Principles

Question 1

Describe the four types of protein structure.

Answer 1

I: amino acid chain
II: hydrogen bonds etc
III: R group interactions
IV: Co-operativity between subunits

Question 2

Define the terms endergonic/exergonic and endothermic/exothermic, and catabolism/anabolism.

Answer 2

Exothermic - releases energy
Endothermic - takes in energy
Exergonic - spontaneous
Endergonic - not spontaneous
Catabolism - breakdown, exothermic
Anabolism - buildup (Adding), endothermic

Question 3

Give the Henderson-Hasselbach equation.

Answer 3

pH = pKa + log([A]/[HA])

Question 4

What are the main enzymes of DNA replication? How is DNA typically stored?

Answer 4

Helicase - unzips; Primase - forms primers; DNA Polymerase - adds bases; Ligase - glues fragments; topoisomerase - zips DNA back together.
-ve DNA stored wrapped around +ve histone proteins and chromosomes.

Question 5

Describe the key aspects of the central dogma.

Define degenerate and unambiguous.

Answer 5

TFIID recognizes TATA box 15-20 proteins upstream of beginning site. RNA pol II synthesises RNA. T bases are replaced by U. C-G hairpin and poly U-site cleave new RNA strand. Introns are removed and G cap with poly A tail is added.
mRNA goes through ribosomes (EPA sites) until stop codon binds release factor (not tRNA!!!) causing dissociation.
Degenerate: amino acids have multiple codons.
Unambiguous: each codon codes only one amino acid.

Question 6

Define the terms cofactor, coenzyme, apoenzyme, holoenzyme, and the Michealis constant.

Answer 6

Cofactor - a metallic accessory to an enzyme
Coenzyme - an organic accessory to an enzyme
Holoenzyme - enzyme with cofactor
Apoenzyme - enzyme without cofactor
Michaelis - [S] at which velocity of the reaction is exactly 50%.

Question 7

Considering the Lineweaver-Burke plot, describe the difference between competitive and non-competitive inhibitors.

Answer 7

(X axis = 1/[S], y axis = 1/V; so x-intercept = 1/Km and y-int (c) = 1/Vmax)
Non-inhib and competitive have same Vmax but different Km.
Non-comp has same Km but lower Vmax.

Question 8

Name the rate-limiting enzymes of glycolysis, glycogenesis, glycogenolysis, lipogenesis, lipolysis, and the urea cycle.

Answer 8

PFK, glycogen synthase, glycogen phosphorylase, acetyl-coa carboxylase, HMG-CoA reductase, and carbamoyl phosphate synthase I

Question 9

Name the final electron acceptor of respiration. Name also the quantity of electron transporters and ATP produced by each stage.

Answer 9

Oxygen (forming water). Glycolysis - 2xNADH
Krebs - 8xNADH, 2xFADH2
ATP - between 30-32

Question 10

Define polymorphism and name the main nucleotide and chromosomal mutations.

Answer 10

Polymorphism - a prevalent (>1% population) genetic variant that does not necessarily cause disease.
Bases - nonsense, missense, silent, frameshift
Chromosomal - deletion, duplication (together this is aneuploidy), translocation, inversion

Question 11

Name the five most common chromosomal disorders.

Answer 11

t13 - Patau's
t18 - Edward's
t21 - Down's
45X - Turner's
47XXY - Klinefelter's

Question 12

Which cancers are associated with the oncogenes ABL, c-myc, n-myc, BCL-2, and RAS?

Answer 12

Chronic myeloid leukemia, Burkitt lymphoma, neuroblastoma, follicular lymphoma, pancreatic cancer

Question 13

Name the genetic tests best used for smaller, then larger, genetic defects.

Answer 13

Smaller (bases) - Sanger and NGS (NGS > Sang)

Larger - PCR, aCGH (first line), FISH

Question 14

Name the main side effects of each type of antibiotic.

Answer 14

Sulfonamides - SJS
Penicillin - hypersensitivity
Cephalosporins - c. diff
Glycopeptides and aminoglycosides (both -mycin) - ototoxicity and nephrotoxicity
Tetracyclines - grey staining, phototoxicity, hepatotoxicity. Do not use in < 16 years
Macrolides - P450 inhibition, QT lengthening
Quinolones - C. diff, prolongs QT

Question 15

Name the gram negative and positive cocci and bacilli.

Answer 15

+ve cocci: strep, staph, and enterococci
-ve cocci: Neisseria sp., Moraxella sp.
+ve bacilli: ABCDL (actinomyces, bacillus anthracis, clostridium, diptheria, listeria)
-ve bacilli: everything else!

Question 16

Describe the difference between endo- and exotoxin. Describe the three types of haemolysis and the main strep sp. which cause these.

Answer 16

Endotoxin is LPS released from -ve sp., while exotoxin is released from +ve.
Alpha (partial - green: pneumoniae + viridans sp.)
Beta (complete - yellow: pyogenes + agalactiae)
Gamma (no haemolysis - enterococci)
Think: yellow is further from dark red than green, so is more destruction.

Question 17

Name the two main types of virus activation. Name the two techniques which are most used to discover viral aetiologies.

Answer 17

Lytic pathway and lysogenic pathway (replication vs quiescent).
PCR and electron microscopy (not light; too small)

Question 18

Describe the three types of muscle, and how they work to contract.

Answer 18

Skeletal - striated, many nuclei, voluntary
Smooth - non-striated, one nucleus, non-voluntary
Cardiac - branched, striated, one nucleus
Gap (communicating) junctions allow electrolyte transfer. Actin (covered by tropomyosin, nailed down by troponin) is activated when Ca2+ causes troponin conformational change

Question 19

Name the major event or name change that occurs in embryology at the following times: 0 hrs, 4 days, 5D, 7D, 10D, 16D, 3W, 4W, 7W, 8W.

Answer 19

0H - fertilization
4D - morula
5D - blastocyst (cytotrophoblast and embryoblast)
7D - implantation (usually posterior)
10D - bilaminar disc develops
3W - gastrulation (bi to tri)
4W - neurulation
7W - cloacal and oral membranes rupture
8W - embryo is now considered a foetus

Question 20

State the time after fertilization at which these embryonic events occur:
morula, blastocyst, bilaminar disc formation, gastrulation, neurulation, rupture of cloaca and oropharynx, end of embryonic stage.

Answer 20

4D, 5D, 7D, 10D, 3W, 4W, 7W, 8W.

Question 21

What are the three types of joint? Give examples of each.

Answer 21

Fibrous - skull sutures, teeth gomphoses, interosseous membrane of radius and ulna (syndesmoses)
Cartilaginous - 1ry: rib and sternum. 2ry: intervertebral and pubic symphesis
Synovial - everything else!

Question 22

Name the peritoneal pouches, where ascitic fluid may collect.

Answer 22

Vesicouterine, rectouterine (Douglas), vesicorectal, and hepatorenal (Morrison).

Question 23

Name the twelve cranial nerves and their functions (i.e. are they sensory, motor, or both?).
Which CNs transmit parasympathetic fibres to the body?

Answer 23

Oh oh oh, to touch and feel a girl’s vagina, ah heaven:
olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, (v)estibulcochlear, glossopharyngeal, vagus, accessory, hypoglossal.
Some say money matters but my brother says big brains matter more: SSMMBMBSBBMM.
CNs III, VII, IX, X (1973 - same as warfarin clotting factors +1).

Question 24

Name the neurotransmitters of the ANS and their receptor categories, then give their subcategories with functions.

Answer 24

ACh - nicotinic and muscarinic
NA - cholinergic
M1 (Gq) - gastric acid
M2 (Gi) - cardiac inhib
M3 (Gq) - bronchoconstriction
a1 - vessel smooth muscle
a2 - neuronal
b1 - cardiac excitation
b2 - bronchodilation
b3 - adipose breakdown
Cholinergic is generally Gs

Question 25

Describe how GPCRs work.

Answer 25

Activation splits a, b, and y subunits. a has its GDP replaced with GTP, causing stimulation. This continues regardless of receptor until GTP is broken down to GDP.

Question 26

Describe the mechanisms of apoptosis.

Answer 26

Intrinsic: BAX/BAK + effect, BCL - effect. Increases mitochondrial permeability, releasing caspases.
Extrinsic: two methods, ligand based or CD8 based. Ligand (FAS-L or TNFa) binds to receptor (FAS or TNFaR) activating death domain (TRADD or FADD), initiating caspase cascade. CD8+ cells release perforin, breaking open the cell to allow granzyme B to activate caspases.

Question 27

Name the stages of the cell cycle, the checkpoint locations, and describe the Hayflick limit.

Answer 27

G1, S, G2, M (PMAT). Checkpoints at Gs and metaphase. Controlled by CDKs phosphorylating Rb and E2F.
Hayflick limit - cell can only divide about 50-70 times as telomere (TTAGGG sequence) shortens each time; once gone cell undergoes apoptosis.

Question 28

Name the Weinberg Hallmarks of cancer.

Answer 28

Angiogenesis, invasion/metastasis, sustained growth signals, unlimited replication potential, avoidance of immune system, avoiding death, suppression, and repair systems

Question 29

Name and describe the four pillars of ethics.

Answer 29

Autonomy - patient makes own decision
Beneficience - do good
Non-Maleficience: do no harm
Justice/Equity: fair treatment of all

Question 30

Give the formulae for incidence, prevalence, and mortality.

Answer 30

incidence = new cases/risk
prevalence = cases at specific time/risk
mortality = deaths/risk

Question 31

Regarding basic emergency care, give the 4 P’s, absolute basics of approaching medical care, how to hand over to medical care, and the chain of survival.

Answer 31

Preserve life, prevent injury, promote recovery, and phone for help.
DRSABCDE: Danger (to self/others), Response, Shout for help, Airway, Breathing, Circulation, Disability, and Exposure.
AMPLE: Allergies, Medications, PMHx, Last meal, Events leading up
Chain of survival: early recognition (to prevent cardiac arrest), early CPR (to buy time), early defib (to restart the heart), and post-resus care (to restore QoL).

Question 32

Describe how peptide bonds are formed, and describe zwitterions.

Answer 32

NH3 + COOH -> CONH + H2O
Zwitterions: two or more charged group, sum has 0 charge but multiple titratable groups; therefore can act as a buffer system.

Question 33

Name and describe the stages of mitosis. What is the main event that occurs in meiosis to provide genetic variability?

Answer 33

PMAT: prophase (chromosomes condense and spindle fibres form), metaphase (chromosomes line up at the equator), anaphase (pulled apart into chromatids), telophase (nuclear membranes reform). Cytokinesis then occurs.
Crossing over.

Question 34

Give the 5 I’s (how infection is spread), and describe the chain of infection. Name the five moments of hand hygiene. Give the order of donning/removing PPE.

Answer 34

Inhalation, Ingestion, Innoculation, Infant (from mother), Intercourse
Portal of entry -> susceptible host -> infectious microbe -> reservoir -> portal of exit -> transmission
Before patient contact, before aseptic task, after body fluid exposure risk, after patient contact, after patient surroundings
Apron -> mask -> gloves, gloves -> apron -> mask

Question 35

Give the formulae for volume of distribution, clearance, and half life.

Answer 35

Vd = dose/[drug]
Cl = rate of excretion/[drug]
Half-life = 0.693 x Vd / Cl

Question 36

Describe the two forms of active transport and give examples.

Answer 36

Primary - uses ATP directly to move molecules ‘uphill’ on a gradient. E.g. Na/K ATPase (sodium/pot pump)
Secondary - does NOT use ATP but uses Na+ to ‘power’ another ion through, either symport or antiport. E.g. GLUT5 in colon and H/Na pump in stomach

Question 37

What is human factors? Name the components of the SEIPS system.

Answer 37

Non-technical skills

Persons, tasks, tools, organisation, internal, and external, environments

Question 38

What is vasomotor and venomotor tone? Describe how increasing each will result in increased arterial pressure.

Answer 38

Tonic discharge from sympathetic fibres causes partial constriction of blood vessels.
Increased VASOmotor tone causes increased SVR (therefore MAP = CO x SVR goes up)
Increased VENOmotor tone increases venous return, increasing preload and CO (therefore MAP = CO x SVR increases).

Question 39

Describe how PCR works. How does RT-PCR differ?

Answer 39

Three stages - denaturation, annealing, and extension.
1. Heat strands to 96degC
2. Cool to 55degC and allow primers to form
3. Heat again to 75degC and allow TAQ polymerase to extend the primers.
Each PCR cycle lasts about 10 minutes.
RT-PCR uses reverse transcriptase to synthesise a complementary strand of DNA (cDNA) to single stranded RNA viruses.