Cells, Biological Molecules, Membranes, Enzymes (2) Flashcards
Benedict’s quantitative test: If the reading for the unknown glucose solution does not fit on the range of the calibration curve, i.e. suggests a concentration greater than 1%, what could be done to obtain an accurate value for its concentration
dilute the unknown eg. serial dilution, and then calculate the original eg. multiply.
formula of disaccharide sugar
C12H24O12 - H2O (condensation reaction) = C12H22O11
summarise the condensation reaction to form a peptide bond
The hydroxyl group in the carboxylic acid of one amino acid reacts with a hydrogen in the amine group of another amino acid. A peptide bond is formed, water is produced. Example of anabolism. Resulting compound is a dipeptide.

what are the advantages and disadvantages of laser scanning confocal microscopes (4+1)
ADV:
- >living things can be viewed –> movement observed*
- >3D images can be produced by using several focal planes (different depths of field) **
- >non-invasive eg. used in detection of eye diseases **
- >fluorescent staining allows structures to be compared*
- *not in light microscopes*
DISADV:
>lower resolution than electron microscopes (shorter wavelength because not using light)
which adaptations does an erythrocyte have specific to its function
CONCAVE SHAPE; LARGE SURFACE AREA; hbfadglbf
THIN MEMBRANE;
describe the structure of cellulose
Alternate beta-glucose monomers are upside-down in order for B-1,4 glycosidic bonds to form. This creates a straight chain.
Around 80 chains form H-bonds together to form a microfibril. Microfibrils form H-bonds to make a macrofibril, which in turn produce fibres. INTERmolecular H-bonds to support structure.

what are multipotent stem cells
cells that can produce only cells of a closely related family of cells
eg. haemopoietic adult stem cells in the bone marrow differentiate into erythrocytes, platelets, macrophages, neutrophils etc.
what is the function of the R group
to form different bonds with other amino acids, leading to the long chains of amino acids to fold in a certain way. This will affect secondary, tertiary and quaternary structure and therefore produce a specific protein.

what is potency for cells
it specifies the differentiation potential of the stem cell i.e. how many different types of cell a stem cell can become
why are enzymes important to organisms
they allow reactions to occur at the temperatures within cells. Otherwise, metabolic reactions would occur too slowly, and the organism would die.
they also allow fine control over rate of reaction.
name the polysaccharide in fungi and insects (+ where)
CHITIN in the exoskeleton of insects in fungi cell walls
what was the initial hypothesis for how enzymes work
the lock and key hypothesis; the active site is EXACTLY complementary to the substrate and during the reaction the active site does not change shape, allowing it to continuously bind to substrates, forming enzyme-substrate complexes

what is glucose + fructose
sucrose- transport sugar in plants
what are the axes for a calibration curve
y axis = % transmission of red light x axis = concentration of glucose
how is glucose stored in plants and fungi
-stored as two forms of starch.
the starch is in grains in amyloplasts in the cytoplasm of plant cells
-stored as glycogen in fungi
why are enzymes specific to one type of reaction only
each enzyme has a specific tertiary structure (the overall 3D shape of the enzyme, involving coiling and pleating of the secondary structure) that gives it a specific active site complementary to a specific substrate. The tertiary structure is ultimately determined by the primary structure.
what is a polymer
a chain of repeating units, monomers, linked by covalent bonds

what is an ‘organic’ molecule
one that contains C and H
name the fibre appearance and whether it is voluntary/involuntary, uni/multinucleate for each of the three types of muscle cell
SKELETAL = striated, voluntary
multinucleate
CARDIAC = striated, intercalated (branches), involuntary
uninucleate
SMOOTH = unstriated, spindle-shaped, involuntary
uninucleate

summarise the basic structure of an amino acid monomer
A carbon atom (C) bonded to a hydrogen atom (H), an amine group (NH2) (base), a carboxyl group (COOH) (acid), and a variable R group, of which there are 20, giving the 20 main essential amino acids in humans.

what is a carboxyl group and where are they found, what is their compound name
a carbon bonded to a hydroxyl group and double-bonded to an oxygen atom (—COOH) found in amino acids and triglycerides carboxylic acid is the compound name

what is a microscope
an instrument employing lenses to produce a magnified image and fine details of objects too small to see with the naked eye

how to calibrate a light microscope
an eyepiece graticule inside the microscope has no units. it remains unchanged whichever objective lens is in place
we use a stage micrometer to work out how many (um) are in each division on the eyepiece graticule

what is the structure of haemoglobin
two alpha-polypeptide chains and two beta-polypeptide chains
+ an inorganic prosthetic haem group
the haem group contains an iron atom in a porphyrin ring (chlorophyll anyone?)
it has an overall tertiary structure of mainly alpha-helices

what are the functions of Ca(2+), potassium K(+) and sodium Na(+) ions
Ca(2+) calcium ions nerve impulse transmission, muscle contraction Na(+) sodium ions nerve impulse transmission, kidney function K(+) potassium ions nerve impulse transmission, stomatal opening
what is the main property and formula of monosaccharides
they are soluble and have the general formula (CH2O)n where n is = or >3.
what are the bonds involved with the different levels of protein structure
primary- peptide
- secondary*- intramolecular hydrogen bonds
- tertiary*- hydrogen (weakest), ionic (form between oppositely charged R-groups), disulfide/covalent (bonds or bridges, strongest of all, only form between S-containing R-groups), hydrophobic/hydrophilic interactions (weak, between polar and non-polar R-groups)
- quaternary*- “ as tertiary: hydrogen, ionic, disulfide/covalent, hydrophobic/hydrophilic interactions

Benedict’s quantitative test: If the reading for the unknown glucose solution does not fit on the range of the calibration curve, i.e. suggests a concentration greater than 1%, what could be done to obtain an accurate value for its concentration
dilute the unknown eg. serial dilution, and then calculate the original eg. multiply.
what are the functions of H+ and NH4+ ions
H+ hydrogen ions catalysis of reactions, pH determination, chemiosmosis
NH4+ ammonium ions production of nitrate ions by bacteria

what are totipotent cells
cells that can differentiate into ALL types of cell
name and give one sentence describing the four parts of a sperm cell (spermatozoon)
- acrosome at top of head, contains hydrolytic enzymes to digest outer layers of ovum follicle to reach cytoplasm/nucleus.
- head contains haploid nucleus (n) for fertilisation of an ovum for subsequent production of diploid zygote (2n).
- midpiece contain large quantity of mitochondria to produce ATP by AR to provide energy for tail motion
- tail: flagellum/undulipodia contains contractile microtubule fibres to enable movement/swimming

measuring cells is done in…
micrometers (um)
what gives collagen added strength (i.e. not from its structure)
collagen molecules form staggered COVALENT CROSS LINKS with each other, forming more chains. Collagen molecules wrapped around each other from COLLAGEN FIBRILS (and then collagen fibres)
what are the functions of OH- and Cl- ions
- OH- hydroxide ions* catalysis of reactions, pH determination
- Cl- chloride ions* balance the positive charge of sodium and potassium ions in cells

what is the structure of an amino acid
a carboxyl group (–COOH attached to carbon skeleton) and an amine group (NH2 attached to carbon skeleton, a H attached to the C and a variable R-group attached to the C. The different R-groups result in different amino acids (of which there are 20).
what is fluorescence
the absorption and re-radiation of light
what are the 3 functions of intermediate filaments
-anchor the nucleus -allow cell to cell signalling eg. antigens, WBCs, ECM -allow cell to cell adhesion in tissues
what is the first monosaccharide
C3 H6 O5 = triose. eg. TP/GP in Calvin cycle/glycolysis
why is staining used with light microscopes
the interior of cells is often transparent
staining allows different components of cells to be distinguished between
provides contrast between structures
how can you describe the two parts of a phospholipid
The hydrophilic polar ‘head’ and the hydrophobic nonpolar ‘tail’

what are pluripotent stem cells
the descendants of totipotent cells
they can differentiate into cells derived from the three germ layers of endoderm, mesoderm, ectoderm
eg. ectoderm can differentiate into skin, nerves, hair
what is the limit of an optical microscope’s resolution
the resolution can be no greater than 0.2µm, because that is half the wavelength (400nm/0.4µm) of visible light.
Light waves can resolve objects greater than or equal to 400nm apart.
how is tertiary structure broken
increasing TEMPERATURE to increase kinetic energy, causing the bonds to vibrate and not maintain the shape of the protein and eventually break (they are not covalent so not very strong). Once it has lost its shape, a protein is DENATURED.
which cells can differentiate into all cell types
TOTIPOTENT stem cells

what is collagen
an insoluble fibrous protein
List the property, structure, type of bond, found in, and function of AMYLOPECTIN
P = insoluble, granular S = polysaccharide, branched TOB = a-1,4 glycosidic bonds and a-1,6 glycosidic bonds, intramolecular H-bonds FI = chloroplasts (as starch granules) tubers, storage organs F = energy store in plants
how is a dipeptide formed
a covalent bond is formed between two amino acids, removing the OH from the amine group and the H from the carboxyl group during the condensation reaction. the reaction is catalysed by peptidyl transferase
name the 5 cations we need to know
Ca2+ calcium ions
K+ potassium ions
Na+ sodium ions
H+ hydrogen ions
NH4+ ammonium ions
list 6 differentiated/specialised cells/tissues in animals
CELLS:
erythrocytes (RBCs
neutrophils (WBCs
sperm cells
muscle cells
TISSUES:
cartilage
epithelial tissues; single or multiple sheets of cells covering internal and external surfaces of organs and lining tubes eg. squamous epithelia, ciliated epithelia
outline the lipids qualitative emulsion test
- Lipids are soluble in alcohol but not water. The emulsion test dissolves any present lipids in ethanol, then adds water, causing the lipid to form a precipitate/emulsion. 2. Ethanol followed by distilled water are added to the samples. A piece of black paper is placed behind the sample to view the precipitate more clearly. 3. Mash the sample, allow solid to settle at the bottom of the tube, pipette the ethanol into a new test tube, add distilled water, use black paper.
what is the cytoskeleton made of and what is its function
it gives strength, shape, support and movement within the cell. It is made of intercellular proteins: microfilaments, intermediate filaments and microtubules.
what is glucose + galactose
lactose- sugar found naturally in milk
what is the function of collagen
bone, cartilage, connective tissue formation prevents blood from bursting artery walls at high pressures
what are the functions of NO3-, HCO3- and PO43- ions
NO3- nitrate ions nitrogen supply to plants for AA and protein synthesis
HCO3- hydrogen carbonate ions maintenance of blood pH
PO43- phosphate ions cell membrane formation, nucleic acid and ATP formation, bone formation
name the 5 anions that we need to know
Cl- chloride ions
HCO3- hydrogen carbonate ions
OH- hydroxide ions
PO43- phosphate ions
NO3- nitrate ions
what is a cell
the unit of all living organisms
how has the hypothesis for how enzymes function ameliorated
the induced fit hypothesis states that the active site is NOT exactly complementary in shape to the substrate. The substrate induces a change in the shape of the active site so that it can be complementary and the enzyme reverts back to the original shape after the reaction.
name and explain the other 4 roles of water and the biological significance of those roles (DOILTDOW) (HCF) (SST) (AF)
- DENSITY OF ICE LOWER THAN DENSITY OF WATER; below 4’C, the molecules of H2O are further apart and therefore contains fewer molecules than an equal volume of liquid water, in a crystalline structure where each molecules is H-bonded to 6 neighbouring molecules. Therefore the ice floats, creating a barrier for the aquatic environment(insulation). -habitat: aquatic animals resist extreme cold and artic animals have a habitat on the surface -transport medium: density changes circulates nutrients 5. HIGH COHESIVE FORCES transport medium: as water is pulled up through the roots and xylem vessels due to evaporation from the leaves of the plant, the cohesive forces from H-bonds hold the column of water together within the cells. 6. STRONG SURFACE TENSION -habitat: collective strength of H-bonds between water molecules allow organisms to live on the surface eg. the water strider. 7. ADHESIVE FORCES -transport medium: as water is pulled up through the roots and xylem vessels due to evaporation from the leaves of the plant, adhesive forces of water to the cell walls help resist the downward force of gravity.
where are multipotent stem cells found
in adult stem cells eg. in the bone marrow
they are present in the adult body and developing embryo
in the cambium of the plant, to form xylem and phloem
outline the 4 stages of STOMATAL PORES OPENING
- K+ is pumped into guard cells.
- H2O follows in by osmosis
- guard cells become turgid
- cells move outwards and the pore is opened
(reverse occurs when pores closing)
Benedict’s quantitative test: Explain why the transmission of red light increases as the glucose concentration in the sample increases.
more glucose = more Cu2+O precipitate

and therefore less copper sulfate(CuSO4), leading to a lower intensity of blue colouration in the solution, and tf more red light transmitted through the solution.
what is glucose + glucose
what is the function of the disaccharide
maltose
produced from hydrolysis of amylose
found in germinating seeds

what is a hydroxyl group and where are they found, what is their compound name
a hydrogen atom bonded to an oxygen atom, which bonds to the carbon skeleton (—OH) found in all saccharides, and ethanols, (glycerol!) alcohol is the name of their compounds
list 5 differentiated/specialised cells/tissues in plants
CELLS:
root hair cells
leaf cells: palisade and guard cells
TISSUES:
of the transport system: xylem and phloem
describe the first type of electron microscope
transmission electron microscope TEM
tissue/cell is infiltrated with resin, cut into very thin slices- diamond knife
beam of electrons is passed through slice of material
where electrons are absorbed = dark
where electrons come through = white
image has 2D flat appearance
objects can be magnified more than 500,000x
TEM has the highest degree of resolution (no figure needed)

which enzymes catalyse the break down of polypeptides or proteins
PROTEASES- water molecule used to break peptide bonds in a hydrolysis reaction, to reform AAs
which sugar is present in DNA
deoxyribose C5 H10 O4
what is the secondary structure of a protein
the way in which the primary structure of a polypeptide chain folds eg. alpha-helices and beta-pleated sheets (held together by hydrogen-bonds)
reasons why amylopectin and glycogen are well suited to their roles as storage molecules in plants and animals
Both are insoluble, branched and compact.
how do we go from monomers to polymers
synthesis by condensation reaction- removal of H2O, formation of bond- example of anabolism
name where the three types of muscle are located
SKELETAL = muscles, attached to skeleton
CARDIAC = in walls of the heart
SMOOTH = in the walls of internal organs

summarise 5 steps in quantitative Benedict’s test for glucose concentration + give AIM
- AIM: To find out whether a substance is present and at what concentration. Reducing sugars eg. glucose, reduce the Cu2+ in Benedict’s reagent to Cu+ which causes a precipitate to form. One measures the concentration of Cu2+ remaining in solution using a colorimeter to become quantitative.*
1. Serial dilution of glucose eg. 1.00%, 0.50%, 0.25%, 0.13%, 0.06%. Control (Benedict’s reagent + water) Unknown.
2. Add Benedict’s reagent. Boil.
3. Centrifuge to remove suspended particles (Cu2+ precipitate) from solution, which are opaque and would therefore scatter the light creating a false low transmission reading. (not allowing transmission of light through the solution in the colorimeter)
4. Set colorimeter to red light and use distilled water in a cuvette to set 100% transmission.
5. Repeat for samples. Draw calibration curve to find unknown concentration of glucose.
give 5 comparisons of haemoglobin/collagen
- globular/fibrous 2. prosthetic group/no prosthetic group 3. soluble/insoluble 4. four polypeptide chains/three
what is an ion
an atom or molecule which does not have equal proton and electron numbers eg. atom loses and electron, now has a net positive charge.
What is the difference in the location of KREBS CYCLE + OX PHOS in eukaryotes and prokaryotes
In the mitochondria of eukaryotic cells and the cytoplasm of prokaryotic cells.

what is cholesterol and what is its function
A hydrophobic sterol that sits between fatty acid chains within membranes to regulate the fluidity of the phospholipid bilayer to be neither too rigid nor too fluid.
(not too fluid at high temperatures by reducing phospholipid movement, not too rigid at low temperatures by hindering solidification as the phospholipids have less energy and more less)

how do laser scanning confocal microscopes work
a <em>single spot of focused light</em> is moved across a specimen which has been dyed using a fluorescent dye.
Light of a longer wavelenth is emitted and used to produce a magnified image.

what is magnification
the degree to which the size of an image is larger than the object itself
how do light microscopes work
light is shone through the specimen/object to be viewed. Lab microscopes are compound; they have 2 lenses
objective lens and eyepiece lens object is magnified twice
describe the effect of substrate concentration on enzyme rate of reaction
- as substrate concentration increases, there are more successful collisions -tf there are more occupied active sites, and more enzyme-substrate complexes made -rate of reaction increases up to the optimum concentration of substrate, where substrate concentration is no longer the limiting factor
- all active sites are occupied and all enzymes present are working at the maximum rate = VMAX!! -tf increasing substrate concentration will no longer increase the rate of reaction, and the graph will plateau

List the property, structure, type of bond, found in, and function of GLYCOGEN
P = highly insoluble, granular S = polysaccharide, highly branched TOB = a-1,4 glycosidic bonds and a-1,6 glycosidic bonds, intramolecular H-bonds FI = liver and muscle cells F = energy store in animals
what are the 4 bonds and interactions that hold tertiary structure in place
- DISULFIDE BONDS/BRIDGES: two cysteine amino acids found together, a strong double bond is formed between the sulfur atoms in the cysteine AAs (S===S) 2. IONIC BONDS. two oppositely charged R groups +ve and -ve form an ionic bond between them 3. HYDROGEN BONDS. 4. HYDROPHOBIC HYDROPHILIC BONDS. in a water-based environment, a globular protein will orientate itself such that the hydrophobic R groups are contained in the middle of the protein and the hydrophilic R groups are on the edges.
what is a dehydrogenase
an enzyme that removes hydrogen from its substrate (oxidises it). H usually accepted by a co-enzyme to be used in
fructose
naturally found in fruit, sweeter than glucose, glucose is sweeter than galactose
what are the 4 types of human stem cells used in research
- embryonic stem cells derived from blastocysts (early embryo)
- adult stem cells found in adult tissues eg. bone marrow
- cord blood stem cells (also amniotic foetal stem cells) found in the umbilical cord
- induced pluripotent stem cells which are multipotent or unipotent cells treated to be made pluripotent
give examples of the following roles of water:
- dissolving
- high latent heat of evaporation
- high cohesive forces
DISSOLVING:
PLANTS; Soil with nitrates, cytosol with nutrients in aquatic environments, xylem transports nutrients, phloem carries dissolved sucrose. ANIMALS; water in blood plasma allows transport of hormones, nutrients: glucose, AAs, minerals, vitamins, waste substances: urea, carbon dioxide
HIGH LATENT HEAT OF EVAPORATION: sweating, panting, evaporation from the mucus membranes, transpiration
HIGH COHESIVE FORCES: xylem

what is resolution
the degree to which it is possible to distinguish/separate between two objects close together
expressed as a measurement
HIGHER RESOLUTION = MORE DETAIL SEEN
what are unipotent cells
cells that can produce only one cell type, but have the property of self-renewal (which distinguishes them from non-stem cells) eg. mother cells of gametes

what is an ionic bond
where one atom donates an electron to the other, forming pos+ and neg- ions held together by attraction of opposite charges
List the property, structure, type of bond, found in, and function of CELLULOSE
P = insoluble, water-permeable, fibrous S = polysaccharide, linear molecules parallel to each other TOB = B-1,4 glycosidic bonds, intermolecular H-bonds FI = plant cell walls F = structural, give strength to cell walls
compare the light and electron microscopes
7+3 possible comparisons
- ADV. LIGHT cheap to purchase vs. expensive to purchase*
- ADV. LIGHT natural colour can be observed vs. black and white*
- ADV. LIGHT material rarely distorted by prep. vs. may distort it and artefacts*
- ADV. LIGHT prep. is relatively quick, simple, cheap vs. requiring expertise, lengthy, complex equipment*
- ADV. LIGHT living material can be viewed vs. only dead due to vacuum*
- ADV. LIGHT small and portable vs. operated in special rooms*
- ADV. LIGHT unaffected by magnetic fields*
1. ADV. ELECTRON possible to see greater depth of field - SEM 3D images vs. restricted depth
2. ADV. ELECTRON can resolve objects <1nm or closer apart (constantly improving) vs. 0.2µm apart
3. ADV. ELECTRON magnifies objects up to and beyond 500,000x vs. up to 1500x
what is the function of haemoglobin + how does it do this
Transport and carry oxygen in the blood.
The haem group contains an Fe2+ ion, onto which the oxygen molecules can bind.

what are microfilaments made of, and what are their 3 functions
ACTIN (protein) give the cell strength, support and keep the cell’s shape allow cell movement eg. changing the shape of the cell; endo/exo-cytosis
where does one find phosphorus in living things
in a phosphate group, where it is bonded to four oxygen atoms with a negative net charge, represented as PO4(-) it is part of the nucleotide, which is found in DNA, RNA. It is a component of energy-rich molecules such as ATP. Thirdly, it is bound to co-enzymes such as NADP/NADPH. It is the hydrophilic ‘head’ of phospholipids that make up the plasma membrane of cells.
what are the axes for a calibration curve
y axis = % transmission of red light x axis = concentration of glucose
describe the effect of temperature on enzyme rate of reaction
-as temp. increases, enzymes have more kinetic energy -more kinetic energy means there is more movement, increasing the likelihood of successful collisions -more molecules have enough energy to react -more enzyme-substrate complexes are made -more product is formed, increasing the rate of reaction -this increases until the optimum temperature is reached -after this point, all enzymes denature at roughly the same temperature
what are the 2 types of 3D protein
GLOBULAR AND FIBROUS. Globular protein tend to form spherical structures with hydrophobic R groups in the centre of the protein and hydrophilic R groups at the edges, meaning they are water-soluble. They have metabolic functions eg. enzymes in all organisms, plasma proteins and antibodies in mammals. Fibrous protein tend to form long fibres and mainly consist of repeated sequences of amino acids which are INSOLUBLE in water. They have structural functions eg. collagen in bone and cartilage, keratin in fingernails and hair.
what is the function of cellulose fibres
They form cell walls in plant cells.
give the two things we need to know about blood cells in terms of specialisation
- blood cells are made from multipotent haemopoietic adult stem cells in the bone marrow
- the adult stem cells differentiate into all the different white blood cells LEUCOCYTES, red blood cells ERYTHROCYTES and PLATELETS.
what are the main 7 properties of cellulose
- HIGH TENSILE STRENGTH -strength of covalent glycosidic bonds between the B-glucose monomers, and between the parallel molecules of cellulose there is intramolecular H-bonding, which is collectively strong.
- EXTRA SUPPORT FROM STRUCTURE- cellulose molecules bond in parallel lines by intramolecular H-bonds to form microfibrils. Microfibrils running in different directions make a H-bonded bundle = a macrofibril.
- SUPPORT- there is no cytoskeleton
- ALLOWS DIFFUSION OF WATER INTO CELLS as the cell wall is fully permeable to water and ions
- PREVENT BURSTING when turgid, turgidity gives the cell strength and support
- MACROFIBRILS MIXED dependent on function
- with lipids/cutin for waxy cuticle, suberin in roots and lignin in xylem walls - ANIMALS DO NOT HAVE CELLULASE ENZYME to digest cellulose

List the property, structure, type of bond, found in, and function of GLUCOSE
P = soluble S = monosaccharide TOB = N/A FI = blood, tissue fluid, cells F = transport sugar in animals, ready source of energy
are saturated fatty acids solid or liquid at room temperature
they are solid because the molecules can pack closely together because there are no kinks in the hydrocarbon ‘tail’
what is an amine group and where is it found, what is their compound name
a nitrogen atom bonded to two hydrogen atoms and the carbon skeleton found in amino acids amines is the compound name
what are the 3 functions of microtubules
-allow movement of organelles within the cells -form the spindle in mitosis, allowing movement of chromosomes to opposite poles of the dividing cell -make up cilia, flagella, centrioles, undulipodia
List the property, structure, type of bond, found in, and function of AMYLOSE
P = insoluble, granular S = polysaccharide, single chain, helical TOB = a-1,4 glycosidic bonds only, intramolecular H-bonds FI = chloroplasts (as starch granules) Tubers, storage organs F = energy store in plants
why are starch and glycogen good stores of energy (3 reasons) (long)
- INSOLUBLE IN WATER- significant for animal cells that do not have a cell wall. Therefore water entering the cell would: 1. affect the water potential of the cell and 2. cause osmotic swell and eventual cytolysis. 2. MONOMERS EASILY HYDROLYSED- tf there can be a rapid release of energy, especially if branched like amylopectin and glycogen- the a-glucose monomers are hydrolysed by enzymes. 3. COMPACT- therefore they do not require a large area for storage, especially when branched like amylopectin and glycogen. They are granular i.e. they form dense granules in the cell; Starch forms in chloroplasts and glycogen mainly in the liver and muscle cells.
which monosaccharides are formed when n=6
C6 H12 O6 = hexose. glucose, fructose, galactose. !structural isomers!
describe the second type of electron microscope
specimen is shadowed with a layer of metal and carbon
it is scanned by a fine electron beam, which is reflected from surface of specimen and transmitted to a detector
3D APPEARANCE
objects can be MAGNIFIED 50,000x

which monosaccharides are formed when n=5
C5 H10 O5 = pentose. ribose, deoxyribose(c5h10o5), ribulose (as in ribulose 1-5 bisphosphate)
what is another cause of membrane fluidity and are fluid and viscous membranes more likely to be found in ectotherms and endotherms
unsaturated hydrocarbon ‘tails’ of phospholipids cause kinks that prevent the molecules from packing too closely together. Fluid ‘kinky’ membranes are more likely to be found in ectotherms eg. fish in very cold water habitats, because it prevents rigidity. Viscous saturated membranes are more likely found in endotherms because they do not become as fluid and unstable.
which elements and components are nucleic acids composed from, what do they form together
CHONP -a pentose monosaccharide (5C atoms) -a phosphate group (PO4(2-)) an inorganic molecule, acidic, negatively charged -a nitrogenous base, a complex organic molecule with 1 or 2 C rings and N DNA has a negative net charge Nucleotides bond by condensation reactions to form a polynucleotide
what is the difference between stem cells in a developing embryo and an adult organism
DEVELOPING EMBRYO
stem cells are able to differentiate into ALL of the specialised embryonic tissues
ADULT ORGANISM
stem cells act as a repair system for the body, replenishing specialised cells eg. bone marrow forming/replacing blood cells
what are the elements and bond names in the four polymers carbohydrates, nucleic acids, proteins and (triglycerides)
polysaccharides- CHO, GLYCOSIDIC nucleic acids- CHONP, PHOSPHODIESTER proteins- CHONS, PEPTIDE fats/lipids- CHO (+P), ESTER
how are polynucleotides formed
The phosphate group at carbon 5 interacts with the OH group at carbon 3 of the pentose sugar of an adjacent nucleotide, forming a PHOSPHODIESTER bond, leading to a strong covalently-bonded sugar-phosphate backbone
what is a phosphate group and where is it found, what is its compound name
A phosphorus atom bonded to four oxygen atoms. One is double bonded, one bonds to carbon skeleton, two have negative charges.
Found in phospholipids, DNA, RNA, ATP, NADP
Name of compound is organic phosphates

what are polypeptides
polymers made of amino acid monomers/molecules
what happens when two close monosaccharides interact
Form a covalent bond through a condensation reaction. The hydroxyl groups on the 1st and 4th carbons interact, forming a 1,4 glycosidic bond and a water molecule. This is now a disaccharide.
what is the primary structure of a protein
the number and sequence of amino acids that will form the polypeptide chain
how does an enzyme speed up the rate of reaction
it lowers the activation energy required for a reaction, i.e. the energy required for a reaction to commence. THE MINIMUM AMOUNT OF ENERGY REQUIRED FOR A SPECIFIC CHEMICAL REACTION TO OCCUR.
state 5 disadvantages of using a TEM
- sometimes there are artefacts meaning the image is not accurate or is obscured
- large voltage needed and a vacuum
- no colour, not 3D
4.
what is haemoglobin
a water soluble globular protein
energy store in animals, where, and how it compares to amylopectin (+importance)
glycogen, which is mainly stored in animals in the liver and muscle cells. Glycogen is more branched than amylopectin. Less space is required to store it. Glycogen is more compact and allows a quicker release of energy due to more free ends to add to or remove from. Therefore storing and release is faster during respiration. To release the glucose molecules, water is required for hydrolysis. Significance: animals are mobile
what is an ‘inorganic’ molecule
minerals/salts/ions (cations and anions)
where are totipotent stem cells found
they are produced from the fusion of an egg and a sperm into a zygote, which is a totipotent cell
found in the morula, which is multiple totipotent cells
name and explain the 7 main functions of lipids
- SCENT; contained in flowers to attract insects
- SOURCE OF ENERGY; due to long hydrocarbon chains (more reduced) there is twice as much energy per g than carbohydrates or protein; helps animals who are mobile; helps small seeds because seed dispersal becomes easier
- ENERGY STORAGE; for the equivalent amount of energy, fats have half the mass of proteins and carbohydrates
- INSULATION; bad conductor of heat/ reduces heat loss
- BUOYANCY; aquatic animals have large quantities of subcutaneous fat
- PROTECTION; vital organs have ‘padding’, in particular the kidneys, heart
- WATER PROOFING; eg. waxy cuticle on plants and insects
what are electron microscopes? how are they different to light microscopes?
- electron beam is used instead of light
- lenses are magnets
- resolution of objects using an EM is greater than LM, therefore they can resolve objects much smaller than a light microscope
- smaller detail can be seen using an EM than a LM
what is the structure of haemoglobin
three polypeptide chains coiled around each other. Each chain is a coil, with hydrogen bonds between them, giving the structure more strength. (important because collagen is a STRUCTURAL PROTEIN)
what are stem cells (3 things)
undifferentiated primal cells common to all multicellular organisms
they retain the ability to renew themselves via cell division
they can differentiate into a wide range of different cell types, depending on their potency

what is a multicellular organism
a collection of organ systems, which is a collection of organs, which is a collection of several tissues carrying out the same general function, which are collections of the same specialised cells carrying out the same function, which are cells differentiated from stem cells
- eg. in plants*
- transport system making up part of the plant –> vascular bundles make up transport system –> root –> root tissue –> root hair cell*
why are cellulose fibres suited to their function
they are strong and insoluble, therefore the cell does not ‘drown’
why must amino acids not be allowed to build up
in excess they are toxic to the body and cannot be stored. They are excreted from the body by deamination, which occurs in the liver of animals. Amino acids are converted to urea and removed from the body in the urine.
summarise what an enzyme is
a globular biological catalyst protein, that speeds up the rate of a specific reaction and remains unchanged by that specific reaction, allowing it to efficiently speed up many reactions repeatedly.
is there a difference in the need for amino acids by plants and humans
yes. plants make all of the amino acids that they require for protein synthesis, the caveat being that they can acquire nitrates from the soil, which are converted to amine groups, and bonded to the products of photosynthesis. Humans must have proteins in their diet, which are broken down and then synthesised into the necessary proteins. ‘Essential amino acids’ are ones that cannot be formed from digested proteins and must be consumed directly.
what are the types of microscope
OPTICAL MICROSCOPES
light microscope
laser scanning confocal microscope
ELECTRON MICROSCOPES
transmission electron microscope TEM
scanning electron microscope SEM
what is cartilage
it is formed from chondrocytes (cartilage cells) within connective tissue.
The condrocytes produce an extracellular matrix of collagen fibres and elastic fibres.
name and explain the first 3 roles of water and the biological significance of those roles (DPACS) (HSHC) (HLHOE)
- DISSOLVES POLAR AND CHARGED SUBSTANCES -solvent: metabolic reactions can occur -transport medium: blood, xylem, phloem 2. HIGH SPECIFIC HEAT CAPACITY -habitat: stable environment for aquatic animals -thermostability for living cells 3. HIGH LATENT HEAT OF EVAPORATION -temperature regulation/coolant: large quantity of energy via radiation out of body to reduce body temp. especially for endotherms -stable environment for aquatic organisms
how do we go from polymers to monomers
digestion by hydrolysis- addition of H2O, break down of bond- example of catabolism
how can you know whether a fatty acid is saturated or unsaturated
Unsaturated fatty acids contain double bonds between carbon molecules (causing kinks in the hydrocarbon ‘tail’ of the molecule) Saturated molecules are linear, with no double bonds between C atoms. If the number of H is more than twice the number of C, it is saturated. eg. C15H31COOH vs C17H33COOH (Double bonding C atoms removes 2 hydrogen atoms’ spaces)
describe the effect of pH on enzyme rate of reaction
-as pH increases, more successful collisions -more enzyme-substrate complexes are made, producing more product, increasing rate of reaction -this increases until the optimum pH level, around -after this point, the higher pH disrupts the ionic and hydrogen bonds -therefore the active site loses its tertiary structure and the shape is no longer complementary to the substrate -there are fewer enzyme-substrate complexes made, less product produced -the rate of reaction is lowered
what is the tertiary structure of a protein
the final 3D structure of a protein, entailing the shaping of the secondary structure, involving coiling or pleating, often with straight chains of amino acids in between
what is the main use of research stem cells and give an example
medicine, due to the ability of stem cells to differentiate into cells with certain characteristics through cell culture
eg. after damage from burns, stem cells may be grown on biodegradable meshes to produce skin grafts very quickly and without the need to remove skin from another part of the body
name the 7 main functions of lipids
- SCENT 2. SOURCE OF ENERGY 3. ENERGY
what is the quaternary structure of a protein
The structure formed when two or more polypeptide chains (called subunits) join together, sometimes with an inorganic component eg. a haem group in haemoglobin PROSTHETIC GROUP, to form a protein. Subunits are not necessarily identical; enzymes are often two identical subunits, while insulin (hormone) has two different subunits. Bonds/interactions are the same as in tertiary structure, but between protein molecules.
what is an artefact
an artificial component that obscures the clear view of an anatomical structure, often arising from the preparation of the specimen/slide.

What are the similarities and differences between the two forms of starch (plant polysaccharide)
Known collectively as starch, a chemical energy store in plants produced from photosynthesis . Made of alpha-glucose monomers. Amylose is linear. Amylose contains only a-1,4 glycosidic bonds. The angle of the bond causes it to form a helical structure, strengthened by intramolecular H-bonds within the molecule. Therefore it is more compact and a lot less soluble than the glucose molecules used to synthesise it. Amylopectin is branched. Amylopectin contains a-1,4 glycosidic bonds and 1,6 glycosidic bonds between carbon 1 and carbon 6. Both have intramolecular H-bonds to hold helical structure.

where are pluripotent stem cells found
in embryonic stem cells taken from the blastocyst or embryo
List the property, structure, type of bond, found in, and function of SUCROSE
P = soluble S = disaccharide (glucose + fructose) TOB = one a-1,4 glycosidic bond only FI = phloem F = transport sugar in plants
how is a polypeptide formed
when many amino acids bond together by peptide bonds, catalysed by the enzyme peptidyl transferase present in ribosomes, the site of protein synthesis.
what are specialised cells
cells differentiated from stem cells
give _ differences between light microscopes, transmission electron microscopes and scanning electron microscopes
- Light microscopes can resolve objects 0.2µm apart, whereas Electron microscopes have a much higher resolution than LM and LSCM (TEM has the highest)
what are the different types of cellulose (3 marks)
Cellulose can be mixed with:

- lipids/cutin for waxy cuticle*
- suberin in roots*
- lignin spiralled in xylem walls*
which are largest to smallest
Centrioles
Nucleoli
Lysosomes
Mitochondria
Mitochondria 1-4µm
Nucleoli
Lysosomes
Centrioles
which bonds in proteins’ tertiary structure are weak
HYDROPHOBIC interactions- non-polar regions are usually in the middle, having been excluded by the water surrounding them and as hydrophilic amino acids form hydrogen bonds with each other/the surrounding.
IONIC bonds between positively & negatively charged amino acids.
Disulfide bridges are covalent.
what is collagen
compare it to haemoglobin
A fibrous protein, a triple helix- very strong. Found in connective tissue. (quaternary structure = 3 subunits)
Haemoglobin is globular, its quaternary structure is 4 subunits, each one with a-helical secondary structure. Conjugated proteins- each has prosthetic group = haem.
how is a triglyceride formed
The glycerol loses three OH
each fatty acid loses HO
in its place there is an O atom
