IMMS Flashcards
What does the nucleus contain?
DNA (Chromatin)
Euchromatin- loose coils so more easily expressed
Heterochromatin- tight coils around histone proteins so is repressed
Nucleolus (main function is rRNA synthesis - production of ribosomes)
What is the sER and rER for?
sER- membrane lipid synthesis, protein storage and phase 1 detoxification
rER- has ribosomes for protein synthesis
What are the parts of the golgi apparatus?
- Cis face - receives protein/lipid vesicles
- medial face - adds sugars modify these
- Trans –> packages the modified molecules into vesicles to be exocystosed
Perinuclear hoff - plasma cells golgi (light staining area adjacent to the nucleus)
Lysosomes
Degrades protein and involved in cell autolysis via a low pH of 5 maintained by H+/K+ ATPase
Peroxisome function
Beta oxidation of fatty acids
It produces reactive oxygen species H2O2
Removes hydrogen from lipid/alcohol and xenobiotics
What are the diameters of the different filaments in the cytoskeleton? Briefly mention function
Microtubules - 25nm
- Major protein is tubulin
Function: mitosis, also a component of cilia
Intermediate filaments - 10nm
Function: cell integrity and cell to cell contact
no motor protein
Microfilaments - 5-7 nm
- Major motor protein is myosin
- For cell shape and motility
What is lipofuscin?
Wear and tear pigment which appears orangey brown. Indicates that a cell is old
What are G coupled receptors?
They are receptors on the surface of the plasma membrane which mediate the majority of cellular responses to external stimuli. (cascade of reactions)
What are the 4 cell to cell junctions?
Tight junctions
- Do not allow passage between cells
- Cells are sealed
Adherens
– Binds adjacent actin bundles of cells
Desmosomes
- Adjacent intermediate filaments are joined
Gap junctions
- allow adjacent cell passage of ions
- Key in myocardium contraction as a syncytium.
What are the 3 modes of communication for homeostasis?
Autocrine - a cell signal released from a cell binds to receptors on the same cell
Paracrine - secretion into the ECF and cell signals act on neighbouring (nearby) cell – acetylcholine at neuromuscular junction
Endocrine - secretion into the blood and cell signals act on cells further away. – ADH from the posterior pituitary
What are the difference between the two main types of hormones? Examples of both types
Peptide hormones are made from several amino acids. Steroid hormones made from lipid cholesterol
Peptide hormones- water soluble (move directly in the blood) - ADH, Insulin
Steroid hormones- lipid soluble
(move in transport proteins in the blood) - Oestrogen, testosterone
Peptide hormones - bind to receptors on the cell membrane
Steroid hormones- diffuse through the cell membrane to produce an intracellular response
Thus
Peptide hormones- are fast acting
Steroid hormones- are slow acting
Peptide hormones are pre made and stored
Steroid hormones are not pre made
In a 70kg male, what is the total amount of water in the body?
- water in ICF, ECF, IF, Plasma
Total - 42L
ICF - 28L (fluid inside cells- K+ main intracellular ion)
ECF- 14L (Na+ main extracellular ion)
Interstitial fluid - 11L (fluid outside of the blood vessels)
Plasma - 3L (fluid within the blood)
What is sensible and insensible water loss?
Sensible loss- measurable
–> Pee, vomit
insensible loss- immeasurable
–> Sweat, surgery
Main regulator of water loss is the kidney
What is the RAAS system?
- Helps to maintain blood pressure
Renin-angiotensin-aldosterone system
Activated when there is either a decrease in blood pressure (detected by juxtaglomerular cells in the afferent arteriole) or when there is a decreased concentration of NaCl (detected by macula densa cells of the distal convoluted tubule)
The distal convoluted tubule is actually close to the afferent arteriole
The two things mentioned above causes the release of renin from the juxtaglomerular cells –> renin cleaves angiotensinogen released by the liver to angiotensin 1 –> angiotensin 1 is converted by antiotensin converting enzyme in the lungs to angiotensin 2
Angiotensin 2 has multiple effects
- Activates sympathetic nervous system - vasoconstriction
- It stimulates the secretion of ADH from the posterior pituitary which acts on cells of the collecting ducts and distal convoluted tubule to upregulate aquaporins to increase the permeability of the collecting duct to water which increases blood pressure
- It stimulates the release of aldosterone from the adrenal cortex–> increases Na+ reabsorption in the ascending limb of the loop of henle, H2O follows the movement of Na+ causing increased ECF and thus blood pressure.
- Stimulates thirst centre
(Take note, excess water can cause oedema)
What is the antagonist of RAAS system.
Atrial natriuretic peptide released from the atrium when blood pressure is high.
It decreases blood pressure by inhibiting actions of angiotensin 2.
Osmolarity definition
The concentration of substance per litre of solution
Osmolality definition
The concentration of substance per kilogram of solution
What is osmotic pressure?
The pressure that has to be applied on a pure solvent to prevent it from passing into a given solution by osmosis.
What is oncotic pressure?
The osmotic pressure induced by albumin on the capillary walls to keep the fluid in.
Hydrostatic pressure definition
The pressure that a fluid in a confined space is exerting
What are the causes and symptoms of hypernatriemia?
- Excess sodium
Causes: dehydration, increased aldosterone, failing kidney
Symptoms: oedema, increased blood pressure
(hyponatriemia caused by excess water and decreased aldosterone)
Causes and symptoms of hyperkalemia
Causes: kidney failure, decresaed aldosterone, alkalosis
Symptoms: nerve and muscle issues due to regulating resting membrane potential
Hypokalemia (diahrrhoea, acidosis, increased aldosterone)
Symptoms: heart problems
Causes and symptoms of hypercalcemia
Causes increased: Increased PTH, increased vitamin D
Symptoms:bone weakness, calcification
Hypocalcemia - decreased PTH and vitamin D, symptoms- muscle spasm
Explain structure of carbohydrates
How much energy is released per gram of carbohydrates?
Monosaccharides may be joined via glycosidic bonds to form disaccharides, oligosaccharides (3-12) and polysaccharides.
Mainly used for energy source in the form of glucose or energy storage (cellulose, glycogen and starch)
4kcal/g
Explain the structure of lipids
What are they mainly used for?
How much energy is released per gram of lipid?
Exist as triglycerides (3 fatty acids and 1 glycerol)
- Hydrophobic. Ester bonds
They are amphipathic - (tail is hydrophobic, head is hydrophilic)
Mainly used for long term energy storage. Also used for protection and waterproofing
9kcal/g
What are nucleotides and nucleosides comprised of? What kind of bonds? Which are purines and pyramidines?
Nucleotide- pentose sugar, phosphate and a base
Purine (A+G) - 2 bonds
Pyramidine (C, T, U) - 3 bonds
Phosphodiester bonds
Nucleoside- pentose sugar and a base
How many naturally occurring amino acids are there? How many are essential?
20
8/9
Structure of amino acids
- peptide bond
O=C-N-H
The variable group (R group) determines the polarity of the amino acid.
What are the structures of proteins?
Primary - The linear sequence of amino acids held together by covalent bonds
Secondary - Formation of either an alpha helix (spiral arrangement) or beta pleated sheets (directionally oriented)
Super secondary - combination of both secondary structures
Tertiary - 3D conformation of a protein. ionic bonds, disulphide bridges
Quaternary - 3D structure of protein composed of multiple subunits. Consists of more than 1 polypeptide chain linked together. (haemoglobin)
What level of proteins are enzymes?
Enzymes are tertiary and quaternary structures(functional globular) - binds via active sites to the substrates
Co-enzymes bind to enzymes to aid their function
What is the structure of haemoglobin?
What is the mutation to cause sickle cell disease? What is the effect on red blood cells?
2 alpha and 2 beta chains
Quaternary structure
Mutation (in DNA NOT RNA) from GAG (glutamic acid) –> GTG (Valine)
This causes the red blood cells to take on a more sickle shape rather than round, thus decreasing the surface area for absorption.
It is also less flexible and more prone to damage.
It protects against malaria
Describe DNA replication
A semi-conservative process because Every double helix consists of 1 new strand and 1 old strand
Takes place in the nucleus
1) Topoisomerase unwinds the supercoil (also relieves strain)
2) DNA helicase separates the double stranded DNA by breaking the hydrogen bonds between base pairs and creates a replication fork
3) Single stranded binding proteins coat the DNA strands after separation to prevent the strands from re-annealing
4) DNA primase synthesises short RNA primers which serve as an initiation point for DNA polymerase
5) DNA polymerase attaches to the 3’ end of the primer (5’ end of the DNA) and synthesises a new strand of DNA in the 5’ to 3’ direction
6) On the leading strand it continuously synthesises the new DNA strand towards the replication fork. On the lagging strand, it builds away from the replication fork and synthesises the DNA strand in pieces called okazaki fragments
7) DNA ligase joins the okazaki fragments together to form a continuous strand by covalently joining the sugar phosphate backbones together.
Describe DNA transcription
Takes place in the nucleus
1) Transcription factors such as the TATA binding protein control the binding of RNA polymerase to the promoter region.
2) RNA polymerase unwinds and separates the DNA strand into the antisense strand and sense strand
3) As RNA polymerase moves along the template strand from the promotor region, free mRNA nucleotides line up next to their complementary bases and an antiparallel strand is formed in the 5’ to 3’ direction
4) This occurs until the termination point of the gene is reached. RNA polymerase is released and the double strand DNA reforms into its helix shape.
5) Post transcription events occur before the mRNA strand leaves the nucleus via the nuclear pore to attach to the 80s ribosome
Name the post transcription events
Capping- adding of a methyl group to the 5’ end of the transcribed RNA to prevent it from degradation
Polyadenylation- adding of a Poly A tail to the 3’ end of the transcript to improve stability and facilitate it export from the nucleus
Splicing- non coding sequences called introns are removed and coding regions called exons are joined together to form a continuous sequence (can be in any order that exons are joined)
Describe DNA translation
1) The small ribosomal subunit binds to the 5’ end of the mRNA and moves along until it reaches the start codon AUG. The complementary tRNA then attaches to the codon via its anticodon.
2) The large ribosomal subunit aligns itself to the tRNA molecules at the P site, forming a complex with the small subunit.
3) A second tRNA molecule pairs with the next codon in the A site. The amino acid in the P site covalently attaches to the amino acid in the A site via a peptide bone.
4) The ribosome complex moves along the mRNA strand in a 5’ to 3’ direction. The amino acid in the P site moves to the E site and is released. The one in the A site moves to the P site.
5) This happens till a stop codon is reached (UGA, UAG, UAA). Here, a release factor is recruited which signals for translation to stop.
The polypeptide chan in released and sent to the golgi apparatus for modification.
Where is DNA found?
Nucleus and mitochondria (only a small amount of maternal DNA)
Describe the interphase
G1- Rapid cell growth, synthesis of new organelles (DNA damage is checked before DNA replication (p53, p21)
S- Synthesis- DNA replication, protein synthesis, centrosome replication
G2- Mitochondria double, chromosomes condense (DNA damage is checked for pre mitosis by glycosylase enzymes)
G0- fully differentiated cells that don’t replicate further
Describe mitosis
Prophase - The nuclear membrane breaks down, chromosomes condense (visible), centrosomes form microtubule spindle fibres and move to opposite poles of the cell
Prometaphase- microtubule spindle fibres invade the nuclear space and attach to the centromere of the chromosome
Metaphase- spindle fibres contract and chromosomes align on the equatorial plate
Anaphase- continued contraction of spindle fibres separates the sister chromatids and pulls them to opposite poles of the cell
Telophase- chromosomes unfold into chromatin (invisible) and the nuclear membrane reforms. Cytokinesis begins.
What is cytokinesis?
Division of the cytoplasm and cell organelles become evenly distributed around each nucleus. 2 genetically identical daughter cells are formed with a nucleus in each and 46 chromosomes.
Describe meiosis
Meiosis 1 - the first meiotic division is a reduction division from diploid to haploid (2n –> n)
Prophase 1 –> crossing over occurs resulting in genetic diversity
Metaphase 1 –> random assortment occurs further resulting in genetic diversity
Meiosis 2 - the second meiotic division separates the sister chromatids and haploid cells are produced. (2 chromatids –> 1 chromatid)
Describe gametogenesis in a male
Begins a puberty and continues after. There is an EVEN distribution of cytoplasm
Spermatogonia –> primary spermatocyte –> (first meiotic division) 2 x secondary spermatocyte –> (second meiotic division) –> 4 x spermatids (immature sperm) –> they differentiate into spermatozoa.
100-200 million sperm per ejaculation
Process takes 60-65 days
Describe gametogenesis in females
Oogenesis begins at birth and is suspended at metaphase 1 till ovulation (puberty).
There is an UNEVEN cytoplasmic division. Meiosis 2 completes at fertilisation
Oogonia –> primary oocyte –> (first meiotic division) secondary oocyte and polar body –> (second meiotic division) –> ootid and 3 polar bodies
What are 2 problems with meiosis?
Non disjunction - failure of the chromosomes to separate in meiosis 1 and sister chromatids to separate in meiosis 2.
Leads to Trisomy 21 –> down syndrome
Monosomy –> Turner’s syndrome where there is only 1X chromosome in females
Gonadal mosaicism –> 1 of the healthy parents has a mutated germ line. Incidence increases with paternal age.
e.g. duchenne muscular dystrophy –> some egg cells may carry the duchenne gene but the mother’s blood cells do not that is why when tested, she appears negative for the gene but can still pass it on.
Definition of polymorphism
Non pathogenic variation at the locus from wild type (normal alleles)
Consanguinity
The reproductive union of 2 relatives
Penetrance
The percentage of people with the expected phenotype from their genotype
Variable expression
Some people with the same genotype may express it differently
Genetic anticipation
In Huntington’s disease
- There is a wider expansion of trinucleotide repeats (CAG trinucleotide) –> causes mutation of HTT gene
Genetic anticipation means the number of repeats get bigger when they are transmitted onto the next generation resulting in earlier symptoms of greater severity
Autozygous
Getting the same mutation (genotype of a kind) from both sides of the family
Hemizygous, homozygous, heterozygous
Homozygous - two idential alleles at 1 locus
Heterozygous- two different alleles at 1 locus
Hemizygous- presence of a single copy of the gene. Males only have 1 x chromosome and 1 Y chromosome (so they would only have a single copy of whatever gene was present on the chromosomes)
Lyonisation
1 female x chromosome is randomly inactivated preventing 2 sets of genes being expressed in men (you want 1x and 1 Y rather than 2 X chromosomes)
Sex limitation. Give an example
Gene defects only affect 1 sex e.g. BRCA gene
Describe X linked diseases
There is no male to male transmission (unlike autosomal dominant)
Female carriers –> pass it on to men
(females don’t really get it as both x genes would have to have the pathogenic variant from each parent which is very rare)
Describe Y linked diseases
Only affects males. From 1 dad to all the sons
What are the stats for cystic fibrosis?
Carrier frequency –> 1/25
Incidence –> 1/2500
Most common autosomal recessive gene affecting (middle aged) white in the UK
F508 gene defect
state some DNA mutation methods
Duplication - a portion of genetic material or chromosome is duplicated resulting in multiple copies of that region
Mis-sense mutation - a single nucleotide change results in a codon that codes for a different amino acid. A) silent mutation - different codon codes for the same amino acid B) can result in a non functional protein
Nonsense mutation - a mutation that produces a stop codon, resulting in an incomplete usually non functional protein
Deletion/Addition mutation - out of frame deletion - base is deleted, shifting the entire reading frame causing catastrophic effects. - in frame deletion - an entire codon is removed, so only 1 amino acid is lost, less catostrophic
DNA damage –> UV light, radiation, chemicals
Expansion of trinucleotide repeats
What are the arms of the chromosome?
Shorter p arm
Longer q arm
Edwards syndrome
Trisomy 18
What are the energy values for 1 gram of carbohydrates, alcohol, protein, fat?
How many grams of alcohol is 1 unit (10ml)?
Carbohydrate - 4kcal/g
Protein - 4kcal/g
Alcohol 7kcal/g
Fat - 9kcal/g
8 grams of alcohol is 1 unit (10ml).
What is the function of ito cells?
They are the fat storing, stellate cells of the liver. They are the main place for vitamin A storage in lipid droplets
Where are fats, carbohydrates and proteins stored?
Fats- adipocytes, ito cells (liver) - triglycerides
Carbohydrates - liver, skeletal muscle - glycogen
Protein- muscle + liver
Glycolysis
Which is the rate limiting enzyme and process?
Glucose → glucose-6-phosphate via Hexokinase (but glucokinase in the liver)— ATP is converted to ADP (hexokinase minor limiting step)
Glucose-6-phosphate → fructose-6-phosphate via Phosphoglucose Isomerase
Fructose-6-phosphate → Fructose 1,6 bisphosphate via Phosphofructokinase-1 (1) – ATP is converted to ADP RATE LIMITING STEP
Fructose 1,6 bisphosphate → split into 2, 3 carbon molecules. Dihydroxyacetone phosphate and glyceraldehyde-3-phosphate via aldolase
Dihydroxyacetone phosphate must converted into glyceraldehyde-3-phosphate via triose-phosphate isomerase to be used in further reactions
Glyceraldehyde-3-phosphate → 1,3- bisphosphoglycerate via glyceraldehyde-3-phosphate dehydrogenase (triose phosphate dehydrogenase) – 2NAD+ → 2 NADH + H+
1,3 bisphosphoglycerate → 3 phosphoglycerate via phosphoglycerate kinase - 2 ADP is converted to 2 ATP (the phosphate is removed to convert ADP to ATP)
3 phosphoglycerate → 2 phosphoglycerate via phosphoglycerate mutase
2 phosphoglycerate → phosphoenolpyruvate via enolase – 2 H2O is removed
Phosphoenolpyruvate → pyruvate via pyruvate kinase - 2 ADP is converted to ATP
Good gracious father franklin did get by picking pickles
Harry Potter’s parents are incredibly good people, pretty even powerful
Net yield for glycolysis
2 Pyruvate, 2 NADH, 2 H+, 2 ATP (2H2O)
What regulates hexokinase?
Minor regulator of glycolysis
Glucose stimulates hexokinase
Glucose-6-phosphate inhibits hexokinase (allosteric inhibition- binds to non catalytic site causing conformational changes)
Insulin increases synthesis of hexokinase, increasing glycolysis
Glucagon inhibits hexokinase, decreasing glycolysis
What regulates PFK-1 (phosphofructokinase - 1)
Major regulator of glycolysis
Main rate limiting step
Phosphofructokinase-1 (PFK-1) - most highly regulated step in glycolysis
ATP allosterically inhibits PFK-1 (too much ATP formation signals to reduce glycolysis)
Acidosis also inhibits it.
AMP is an activator of PFK-1 (When ATP is used up, ADP accumulates and is converted into AMP by adenylate kinase)
Citrate (first product of the kreb’s cycle) allosterically inhibits PFK-1 (Kreb’s cycle is too active)
Fructose -2,6- bisphosphate - generated from fructose 6 phosphate allosterically activates PFK-1 → converts more fructose -6 -phosphate to fructose 1,6 bisphosphate
Insulin stimulates the conversion of fructose 6 phosphate to fructose 2,6 bisphosphate
Glucagon inhibits this
What are the 2 processes in glycolysis that produce ATP?
1,3 bisphosphoglycerate - phosphoglycerate kinase - 3 phosphoglycerate
Phosphoenol pyruvate - pyruvate kinase - pyruvate
What happens to glucose under anaerobic conditions?
Pyruvate is converted into lactate by lactate dehydrogenase
The hydrogen that is added to the pyruvate is derived from NADH + H+ → NAD+
NAD+ produced funnels back to be used in glycolysis to oxidise more glyceraldehyde-3-phosphate (occuring in the cytosol) → if NAD+ is in short supply, glycolysis cant continue
2 lactate + 2ATP + 2H+ (NAD is recycled to be used in glycolysis)
What happens to pyruvate under aerobic conditions?
Pyruvate produces more energy for the cell via decarboxylation and oxidation (removal of H+ picked up by NAD+) forming an acetyl group which combines with coenzyme A to form Acetyl-CoA which can enter the TCA (tricarboxylic acid) cycle for more energy production (in the mitochondrial matrix)
Pyruvate dehydrogenase aids in this process
to produce Acetyl-coA + CO2 + NADH + H+
Krebs cycle
Oxaloacetate + Acetyl coA –> citrate –> isocitrate –> alpha ketoglutarate (NAD+ –> NADH + H+) + CO2 –> succinyl CoA (NAD+ –> NADH + H+) + CO2–> Succinate (GTP–>GDP) –> Fumarate (FAD –> FADH2) –> Malate –> Oxaloacetate (NAD+ –> NADH + H+)
CAN I KEEP SOME SUCCINATE FOR MY OXALOACETATE
Enzymes
Citrate synthase –> aconitase –> isocitrate dehydrogenase –> alpha ketoglutarate dehydrogenase –> succinyl coA synthetase –> succinate dehydrogenase –> fumarase –> malate dehydrogenase
Citrate And Isocitrate Keep Some Substrate For My Oxaloacetate
Take note
Acetyl coA can also be produced from beta oxidation of fatty acids
Alpha ketoglutarate can be formed from the oxidative deamination of glutamate
How is citrate synthase regulated?
Minor krebs rate limiting step
Allosterically inhibited by ATP and NADH
Competitively inhibited by succinyl CoA
Citrate inhibits Citrate synthase
ADP activates it
How is Isocitrate dehydrogenase regulated?
Major krebs rate limiting step
ADP activates it
ATP and NADH inhibits it
How is alpha ketoglutarate dehydrogenase regulated?
Minor krebs cycle rate limiting step
ATP, Succinyl CoA and NADH inhibits alpha ketoglutarate dehydrogenase
Ca2+ stimulates it
What is the aim of glycolysis and the krebs cycle?
Glycolysis - It is used as an emergency energy producing pathway when oxygen is limiting (it produces a small amount of ATP) and it generates precursors for biosynthesis
Krebs cycle- used to produce NADH and FADH2 used in oxidative phosphorylation
Oxidative phosphorylation
1) NADH and FADH2 releases H+ and Electrons.
2) Energy from the electrons in the electron transport chain is used to pump H+ across the mitochondrial membrane.
3) H+ ions return via ATPase channels, triggering molecular rotation and ATP production.
Hydrogen ions join with oxygen to form water.
Oxygen is the terminal electron acceptor.
Beta oxidation
Fatty acids are converted into Acyl adenylate (ATP –> ADP) –> converted into Acyl CoA via acyl CoA synthetase –> shuttled into the mitochondrial matrix via the carnitine shuttle (rate limiting step) –> carnitine shuttle used if fatty acid chain is longer than 12 carbons. –> acetyl coA is then produced after a series of reactions (oxidation, hydrolysis, oxidation, thiolysis).
Ketogenesis
When there is excess acetyl Coa, acetylcoA is converted into ketones such as Acetate, acetoacetate, etc. (inactive storage form)
(the brain can adapt to use ketones for energy)
When acetyl coA is needed again, ketones are converted back to AcetylCoA
What is diabetic ketoacidosis?
Occurs when there is a high concentration of ketones in the blood
(low insulin level very high blood sugar- insulin causes the uptake of glucose into cells to be used for energy, without insulin there is a lack of energy so the body breaks down fat for fuel –> ketogenesis via acetyl CoA )
Calculating pH of the blood equation
Just roughly know
pH = 6.1 + log10[ HCO₃ / (0.03× PaCO₂) ]
pH= pKA + log10 {A-/HA]
Function of haemoglobin
- O2 transport
-CO2 transport to the lungs - Mops up excess H+ as a buffer to prevent conditions from getting too acidic
- Nitric oxide transport around body for vasodilation
pH levels for acidosis and alkalosis
Under 7.35 pH = acidosis
Over 7.45 pH = alkalosis
Take a break you got this
Well done
What are the pH and HCO3/Co2 levels + compensatory mechanisms for metabolic/respiratory acidosis/alkalosis?
ROME - Respiratory opposites, metabolic equal (pH and HCO3 goes in the same direction)
Metabolic acidosis - - pH low, HCO3 low
Compensatory –> deep hyperventilating, Co2 is low
Metabolic alkalosis – pH high, HCO3 high
Compensatory –> hypoventilation, Co2 is high
Respiratory acidosis – pH low, CO2 high
Compensatory –> Increased renal reabsorption of HCO3, high HCO3
Respiratory alkalosis– pH is high, CO2 low
Compensatory –> Increased excretion of HCO3, low HCO3
80% of bicarbonate is reabsorbed in the PCT
Anion gap equation
What is the normal range
[Na+ + K+] - [Cl- + HCO3-]
10-16
Describe reactive oxygen species. What is their function?
They can damage cells and DNA. Very dangerous.
Function- Respiratory burst (immunological defence mechanism)
It is the rapid release of reactive oxygen species, predominantly from neutrophils for pathogen killing.
Factors affecting gene expression
Cytosine methylation - causes transcriptional silencing
Acetylation of the histone tail makes DNA less tightly coiled and increases transcription
Methylation of histone tail makes DNA more tightly coiled and decreases transcription
Light, pH and temperature can also affect gene expression
How many molecules of NADH and FADH2 and ATP are produced from the krebs cycle? Per glucose molecule
6 NADH
2 FADH
2 ATP
What is the total number of molecules of ATP produced per glucose molecule?
36-38
NADH - 3 molecules
FADH2- 2 molecules
What are the rate limiting steps in glycolysis?
Major - PFK-1
Minor- hexokinase, pyruvate kinase
The processes catalysed by hexokinase, PFK-1 and pyruvate kinase
Hexokinase - glucose stimulates, glucose-6-phosphate inhibits
PFK-1 - AMP stimulates it, ATP, fructose -2,6-bisphosphate and citrate inhibits it
Pyruvate kinase -ATP and acetylCoA inhibits it
What are the rate limiting steps of Kreb’s cycle?
Major - isocitrate dehydrogenase
Minor - Citrate synthase, alpha ketoglutarate
Isocitrate dehydrogenase - ATP and NADH inhibits it, ADP activates it
Citrate synthase- ATP and NADH, Citrate and succinyl CoA inhibits it. ADP activates it
Alpha ketoglutarate- ATP, succinyl CoA and NADH inhibits it, calcium activates it
Definition of metabolism
The sum of chemical reactions that take place within each cell of a living organism that provide energy to maintain life.
What type of inheritance is cystic fibrosis?
Autosomal recessive
Name an autosomal dominant disease
Huntington’s disease
Single nucleotide polymorphism
A DNA sequence variation occurring when a single nucleotide (i.e., A, T, C, G) in the genome sequence is altered, with the alteration present in at least 1% of
the population
