IMMS + Flashcards
What is oncotic pressure?
A type of osmotic pressure exerted by proteins, most notably albumin, that tend to pull fluid into their solution.
Define osmotic pressure.
The pressure that must be applied to a solution in order to prevent inward osmosis through a partially permeable membrane.
What is the cis-face of the golgi apparatus?
The face closest to the nucleus. It is the site of protein phosphorylation and receives vesicles from the endoplasmic reticulum.
What does the medial golgi do?
It modifies products by adding sugars - forms complex OLIGOSACCHARIDES by adding sugars to lipids and peptides
What does the trans golgi do?
Site of PROTEOLYSIS - converts peptides into their active forms (proteins) and sorts molecules into vesicles.
What are the functions of a cell membrane?
Insulate the cell (e.g. myelin sheath), compartmentalise cell, semi-permeable membrane allows the cell to absorb nutrients and expel waste, respond to cell signals, connects the cell to its external environment and forms a barrier to it and allows for intercellular adhesions.
What is a vesicle?
A spherical membrane bound organelle that is used to transport and store material.
What four molecules are in cell membranes?
Glycolipids, glycoproteins, cholesterol and integral proteins.
What type of collagen are basement membranes?
Type 4 collagen
What is a mis-sense mutation?
A single nucleotide change that results in a codon that codes for a different amino acid. This may lead to a dysfunctional protein or may have no effect.
How many Kcal/Kg/day is Basal Metabolic Rate?
24 Kcal/Kg/per day
How much energy is stored as triglycerides?
15kg
How much glycogen is stored and where?
350g. 200g in the liver and 150g in the muscle.
What are the three ketone bodies made by ketogenesis?
Acetoacetate, Acetone and beta-hydroxybutyrate
What is ATP and what is it made of?
Adenosine triphosphate. It is made from: 1 adenine, 1 ribose and 3 phosphates.
What are desmosomes?
A type of cell junction complex that attach cells via intermediate filaments.
Other than the Kreb’s cycle and Glycolysis, how can ATP be made?
Electron transport chain, oxidative phosphorylation, substrate level phosphorylation.
What is gonadal mosaicism?
When there are two different cell populations in the gonads. One population of cells in normal and one is mutated. All gametes from the mutated population will be affected.
What are the four phases of the growth cycle?
G1, S, G2 (interphase phase) M (mitotic phase)
At which phase in mitosis do spindles disappear?
Telophase
When does meiosis II occur?
Only after fertilisation
What is meiosis used for and when does it occur?
Used for the production of gametes. In males in begins in puberty and in females, meiosis I occurs after ovulation. and meiosis II occurs only if fertilisation takes place.
What is non-disjunction?
The failure of homologous chromosomes or sister chromatids to separate during cell division e.g. Down’s Syndrome
How is genetic diversity introduced in meiosis?
Prophase 1 - Crossing over of genetic material from non-sister chromatids
Metaphase 1 - random assortment of chromosomes
What is splicing?
The removal of introns (non-coding regions of a gene) from pre-mRNA to form a fully functioning protein
Define lyonisation.
When one of the female x chromosomes becomes inactive in early embryogenesis.
What is the Fenton reaction?
A process that converts hydrogen peroxide (product of mitochondria oxidative respiration) into a hydroxyl free radical.
Fe2+ + H2O2 —-> Fe3+ + OH- + OH.
What is the Haber-Weiss reaction?
A process that generates a hydroxyl free radical from peroxide and superoxide.
H202 + O2+ –(H+)–> H20 + O2 + OH.
What is endocytosis?
An active, specific, receptor mediated process whereby molecules are absorbed/engulfed by a cell through invagination of the cell membrane to form a vacuole.
3 types: phagocytosis (macromolecules enter cell to form phagosomes) pinocytosis (dissolved solutes) and receptor mediated endocytosis.
What is exocytosis?
Occurs when vesicles from the Golgi Apparatus fuse with the plasma membrane to expel waste or secrete enzymes/hormones.
Name the four types of oedema.
- Inflammatory (leakage)
- Venous (increased end pressure)
- Hypoalbuminemia (abnormally high concentrations of albumin)
- Lymphatic (blocked)
What is the electron transport chain?
A process in which NADH and FADH2 (produced during glycolysis, fatty acid/beta-oxidation) are oxidised (lose electrons) thus releasing energy in the form of ATP. The process by which they do this is known as chemiosmotic phosphorylation.
What is the mechanism by which ATP is formed in the electron transport chain?
Chemiosmotic phosphorylation
What is oxidative phosphorylation?
The metabolic pathway in which mitochondria use their structure, enzymes and energy released by the oxidation of nutrients to reform ATP.
What is the anion gap?
The difference when subtracting the concentration of serum anions (Cl-, HCO3-) from the concentration of serum cations (Na+, K+). Potassium concentrations are usually very low so have minimal effect on the gap, thus potassium is not always included in the equation.
AG = [Na+] - ([Cl- + HCO3-]) = 16 meq/lit.
What condition does the anion gap help to diagnose?
Metabolic acidosis
Briefly explain ROS and ROS formation.
Reactive Oxygen Species - chemically reactive molecules that contain oxygen e.g. OH., O2+, H2O2. ROS are formed as a natural part of oxidation/ normal metabolism of oxygen in mitochondria = ENDOGENOUS.
EXOGENOUS = UV light, smoking, inflammation, drugs.
What equation is useful in determining the pH of a solution?
The Henderson-Hasselbalch equation
What 3 molecules make up a nucleotide?
A pentose sugar, a nitrogenous base and a phosphate molecule.
What is the function of rough endoplasmic reticulum?
Protein synthesis
What is the function of smooth endoplasmic reticulum?
Lipid synthesis
What is the function of the Golgi apparatus?
Processes and modifies endoplasmic reticulum products
Define phenotype.
The physical appearance of an individual as a result of the environment and their genetics
Give examples of types 1, 2, 3, 4, 5 collagen.
Type 1: skin, tendons, vasculature, bone, teeth
Type 2: cartilage
Type 3: liver, kidneys, spleen, uterus, reticular fibres
Type 4: basement membranes
Type 5: placenta
What % of total body collagen does type 1 collagen account for?
90%
Name the features of membrane channels.
They have narrow pores, may be voltage or ligand gated, are selective for size and charge, DO NOT USE active transport and usually transport ions.
How much protein do we require per day?
0.1 g/kg body mass
What is the different between anabolic and catabolic reactions?
ANABOLIC - ‘building up’, use energy and synthesise larger molecules into smaller molecules (glycogen synthesis)
CATABOLIC - ‘breaking down’, form energy and convert larger molecules into smaller molecules
You should expect a high glucose content in diabetic ketoacidosis. True or false?
True - glucose is high due to lack of insulin.
What is the rate limiting step of the Kreb’s cycle and what enzyme catalyses this step?
Step 3: when isocitrate is oxidised to form a-ketoglutamate.
Catalysing enzyme: isocitrate dehydrogenase
What is the first step in the Kreb’s cycle?
Acetyl-CoA (2C) joins with oxaloacetate (4C) to form citrate (6C)
Where is NADH produced in the Kreb’s cycle?
Step 3: isocitrate to a-ketoglutarate
Step 4: a-ketoglutarate to succinyl-CoA
Step 8: malate to oxaloacetate
Genetic defects that affect successive generations earlier and more severely is known as…….
Anticipation
What is ketogenesis?
The formation of ketones via fatty acid breakdown. Ketones are used for energy during low fat states.
What is the equation for fatty acid oxidation/beta oxidation?
Fatty acid –> Acynl adenylate –> Acyl-CoA –> Acetyl-CoA
What are the four ways that components are synthesised in the body?
Storage (anabolic)
Biosynthesis (anabolic)
Waste Disposal (catabolic)
Oxidation (catabolic)
How many ATP molecules can be made from one glucose molecule?
1 glucose molecule = 34 ATP
An ATP molecule has two bonds. What are these bonds called?
Phosphoanhydride bonds.
An ATP molecule has two phosphoanhydride bonds. Are these bonds strong or weak?
Relatively weak - more energy is released than energy required to break them.
What is the equation for the ADP-ATP cycle?
ATP + H20 –> ADP + phosphate + H+
When ATP runs out or more energy is required, it will convert to ADP so the energy required to hold together one of the phosphate bonds can be released and available for use by the cell.
What type of hormones are stored in vesicles ready for release, made by amino acids, bind to the cell membrane and act fast?
Peptide hormones
Give examples of peptide hormones.
Insulin, growth hormone, thyroid stimulating hormone
What are the features of steroid hormones?
They are made from cholesterol, they are produced and released when needed (not stored), they bind to blood protein and they are SLOW acting.
Give examples of steroid hormones.
Cholesterol, oestrogen, testosterone
What is the term for transport across a membrane in which molecules move down their concentration gradient e.g. gaseous exchange?
Diffusion
What is facilitated diffusion?
The transport of molecules across a cell membrane through carrier proteins e.g. glucose.
What is required in active transport and why?
ATP and carrier proteins because molecules are having to move across the membrane AGAINST their concentration gradient (low - high pressure). Example: Na+K+ATPase pump.
What are the 3 regulatory hormones?
- Atrial natriuretic peptide
- Aldosterone
- Anti-diuretic hormone
What does anti-diuretic hormone (vasopressin) do and where is it produced?
Produced in the posterior pituitary gland.
It’s primary function is to retain water in the body by increasing aquaporin numbers in the collecting ducts of nephrons and to CONSTRICT blood vessels.
Where is aldosterone produced and what is its function?
Produced by the adrenal CORTEX.
Plays a role in regulating blood pressure, increasing the absorption of ions and water in the DCT and collecting ducts of nephrons. K+ is secreted to preserve Na+ concentration and to increase water retention and blood pressure.
Where is atrial natriuretic peptide stored and what is its function?
It is an amino acid peptide and is stored/released by atrial myocytes in the heart, in response to atrial distension (enlargement from internal pressure). It is a powerful VASODILATOR.
Describe what happens during prophase.
Chromatin condenses to form chromosomes and nuclear membrane begins to break down. Centrosomes separate and start spindle production.
Describe what happens during prometaphase.
Nuclear membrane disappears completely and spindles grow towards the centre of the cell.
Describe what happens during metaphase.
Chromosomes line up at the equator of the cell and spindles attach to the centromeres.
Describe what happens during anaphase.
Spindles pull on the centromeres, causing the chromosomes to split apart. The chromatids move to opposite poles of the cell.
Explain telophase.
Spindles disappear and chromosomes unravel to form chromatin. A nuclear membrane begins to form and a tight ring of microfilaments forms in the centre of the cell.
Explain cytokinesis.
The ring of microfilaments gets progressively tighter and divides the cell in half. Two cells are produced that are genetically identical to the original parent cell (diploid cells).
Give an example of an autosomal recessive condition.
Cystic fibrosis
Give an example of an autosomal dominant condition.
Huntington’s disease
Give an example of an X-linked recessive condition.
Duchenne muscular dystrophy
What is the water distribution in the ECF?
Interstitial fluid: 11L Plasma: 3L
What is the predominant electrolyte in the ICF?
K+
What is the predominant electrolyte(s) in the ECF?
Na+, Cl-, HCO3-
How much water is there in a) the ECF b) the ICF
ECF: 14L ICF: 28L
What % of our body is water?
60%
Name the key features of peptide hormones.
Produced from amino acids, bind to the cell membrane, stored in vesicles ready for release and act fact.
What is the respiratory burst?
When white blood cells use reactive oxygen species in phagocytosis to damage the cell membrane of bacteria or other invading cells.
What is the function of Topoisomerase?
It breaks the double stranded DNA’s sugar-phosphate backbone and facilitates it’s unwinding.
In what direction does DNA polymerase read?
3’ to 5’ (replication reads 5’ to 3’)
Briefly describe transcription.
TOPOISOMERASE breaks the double stranded DNA sugar-phosphate backbone. DNA-HELICASE unwinds the strands which exposes the coding strand. RNA-PRIMASE arranges free floating mRNA molecules according to base-pair rules. Adjacent mRNA nucleotides bind to form a single strand of mRNA via RNA-POLYMERASE. mRNA leaves the nucleus and SPLICING occurs whereby intron (non-coding regions of DNA) are removed from the mRNA and exons combine to form a fully functioning mRNA molecule.
Briefly describe translation.
mRNA attaches to a ribosome. tRNA have exposed anti-codons that are complementary to the codons on the mRNA. As tRNA binds to mRNA the adjacent amino acids form peptide bonds which group to form a polypeptide.
What are the start and end products of transcription and translation and where does each process occur within the cell.
Transcription: DNA –> mRNA and takes place in the nucleus.
Translation: mRNA –> polypeptide (protein chain) and takes place at a ribosome.
What is a start codon?
A nucleotide triplet that is the first codon of mRNA = AUG = METHIONINE
What is a stop codon?
A nucleotide triplet that signals for the termination of translation: UGA, UAG, UAA.
Describe some of the features of codons.
- Most codons specify an amino acid
- Three “stop” codons mark the end of a protein (UAG, UGA, UAA)
- One “start” codon, AUG, marks the beginning of a protein and also encodes the amino acid methionine
What is a peptide bond?
A type of covalent bond linking two amino acids. The carboxyl group of one molecules reacts with the amino group in the other molecule and 1 molecule of H2O is released.
What are primary, secondary, tertiary and quaternary structures?
Primary: the order of amino acids
Secondary: folding of the chain (alpha helixes and beta pleated sheets)
Tertiary: the overall 3D structure of the folds
Quaternary: the interaction of the 3D structure with sub-units.
What are the eight reactants of the TCA cycle?
Citrate, isocitrate, a-ketoglutarate, succinyl-CoA, succinate, fumerate, malate & oxaloacetate.
What are the eight enzymes in the TCA cycle?
Citrate synthase Aconitase Isocitrate-dehydrogenase a-ketoglutarate-dehydrogenase Succinyl-CoA synthase Succinate-dehydrogenase Fumerase Malate-dehydrogenase
Where are carbons lost in the cycle?
a-ketoglutarate (5 carbons)
succinyl-CoA (4 carbons)
Where does the citric acid cycle take place?
In the matrix of the mitochondria
What are the end products of glycolysis?
2 ATP, 2 Pyruvate, 2NADH
What are the end products of oxidative phosphorylation?
28 ATP
What are the end products of the Kreb’s cycle?
2 ATP, 6 NADH (8-2 in the conversion of pyruvate to acetyl-CoA) and 2FADH2
What are the activators and inhibitors of the TCA cycle?
Activators: ADP
Inhibitors: ATP, NADH, succinyl-CoA
What are the start and end products of glycolysis?
Start: glucose End: pyruvate
Where does glycolysis take place?
In the cytosol of the cytoplasm
Where does fatty acid/beta oxidation occur?
Mainly in the matrix of the mitochondria
State the overall aim of fatty acid/beta oxidation.
To produce acetyl-CoA from fatty acids
When is the carnitine shuffle required?
It is required to transport acetyl-CoA through the inner mitochondrial membrane if it is more than 12 carbons long. If it is <12 carbons long it can freely diffuse through it.
What is consanguinity?
The quality of being descended from the same ancestor as another person
What are lysosomes?
Spherical vesicles derived from the golgi apparatus
Contain digestive enzymes and site of breakdown for most molecules (waste disposal system)
What are the layers of the cytoskeleton?
Microfilaments: made from actin and form a mesh (cell cortex) to the inner cell membrane
Intermediate filaments: spread tensile forces
Microtubules: made from tubulin
What are peroxisomes?
A small organelle present in the cytoplasm of many cells, which contains the reducing enzyme catalase and usually some oxidases.
Are peptide hormones hydrophilic or hydrophobic?
Hydrophilic
What is a zygote?
A fertilised egg cell, formed by the fusion of an egg and sperm cell.
What is the main protein compartment of chromatin called?
Histone
What are the four bases in RNA?
Adenine (A), Cytosine (C), Guanine (G), Uracil (U)
What does fatty acid oxidation involve and what does it produce in each round?
Involves the sequential removal of two carbon units and in one round produces: 1 acetyl-CoA, 1 NADH and 1 FADH2
What enzyme in glycolysis is inhibited in acidosis and why?
Phosphofructokinase-1 because it is pH dependent.
In oxidative phosphorylation what enzyme transports protons into the mitochondrial matrix?
ATP-synthase
Name two electron accepting co-enzymes
NAD+ and FAD+
Approximately how many ATP molecules are made from a) NADH and b) FADH2
a) 2.5
b) 1.5
Briefly describe what happens in anaerobic respiration.
NAD is regenerated from NADH. Pyruvate (from glycolysis) forms lactate. This reaction is catalysed by the enzyme lactate dehydrogenase. NAD goes back into glycolysis so that ATP can be produced.
What is Mendel’s second law?
The law of independent assortment. Alleles from one gene will sort into gametes independently of the alleles of another gene.
What is a multifactorial disease?
A disease that is caused by both genetic and environmental factors e.g. diabetes and schizophrenia
Define karyotype.
The number and appearance of chromosomes in the nucleus of a eukaryotic cell
Define penetrance
The number of people with a gene who display the expected phenotype
Define variable expression.
The variation in the clinical features of a genetic disorder between individuals who have the same gene alteration.
Lipids have hydrophilic and hydrophobic parts, what is the term for this?
Amphipathic
What is the role of ATP synthase in oxidative phosphorylation?
It transports H+ across the inner mitochondrial membrane.
In oxidative phosphorylation, what transports H+ out of the mitochondrial matrix?
Cytochrome C oxidase complex
What is a promotor region?
A nucleotide triplet that controls where RNA polymerase can bind to the DNA so that transcription can occur
What are the subunits of haemoglobin?
2 alpha chains, 2 beta chains and four haem groups
Why is sodium doubled in the plasma osmolality equation?
To account for the negatively charged ions.
What is the plasma osmolality equation?
Osmolality = 2 Na + 2 K + Glucose + Urea ( all in mmol/L).
What are Mendel’s 3 Laws?
- Law of Dominance - an organism with alternate forms of a gene will express the form that is dominant.
- Law of Independent Assortment - the alleles of one gene will sort into gametes independently of the alleles of another gene
- Law of Segregation - each inherited trait is defined by a gene pair. Sex cells contain only one gene of the pair - offspring therefore inherit only one genetic allele from each parent that fuse together in fertilisation.
What is the term for non-sex cells i.e. cells which are not gametes?
Autosomes/somatic cells and they are diploid (they have paired chromosomes)
What is the Knudson two hit hypothesis?
The hypothesis that most genes require two mutations to cause a phenotypic change. Knudson released that sporadic cancer required two acquired mutations. Inherited cancer only requires one acquired mutation, as one has been inherited. You are, therefore, much more likely to develop inherited cancer as the chance of acquiring one mutation is greater than the chance of acquiring two.
What is the inactive X chromosome in a female somatic cell, in species in which sex is determined by the presence of the Y cell call?
A Barr-body
What reactant marks the middle point in glycolysis?
Dihydroxyacetone phosphate
What does total body expenditure comprise of?
Internal heat produced, external work produced and energy stored
How does glucose enter cells?
Via facilitated diffusion. The process is regulated by insulin.
Define imprinting.
One one of two alleles is inactive. For most genes we inherit two working copies of the gene (one from the mother and one from the father). However, in imprinted genes we inherit only one working copy of the gene.
What is the difference between LDL and HDL?
Low density lipoproteins = ‘bad cholesterol’, transport fat to artery walls and invade endothelium to be oxidised - increase the risk of atherosclerosis
High density lipoproteins = ‘good cholesterol’ they carry fat away from cells and reduce the risk of atherosclerosis.
What is a glycosidic bond?
A type of covalent bond between a carbohydrate (sugar) molecule and another molecule which may or may not be a carbohydrate.
Define hemizygous.
When an allele is present on only one chromosome
What does homozygous and heterozygous mean?
Homozygous = a person has two copies of the same allele for a gene Heterozygous = a person has two different alleles of a gene
Where is ribosomal ribonucleic acid (rRNA) produced in the cell?
In the nucleolus
How many layers are in mitochondria?
Three.
Outer membrane - site of lipid synthesis and fatty acid metabolism
Inner membrane - site of cellular respiration and the electron transport chain
Matrix - Kreb’s cycle and oxidative phosphorylation.
What is the cytoskeleton of a cell made from?
Filament proteins
Describe the various layers of the cytoskeleton.
Microfilaments (5nm) - made of actin, form a mesh to the inner cell membrane (cell cortex)
Intermediate filaments (10nm) - spread tensile forces
Microtubles (25nm) - made of tubulin
What is the function of tight junctions?
Seals adjacent cells in epithelial sheet to prevent leakage of molecules between the cells.
What is the function of gap junctions?
Connect the cytoplasm of two adjacent cells via protein channels, which allow molecules, ions and electrical signals to pass between them.
What is the function of adherens junctions?
Attach cells by joining the actin cytoskeleton in one cell to the cytoplasmic face of another cell.
What is the difference between exocrine and endocrine systems?
EXOCRINE - refers to a gland that secretes its products (e.g. enzymes) into ducts that lead to the target tissue.
ENDOCRINE - refers to a gland that secretes its products (e.g. hormones) directly into the blood stream.
What is the difference between osmolality and osmolarity?
Osmolality = the number of solutes per kg of fluid Osmolarity = the number of solutes per L of fluid
What is a positive feedback mechanism and what are examples of this?
A mechanism by which the output enhances the original stimulus. Examples: oxytocin in childbirth, coagulation cascade.
What is a negative feedback mechanism and what are examples of this?
A mechanism in which the output inhibits the original stimulus. Almost all homeostatic control mechanisms are negative feedback mechanisms e.g. blood pressure regulation, temperature regulation, glucose regulation, metabolism/thyroid regulation.
What are the four main types of chemical signalling?
Autocrine, endocrine, paracine and signalling by direct contact.
Describe autocrine signalling.
Cell signals to itself, releasing a ligand that binds to receptors on its own surface or to those inside of the cell.
Describe endocrine signalling.
Used when cells need to transmit signals over long distances. Cells secrete products (hormones) into the bloodstream, which caries them to target cells in the body.
Describe paracrine signalling.
When cells communicate over short distances i.e. with their neighbours. Ligands can diffuse through the space between cells. In synapses the ligands are called neurotransmitters.
Describe signalling by direct contact.
Gap junctions are protein channels between the cytoplasm of adjacent cells, allowing ions, enzymes and electrical signals to be passed between them.
What type of epithelia lines the oesophagus, mouth and vagina?
Stratified squamous epithelium
Where would you find simple squamous epithelium?
Alveoli, blood vessels, lining of the heart, lymphatic vessels.
Where would you find stratified cuboidal epithelium?
Sweat glands, salivary glands and mammary glands.
What type of epithelium lines the trachea and much of the respiratory tract?
Pseudo-stratified ciliated columnar epithelium interspersed with goblet cells.
Where would you find simple cuboidal epithelium?
In ducts and secretory portions of small glands.
The male urethra is lined with….
Stratified columnar epithelium.
Where would you find simple columnar epithelium?
Ciliated: bronchi, uterine tubes and uterus
Non-ciliated: digestive tract, bladder, gallbladder and small intestine
What is the general formula for carbohydrates?
Cn(H20)n
Glucose + galactose =
Lactose
Glucose + fructose =
Sucrose
Glucose + glucose =
Maltose
Electrolyte homeostasis: what is the cause(s) of hypernatremia? And what are the risks?
Cause - water deficit (poor intake, diabetes insipidus etc).
Risks - Dehydration.
(High sodium = low H2O which dehydrates the brain).
Electrolyte homeostasis: What is the cause(s) of hyponatremia and what are its risks?
Causes: Excess water due to IV fluids, diuretics.
Risks: Over hydration - headache, confusion.
Electrolyte homeostasis: What is the cause(s) of hyperkalemia and what are its risks?
Causes: renal failure, acidosis, diuretic inhibitors.
Risks: Cardiac arrest.
Electrolyte homeostasis: What is the cause(s) of hypokalemia and what are its risks?
Causes: D+V, alkalosis, diuretics.
Risks: weakness and dysrhythmia.
Electrolyte homeostasis: What is the cause(s) of hypercalcemia and what are its risks?
Causes: hyperparathyroidism, Vit D toxicity, malignancy.
Risks: renal stones and metastatic calcification.
Electrolyte homeostasis: What is the cause(s) of hypocalcemia and what are its risks?
Causes: renal disease, Vit D deficiency, intestinal malabsorption.
Risks: tetany (spasms).
Summarise autosomal dominant inheritance.
- Manifests in the heterozygous state.
- Male to Male transmission is seen.
- Both males and females are affected equally.
- The disease is present in several generations.
- There is a 50% chance of offspring having the disease.
Summarise autosomal recessive inheritance.
- Manifests in the homozygous state.
- The disease is often not seen in every generation.
- 25% chance of offspring having the disease.
- 50% chance of offspring being carriers.
- Healthy siblings have a 2/3 chance of being carriers.
Summarise X-linked inheritance.
Inheritance of a gene mutation on the X chromosome
Mutations on the X chromosome are more often recessive
Only males are affected
Mum is carrier = if pregnant with female (50% chance will be a carrier, if pregnant with male 50% chance they will have the condition
Affected father = all sons will be unaffected, all daughters will be carriers.
Define insensible losses.
Fluid loss that occurs unconsciously and cannot be measured. Examples: sweating, GI losses, menstrual blood, exhaled water vapour.
What are osmoreceptors and where are they?
Sensory receptors in the thirst centre of the hypothalamus that monitor the concentration of solutes (osmolality) of the blood. If osmolality increases the hypothalamus transmits signals that result in a conscious awareness of thirst and send an action potential to the post. pituitary gland to secrete vasopressin.
Summarise the key methods of water intake.
Drink, diet, IV fluid.
In humans, what is gender determined by?
The presence of the Y chromosome rather than the diploidy of the X
Name the reactants in glycolysis.
Glucose → glucose-6-phosphate → fructose-6-phosphate → fructose-1,6-bisphosphate → DHAP → GLAP → 1,3-bisphosphoglycerate → 3-phosphoglycerate → 2-phosphoglycerate → phosphoenolpryruvate → pyruvate
What are the positive regulators of glycolysis.
AMP 7
What are the negative regulators of glycolysis.
H+, ATP, Citrate, hormonal
Define buffer.
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable.
What are common buffers in the human body?
- Bicarbonate (most important - 43%)
- Proteins (51%)
- Haemoglobin (6%)
What is the equation to demonstrate a bicarbonate buffer?
CO2 + H20 ⇌ H2CO3 ⇌ HCO3- + H+
What is an enzyme?
A substance which acts as a catalyst to bring about a specific biochemical reaction.
Some molecules can bind to enzymes at a site other than their active site. What is the name of this other site?
Allosteric site.
What are co-enzymes?
Organic structures that maximise an enzymes active site.
They cannot catalyse a reaction alone.
What are the four bases of DNA.
Adenine, thymine, cytosine and guanine
Where is ATP lost in glycolysis?
Step 1: glucose - glucose-6-phosphate (-1 ATP)
Step 3: fructose-6-phosphate - fructose-1,6 biphosphate (-1 ATP)
Where is ATP generated in glycolysis?
Step 7: 1,3-Biphosphoglycerate - 3-Phosphoglycerate (+ 2 ATP)
Step 10: phosphoenolpyruvate - pyruvate
Where is GTP generated in the Kreb’s cycle?
Step 5: succinyl-CoA to succinate
