of chemical substances o chromatid breaks, chromatid exchanges - chromosome aberrations – typical aberration after radiation o chromosomal breaks, deletion, translocation, ring, dicentric chromosomes o effects both chromatids

Answer 453

diagnostic irradiation Hyperthermia Mechanical causes

Answer 454

food, medicines and drugs - proved teratogens in 1rst trimester vitamin A warfarin cytostatic fat soluble vitamins thalidomide -drugs cigarettes, cocaine and LSD caffeine alcohol

Answer 455

viruses (varicella, rubella, herpes, influenza, viruses), bacteria (syphilis) and protozoa

Answer 456

- primary prevention – to prevent the origin of inborn defects - secondary prevention - control over pregnancy, if a disorder has not developed and if yes, recommend a treatment or terminate pregnancy - tertiary prevention – after birth, prevention of disorder complications

Answer 457

Biochemical processes - transport of electrons, oxidative phosphorylation, photosynthesis - Information processing – transmission of nerve impulses, effects of hormones - compartmentalization biological pathways

Answer 458

saturated o palmitic acid - hydrophobic o stearic acid- hydrophobic - unsaturated o have a coiled side chain, due to cis double bonds, which keeps the membranes in a fluid state § as they are deformed due to cis bonds, they cannot effectively stick together o linoleic acid, arachidonic acid - ω-6 fatty acids, essential o linolenic acid - ω-3 fatty acids, essential

Answer 459

phosphatidic acid= 2 FA + glycerol + phosphoric acid o precursor of all TAG and most phospholipids o FA are bound to glycerol via ester bound - Own glycerophospholipids are formed by binding another component to phosphatidic acid o We add a base containing nitrogen - types glycerophospholipids o phosphatidylcholine (lecithin) – formed by the attachment of choline § main component of membranes (90 % in new-borns) o phosphatidylethanolamine o phosphatidylserine o phosphatidylinositol - phosphatidylinositol phosphate

Answer 460

cholesterol – in membranes mainly in non-esterified form

Answer 461

movement of solvent molecules across a semipermeable membrane from an area of low solute concentration to an area of higher solute concentration

Answer 462

membrane potential is formed by the different concentration of ions inside and outside the cell – inside mainly negative charge, outside positive - inside - K+ and negatively charged proteins - outside - Na+ a Cl- - two forces apply here o electrical – because all molecules are charged, they attract or repel each other - K+ and Na+ want to go in, Cl- and proteins want to go out o concentration - K+ and proteins want to go out, Na+ and Cl- want to go in o when these two forces are put together, they form an electrochemical gradient - because K+ want to go in (due to the electrical force) but even out (due to the concentration gradient), these two forces will compete and K+ will partly leak out of the cell causing a more positive charge outside than inside

Answer 463

passive – via concentration gradient o Facilitated diffusion- e.g. glucose carriers - active - against concentration gradient o e.g. taking in glucose from intestines (cotransport of glucose with Na+) o takes part in maintaining the osmotic balance o regulated by pumps driven by the hydrolysis of ATP – meanwhile cleaving ATP to ADP and phosphate

Answer 464

Diffusion of substances across membranes is selective: small hydrophobic molecules (including gas molecules) and small uncharged polar molecules (including H2O)

Answer 465

Uniport: transport of one type of molecules Symport (coupled transport): cotransport of two types of molecules in the same direction * Antiport (coupled transport): contransport of two types of molecules in opposite directions

Answer 466

Passive uniport (along concentration gradient): facilitated diffusion (transport of amino acids, glucose: GLUT1) * Active uniport: ATPases (ATP-driven pumps: Ca2+ pump)

Answer 467

Passive symport (rare: Na+ -Cl- symport in frog stomach) * Active symport (glucose pump)

Answer 468

Passive antiport: exchange diffusion (chloride-bicarbonate exchanger: Cl-/HCO3-, erythrocytes * Active antiport (Na+-K+ pump)

Answer 469

channels facilitating water diffusion across plasma membrane

Answer 470

Ligand-gated ion channels: opening is regulated by ligand binding * Voltage-gated ion channels: opening is regulated by the change of voltage on the membrane

Answer 471

Transport through nuclear pores (gated transport): transport of proteins and RNAs into and from nucleus and cytosol * Transport across organelle membrane: transport of proteins across organelle membrane (mitochondria, ER) by protein translocators * Transport of vesicles (vesicular transport): transport of vesicles filled with transported molecules within the cell * Transport of whole organelles: transport of organelles within the cell along cytoskeletal filaments mediated by motor proteins

Answer 472

Receptor- mediated endocytosis: clathrin-coated pits endosomes 2 basic types of endocytosis: * Pinocytosis: small vesicles of fluids and molecules * Phagocytosis: larger particles (microorganisms, cell debris)

Answer 473

Extracellular matrix: system of protein and polysaccharide molecules filling intercellular space. Main types of macromolecules of extracellular matrix: * Proteins: * fibrous proteins * glycoproteins * Polysaccharides: glycosaminoglycans (GAG) & proteoglycans Functions of extracellular matrix: * It fills intercellular space. * It determines mechanical and other physical properties of the tissue.

Answer 474

Extracellular matrix represents basic component of connective tissue. Cells of connective tissue producing extracellular matrix: * Fibroblasts (most of connective tissues) * Chondroblasts (cartilage) * Osteoblasts (bone)

Answer 475

Fibrous proteins: * Collagens: triple helixes, fibrils, fibers they contain hydroxyamino acids: hydroxylysine and hydroxyproline procollagen, collagenase (defect in procollagen or collagenase) (skin, tendon, bones) * Elastin: elastin fibers (arteries)

Answer 476

Fibronectin: dimer (bonding to collagen) Laminin: trimer (bazal lamina)

Answer 477

Glycosaminoglycans (GAG): disaccharide subunits (amino sugar + uronic acid) unbranched polysaccharide Main types of glycosaminoglycans: * Hyaluronan (it does not contain sulphate) * Chondroitine sulphate * Dermatane sulphate * Heparane sulphate * Keratane sulphate

Answer 478

Proteoglycans: core protein and attached polysaccharide fibers Examples of proteoglycans: * Decorin (common in connective tissues) * Aggrecan (cartilage) * Perlecan (basal lamina) Aggregates of proteoglycans with GAG

Answer 479

Cell junctions: protein structures connecting the cell with another cell or the cell with extracellular matrix Function of cell junctions: * Mechanical connection of cells * Attachment of cells to extracellular matrix * Communication between cells Functional types of cell junctions: * Occluding cell junctions * Anchoring cell junctions * Communicating cell junctions

Answer 480

Function: sealing the space between cells Types of occluding cell junctions: * Tight junctions: claudins, ocludins Sealing strand (zonula occludens)

Answer 481

Function: interaction cell-cell interaction cell-extracellular matrix Types of anchoring cells junctions: * Junctions bound to microfilaments * Junctions bound to intermediate filaments

Answer 482

Adherens junction: interaction cell - cell cadherins Adhesion belt (zonula adherens) Focal adhesions: interaction cell - extracelullar matrix integrins

Answer 483

Desmosomes : interaction cell - cell cadherins (desmoglein, desmocolin) Cytoplasmatic plaque (plakoglobin, desmoplakin) * Hemidesmosomes: interaction cell - extracellular matrix integrins

Answer 484

Function: communication between cells Types of communicating cell junctions: * Gap junctions: connexon, connexin

Answer 485

Selectins: proteins on cell surface (they bind saccharides) transient cell-cell adhesions in the bloodstream

Answer 486

polylinker - artificial fragment of DNA with specific spots for restriction endonucleases (RE), which allow to incorporate gene of interest - transgene into cell - origin of replication - selection marker - genes for resistance to two or more antibiotics.

Answer 487

monoclonal antibodies – immunoglobulins formed from one B lymphocyte clone, are identical and work against a specific antigen

Answer 488

we need a stable and replicating DNA molecule - cloning vector needs to have an origin of replication, one/more restriction sites and selective markers - bacterial plasmids - small circular DNA molecules replicating outside their own bacterial chromosome o not ideal vectors for the transfer into mammal DNA (viruses are better) - bacteriophage lambda, bacteriophage M13 - cosmids – combination of phage and plasmid, circular molecule - viruses – retroviruses are used for the transfer of therapeutic genes into the mammal cells. o Older types of virus vectors used to transfer genetic information during gene therapy into the genome almost randomly, transferred genes would then disturb sequences of other genes - restriction endonuclease (enzyme type II, also used in PCR) – enzyme cleaves DNA at specific sites (4-8bp) – palindromes (gene palindromes can be read in both directions) o these enzymes have bacterial origin - PCR – method of sectioned DNA replication

Answer 489

injection of gene of interested into the pronucleus of fertilized egg (shortly after fertilization the egg has 2 nuclei – one male and one female which are then fused; these haploid nuclei are called pronucleus) - transgenic mice can carry foreign genes, which have been introduced into a germ cell - this method also helped prove that the SRY gene is responsible for the male gender

Answer 490

cell which can give rise to a highly-differentiated cell type - can be obtained by the reprogramming of somatic cells (introducing retroviruses with reprogramming genes) - are embryonic or infant and adult – bone marrow, peripheral blood, umbilical cord d - stem cells can undergo unlimited asymmetric mitotic divisions, thereby regenerating - during transplantation have the ability to reintegrate into the tissue of their origin - can be created by nuclear transfer

Answer 491

multipotent – can develop into a limited number of cell types in a particular lineage. Differentiate into a limited range of cells o unipotent – ability of a cell to develop into only one cell type (spermatogonia, used for infertility treatment) o pluripotent – can give rise to all cell types of the body (but not the placenta) o totipotent – are capable of differentiating into an unlimited number of specialized cell types (includes zygotes and cells of 4-8 cell stage of early embryo)

Answer 492

A piece of organ removed from living organism (eg during surgery (BIOPSY)‏ from dead body (NECROPSY)‏

Answer 493

Fixation stops metabolic processes within the cell (by slowing down action or denaturation of enzymes) Physical methods: Heat (microwave)‏ Freezing (liquid nitrogen – 170 oC)‏ Chemical methods: Immersion of samples into fixation fluid‏ Perfusion, ie. injection of fixation fluid into vessels

Answer 494

sampling -> fixation -> embedding -> cutting -> staining -> done, permanent slide

Answer 495

fixation stops the metabolic pathways in the cell by slowing them down or via enzyme denaturation - physical methods - heat (microwave) or cold (liquid nitrogen, -170°C, is used more often as it is faster) - chemical methods - immersion (immersion into fixation liquid) or perfusion (fixation fluid is introduced into the blood)

Answer 496

after cutting it is necessary to harden the tissue by embedding it - paraffin, celloidin - paraffin nor celloidin can mix with water, therefore it is necessary to remove water from the tissue via alcohol and then impregnate the tissue with further solvents of embedding medium (xylene, toluene, acetone) which „brighten” the tissue up, procedure is called “clearing”

Answer 497

mixture of dye, which stain the tissue in a large spectrum (most commonly on the basis of affinity towards acidic or basic substances) - haematoxylin-eosin o dark purple haematoxylin stains acidic (basophilic) parts of cell – DNA & RNA (nucleus, nucleolus, ribosomes, RER) o light pink eosin stains basic structures of cell (acidophilic, eosinophilic) – mainly proteins (cytoplasm, MIT, SER) - Weigert-van Gieson –connective tissue is red; cytoplasm is orange - AZAN – nucleus of erythrocytes is red, collagen fibres and mucin are blue, cytoplasm and muscle are orange - green Masson trichrome – muscle red, collagen fibres green, nucleus blue-purple-black, Ery red

Answer 498

stains only one component (elastic fibres, reticular fibres) - Weigert resorcin fuchsin o Selective staining for elastic fibres – stains them purple - Heidenhain iron haematoxylin o Stains nuclei and cytoplasm grey-black o Used to stain muscle and in parasitology for detection of parasites (worms) in tissue - silver impregnation o silver stains collagen and reticular fibres brown to black o used also in the staining of neurons and glia in neurohistology

Answer 499

elements - Hg, Pb, Fe, Ca, Zn and their salts - Perl’s reaction – detection of Fe2+ in macrophages and spleen o Fe2+ + 2% HCl + potassium ferrocyanide - Prussian blue is formed

Answer 500

Small organic molecules, which are known to bind specifically to our target molecule § Phalloidin – binds to filaments of F-actin § DAPI and ethidium bromide – binds to DNA § paclitaxel – binds to molecules of tubulin

Answer 501

direct detection – marked primary antibody o for the detection of protein, we add an enzyme. The final product shines - Indirect detection – non-marked primary and marked secondary antibody o Primary antibody is recognized by secondary antibody, the enzyme is on the secondary antibody o more than one seocndary antibody can bind onto the primary antibody which leads to amplification of signal

Answer 502

methods based on immunodetection - ELISA, flow cytometry, SDS-PAGE + Western blot o SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) – method which is used to separate proteins according to their molecular weight

Answer 503

a substance dissolved in a solvent in forming a solution

Answer 504

a liquid that dissolves another substance or substances to form a solution

Answer 505

M = mol/1000 mL 1M solution ⇒ 1 mol of a solute is found in 1000 mL (= 1L) of the solution 0,5M solution ⇒ 0,5 mol of a solute is found in 1000 mL (= 1L) of the sol.

Answer 506

1% solution ⇒ 1g of a solute is found in 100 g of the solution 0,5% solution ⇒ 0,5g of a solute is found in 100 g of the solution

Answer 507

Molarity (c) (mol x l-1 = mol x dm-3 = M ) = number of moles per liter of a solution c=n/v

Answer 508

Hypotonic has a lower concentration of fluid, sugars and salt than outside. Hypertonic has a higher concentration of fluid, sugars and salt than outside Isotonic has similar concentration of fluid, sugars and salt to outside

Answer 509

osmotic pressure of coloidal solutions, e.g. proteins

Answer 510

Atomic number = number of protons in nucleus Atomic mass number = number of protons + neutrons

Answer 511

1 mol is equal to 6.022x1023 particles (atoms, molecules, or ions)

Answer 512

0.85 % w/v solution contains 0.85g in 100 mL 1L will contain 8.5g of NaCl As Mr (NaCl) is 58.44 we can easily calculate how many moles is in 8.5g: 8.5/58.44 Molarity is 0.14 mol/L

Answer 513

pH = - log c(H3O+)

Answer 514

pKW = pH + pOH = 14 pK = - log K pH = - log [H3O+] pOH = - log [OH-]

Answer 515

= solutions which have the ability to absorb small additions of either a strong acid or strong base with a very little change of pH. * buffers are used to maintain stable pH * composition of buffers: „conjugated pair: acid /base

Answer 516

pH = pKa + log (cs / ca) (for acidic buffer ) pOH = pKb + log (cs / cb ) (for basic buffer) pH = 14 - pOH

Answer 517

Buffer systems in extracellular fluid: * bicarbonate (hydrogen carbonate) system (HCO3-/ H2CO3) * hemoglobin (Hb/Hb-H+ acts as an intracellular buffer within erythrocytes * plasma proteins, phosphates, sulfates, organic anions ➢Buffer systems in intracellular fluid: * proteins * phosphates ➢Buffer systems in the urine: * phosphates (HPO42-/ H2PO4-) * ammonia buffer (NH3/NH4+)

Answer 518

1) 60% of mass: water (H2O) 2)organic compounds a) high molecular weight (proteins, nucleic acids, glycogen) b) low molecular weight (glucose, lipids, amino acid, intermediates of metabolism – often derivatives of carboxylic acids) 3. inorganic ions – minerals

Answer 519

propanol and ethyl methyl ether ARE isomers

Answer 520

structural isomers (different constitution of molecules) * different position of double bonds, cis-octadeca-9,12,15-trienoic acid cis octadeca-6,9,12-trienoic acid functional groups or side chains alpha- / beta-alanine leucine / isoleucine different order of atoms: different derivatives propanal / propanone glyceraldehyde / dihydroxyacetone keto-enol isomers (tautomers) bases of nucleic acids (e.g. uracil) pyruvate / enolpyruvate stereoisomers (different configuration in space) * cis-trans isomers (geometrical isomers) maleic acid / fumaric acid * enantiomers (optical isomers – mirror images) L-amino acid D-glyceraldehyde

Answer 521

propanal and propanone ARE isomers

Answer 522

yes they can

Answer 523

monocarboxylic acids formic acid, acetic acid, propionic acid,butyric acid fatty acids (often even number of carbons) * dicarboxylic acids oxalic acid, malonic acid, succinic acid,glutaric acid fumaric acid * benzoic acid

Answer 524

hydroxy acids lactic acid, malic acid, β-hydroxybutyric acid glyceric acid, citric acid (tricarboxylic acid) oxo acids pyruvic acid, oxaloacetic acid, acetoacetic acid, α-ketoglutaric acid amino acids γ-aminobutyric acid (GABA) all proteinogenic acids (21)

Answer 525

*alcohol group in a side chain serine, threonine, tyrosine * sulfur in a side chain cysteine, methionine * aromatic amino acids phenylalanine, tyrosine, tryptophan, histidine * branched-chain amino acids valine, leucine, isoleucine * acidic amino acids aspartic acid (aspartate), glutamic acid (glutamate) * basic amino acids lysine, arginine, histidine

Answer 526

anions (salts) lactate, malate, β-hydroxybutyrate, pyruvate, oxaloacetate, acetoacetate α-ketoglutarate, γ-aminobutyrate fumarate, citrate, glycerate * amides asparagine, glutamine * esters * anhydrides

Answer 527

C3 - glyceraldehyde (aldotriose), dihydroxyacetone (ketotriose); smallest saccharides, both are important intermediates of a human metabolism C5 - ribose, 2-deoxyribose (aldopentoses); components of nucleotides: found in nucleic acids (ribose in RNA, deoxyribose in DNA) C6 - glucose, galactose, mannose (aldohexoses), fructose (ketohexose); components of oligo- and-polysaccharides, metabolic intermediates

Answer 528

= oligosaccharides composed of 2 monosaccharides: * sucrose (= saccharose) consists of glucose and fructose * lactose (= milk sugar) consists of galactose and glucose * maltose (= malt sugar) consists of two glucoses

Answer 529

starch = storage polysacharide of plants, consists of linear amylose and branched amylopectin; it is a glucan = polymer of glucose * glycogen = storage polysaccharide of animal cells („animal starch“); it is a branched polymer of glucose (resembels amylopectin) * cellulose = structural polysaccharide of plants, linear, water insoluble glucan

Answer 530

isomers of saccharides differing in orientation of only one –OH group in space

Answer 531

purine nucleotides: contain adenine, guanine, (and hypoxanhine and xanthine = metabolic intermediates) * pyrimidine nucleotides: contain cytosine, uracil or thymine

Answer 532

Frequency of AR disease: q2 Frequency of AD disease: p2 + 2pq Frequency of X linked disease: for ♂ (males) p + q = 1 for ♀ (females) p2 + 2pq + q2 = 1

Answer 533

chemically and structurally heterogeneous substances Hydrophobic (and so poorly soluble in water and very well soluble in nonpolar solvents) Their molecules contain alcohols and fatty acids Their biosynthesis usually starts with acetyl-CoA

Answer 534

monocarboxylic acids (having 2 or more C atoms) Typically have odd number of carbon atoms *If they contain double bonds, they are usually isolated and in cis-configuration * Most of the fatty acids have 16 and 18 C-atoms

Answer 535

is a compound lipid found in the myelin sheath of the neurons.