IMMS Flashcards
What is euchromatin?
Loosely packed chromosomes. Hyper accessible chromatin so genes activatable. It is unmethylated DNA.
What is heterochromatin?
Tightly packed chromosomes. DNA inaccessible to transcription factors. Silent genes.
Exon shuffling allows…
New proteins to be made e.g. in immune system
What does splice site mutation affect?
Accurate intron removal affected
What is non-sense mediated decay?
Pathway which removes mRNA with premature stop codons
Define ALLELIC HETEROGENEITY
Lots of different mutations in one gene e.g. cystic fibrosis
Define Locus Heterogeneity
Mutations in different genes give the same clinical condition e.g. hypertrophic cardiomyopathy
What is Dominant-negative mutations?
Where the protein from the mutant allele interferes with the protein from the normal allele.
E.g. a dimer where one mutant and one normal allele would result in only 25% normal dimers
What is cytoskeleton
Filament proteins supporting structure of cell
What is lipofuscin?
Lipid containing residues in post mitotic cells e.g. in heart, liver, nerve cells
What does cholesterol do in the cell membrane?
Cholesterol provides some rigidity to the free flowing phospholipid bilayer
Some uses of actin in body
1) They maintain the internal structure of cells
2) They are in adherens junctions which joins actin bundles between neighbouring cells
3) Actin - myosin proteins used in muscles for contraction
What are lipid rafts
Areas were there are high cholesterol and more saturated fatty acids than usual in cell membranes.
Types of endocytosis
1) Phagocytosis
2) Pinocytosis
3) Receptor mediated e.g. depressed areas - coated pits
What % of total body weight is water, and the average volume of water in a 70kg male.
60% of Total Body Weight is water
Which is 42L of a 70kg man
What percentage of body weight is Intracellular?
40% (28L)
What percentage of total body water is Extracellular fluid?
35% of total body water
What is the percentage of total body water is intravascular? Give an average volume of plasma in a 70kg male.
7% of total body water
3L in a 70kg man
What is the average volume of interstitial fluid in a 70kg male?
11L
2 components making up extracellular fluid
1) Blood plasma/Intravascular
2) Interstitial
Transcellular (mucus/CSF…)- maybe
Define Osmolality
Measure of the number of the osmoles of solute per kilogram of solvent (Osm/kg)
Define Osmolarity
The number of osmoses of solute per litre of solvent/solution (Osm/L)
Define Osmotic Pressure
Pressure applied to a solution by a pure solvent, required to prevent inward osmosis through a semipermeable membrane.
Define Oncotic Pressure
Form of osmotic pressure exerted by proteins that tend to pull fluid into its solution
Causes of Oedema
Inflammation - leakage, Venous - increased venous end pressure,
Lymphatic blocked,
Hypoalbuminaemic
Qualities and examples of a steroid hormone.
1) Slow acting
2) Synthesised from cholesterol
3) Lipid Soluble
4) Made and released by cell (no storage)
5) Uses transport proteins to move through blood
6) Diffuses through cell membranes
7) Intracellular response
Examples - Testosterone, oestrogen, cortisol
Name the 4 pathways how dietary components are metabolised
1) Storage - anabolic
2) Biosynthetic -anabolic
3) Oxidative - catabolic
4) Waste Disposal - catabolic
Energy values from 4 fuel types
Carbohydrates - 4 kcal/g
Protein - 4 kcal/g
Alcohol - 7 kcal/g
Lipid - 9 kcal/g
In fed state what does pancreas do.
Pancreas releases insulin which causes glucose and phosphate uptake. Increased glycogenesis, decreases glycogenolysis, less lipolysis, less proteolysis.
Vitamin C uses
Collagen synthesis - helps wounds heal, antioxidant, improves iron absorption, keeps immune system healthy
Vitamin B12 uses
Used to regenerate folate and in DNA, protein and fatty acid synthesis. B12 deficiency can cause a type of anaemia
Functions of glycolysis
Provides ATP
Generates precursors for biosynthesis. Intermediates converted to ribose-5-phosphate (nucleotides), serine, glycine, cysteine (amino acids).
Pyruvate to alanine.
Pyruvate substrate for fatty acid synthesis
Glycerol-3-phosphate is backbone of triglycerides
What does fructose-1,6- bisphosphate activate in the liver and RBCs
Pyruvate kinase activated
Name the enzyme producing citrate from oxaloacetate and acetyl-CoA in TCA cycle
citrate synthase
Enzyme producing isocitrate from citrate in citric acid cycle
aconitase
What is the molecule produced after isocitrate in Kreb’s cycle and the enzyme facilitating the reaction.
Isocitrate to alpha- ketogluarate. Enzyme - isocitrate dehydrogenase.
What reaction (substrate and all products) does alpha-ketogluarate dehydrogenase facilitate. TCA cycles
Substrates: alpha- ketogluarate + CoA
Products: Succinyl-CoA, NADH + H+ , Carbon dioxide
How many carbons does an acetyl CoA, citrate, isocitrate, alpha - ketogluarate, succinate and malate have. Citrate cycle
Acetyl-CoA - 2 Citrate - 6 Isocitrate -6 alpha-ketogluarate - 5 Succinate - 4 Malate -4
Enzyme between succinyl-CoA and succinate. What extra substrate/products are there. TCA cycle
Enzyme - Succinyl CoA thiokinase
Substrate- Succinyl-CoA + Pi
Products- Succinate + GTP + CoA
Name enzyme after succinate in TCA cycle and products
Enzyme- Succinate dehydrogenase
Products - Fumarate + FADH2
The enzyme between
1) fumarate and malate
2) malate and oxaloacetate
in Krebs’ cycle
1) fumerase between fumerate and malate
2) Malate dehydrogenase between malate and oxaloacetate (uses water and produces an NADH)
Which coenzyme results in more ATP being formed during oxidative phosphorylation
NADH more than FADH2
Where does glycolysis take place?
Cytosol
Where does link and TCA cycle take place
Mitochondrial matrix
Where does oxidative phosphorylation take place
Inner mitochondrial matrix
What is gluconeogenesis
It is the generation of glucose using non-carbohydrate sources.
Two causes of ketoacidosis
Diabetic and alcoholic (poor diet).
Ketoacidosis occurs when the body is unable to utilise glucose for energy.
Where does ketogenesis occur
Ketogenesis occurs in hepatocytes, but ketone bodies are used extrahepatically
Buffer definition
Solution which resists changes in pH when small quantities of strong acid or base is added.
Name 4 cellular defences against oxygen toxicity
Antioxidant enzymes, cellular compartmentation, antioxidant vitamins, repair
What do antioxidant enzymes do?
Superoxide dismutase - converts superoxide anion to hydrogen peroxide and oxygen
Catalase - hydrogen peroxide to water and oxygen, protects WBC from their own respiratory burst
Glutathione peroxidase - Hydrogen peroxide and lipid peroxide reduction.
3 examples of antioxidant vitamins
Vitamin E, Vitamin C, Carotenoids.
(Vitamin C: hydrophilic, regenerates reduced vitamin E)
(Carotenoids precursor of vitamin A)
(Vit E found in liver, egg yolks and cereals)
What is a morula?
A 16 cell solid ball of cells, with no cavity within it. When a cavity forms it becomes a blastocyst
What is cleavage
It is when the early zygote splits into many cells without growing.
What shape are epiblast and hypoblasts cells
Epiblast - Columnar
Hypoblast - Cuboidal
