Board Like Questions 1999 Dennis Livingston
1. In order to bind to DNA, the primary sequence of the histone proteins contain many residues of:
a. tyrosine and phenylalanine.
b. cysteine and methionine.
c. leucine and isoleucine.
d. glutamate and aspartate.
e. lysine and arginine.
2. The amyloid plaques found in the brain cells of Alzheimer patients contain proteins with conformations composed almost entirely of:
a. alpha helices.
b. beta pleated sheets.
c. random coils.
d. beta turns.
e. leucine zippers.
3. The property of hemoglobin that causes oxygen saturation in the lungs and nearly complete oxygen release in the tissues is:
a. the coopertivity among its four subunits.
b. the avidity with which myoglobin picks up oxygen in the tissues.
c. high concentrations of diphosphoglycerate in the lungs.
d. low concentrations of acid in the tissues.
e. its hyperbolic saturation curve for oxygen.
4. Lactate produced in exercising muscle has the beneficial effect of:
a. being converted back into glucose in the muscle.
b. slowing the release of calcium from the sarcoplasm reticulum.
c. causing an acidic environment that unloads oxygen from hemoglobin.
d. being an anerobic source of energy.
e. being the precursor of creatinine phosphate.
5. Collagen is the most abundant protein in the body. It is composed of:
a. a triple helical structure.
b. a single amino acid chain of alpha helix.
c. a double chain of amino acids in an alpha helix.
d. beta pleated sheet.
e. a repeating sequence of four amino acids.
6. Because the Km of liver hexokinase is higher than brain glucokinase:
a. glucose is converted preferentially to glucose-6-phosphate at lower serum concentrations in brain than in muscle.
b. the Vmax of liver hexokinase has to be higher than the Vmax of brain glucokinase.
c. the Vmax of liver hexokinase has to be the same as the Vmax of brain glucokinase.
d. the Vmax of liver hexokinase has to be less than the Vmax of brain glucokinase.
e. most glycolytic enzymes are missing from the liver.
7. The statins, e.g, mevacor, bind noncovalently to the enzyme HMG-CoA reductase because they mimic the transition state of the enzyme. This means they:
a. are irreversible in their action.
b. compete with the substrate HMG-CoA for binding to the active site.
c. are considered suicide (mechanism based) inhibitors.
d. bind to the allosteric site of the enzyme.
e. make the binding of the substrate appear to be tighter, i.e., appear to make the Km of the enzyme lower.
8. RNA polymerase II:
a. transcribes the genes encoding ribosomal RNA.
b. makes polyA tails.
c. adds 5-guanyl caps.
d. begins at a strat codons.
e. transcribes the beta hemoglobin gene.
9. Stop codons:
a. tell RNA polymerase where to stop.
b. tell DNA polymerase where to stop.
c. effect the release of the protein from the tRNA holding the final amino acid.
d. appear in every exon.
e. are six bases long.
10. The most common mutation found in cystic fibrosis is the removal of a three base pair sequence in an exon of the CFTR gene. This gives rise to a:
a. frameshift mutation.
b. nonsense mutation.
c. inversion mutation.
d. silent mutation.
e. deletion mutation.
11. The hemoglobin genes are expressed only in hemopoetic cells. This is likely the result of the specificity of the:
a. stop codons.
b. start codons.
c. TATAA boxes.
d. enhancer and response elements.
e. splice sites.
12. Replication of the DNA in the chromosomes:
a. begins at transcriptional promoters.
b. occurs throughout the cell division cycle.
c. requires RNA polymerase II.
d. begins at multiple origins of replication.
e. proceeds in one direction along each chromosome.
13. The drug AZT inhibits DNA polymerization by:
a. inhibiting primase.
b. preventing helicase from unwinding the nucleic acid strands.
c. blocking the addition of nucleotides to an AZT terminated primer.
d. intercalating into the template strand.
e. preventing proofreading.
14. AZT is an inhibitor of the enzyme:
a. DNA ligase.
b. DNA helicase.
c. DNA topoisomerase I.
d. DNA topoisomerase II.
e. viral encoded reverse transcriptase.
15. The enzyme peculiar to the liver that permits it to secrete glucose into the serum is:
a. phosphofructokinase-1.
b. fructose-6-phosphatase.
c. glucose-6-phosphatase.
d. glycogen phosphorylase.
e. PEP carboxykinase.
16. The gluconeogenic conversion of lactate or alanine into glucose by the liver requires:
a. phosphoenolpyruvate (PEP) carboxykinase.
b. pyruvate dehydrogenase.
c. pyruvate kinase.
d. acetyl-CoA carboxylase.
e. glycogen synthase.
17. Dietary cholesterol and lipids are brought to tissues by:
a. chylomicrons.
b. LDL.
c. HDL.
d. albumin.
e. transferrin.
18. In the postprandial state:
a. liver phosphofructokinase-1 is inactivated.
b. adipocyte hormone sensitive lipase is activated.
c. liver glycogen phosphorylase is activated.
d. liver glycogen synthase is activated.
e. GLUT 4 (skeletal muscle glucose transporter) is reduced in quantity.
19. Liver phosphofructokinase-1 is activated:
a. by high levels of serum glucagon.
b. by high intracellular concentrations of fructose-2,6-bisphosphate.
c. by high intracellular concentrations of ATP.
d. by high intracellular concentrations of cAMP,
e. during gluconeogenesis.
20. During pregnancy the placenta secretes hormones that increase lipolysis in maternal adipocytes and create maternal resistance to insulin. The net effect is to:
a. prevent hypoglycemia in the mother.
b. increase glycolysis and prevent lipolysis in the mother.
c. increase both glycolysis and lipolysis in the mother.
d. decrease the secretion of glucagon.
e. spare maternal glucose for fetal metabolism.
21. One problem with cirrhosis of the liver is high serum concentrations of:
a. glucose.
b. chylomicrons.
c. urea.
d. ammonia.
e. ketone bodies.
22. The vitamin niacin is needed for the conversion of:
a. alanine into pyruvate.
b. glucose into glucose-6-phosphate.
c. glycerol plus fatty acids into triglycerides.
d. malate into oxaloacetate.
e. acetylCoA plus CO2 into malonylCoA.
23. Trimeric G-proteins:
a. have a receptor protein that passes through the membrane once.
b. phosphorylate adenyl cyclase.
c. are active when bound with GTP.
d. transport hormones into cells.
e. always increase the intracellular level of cAMP.
24. The insulin receptor:
a. binds to DNA.
b. activates adenyl cylase.
c. is an integral membrane protein.
d. transports insulin into the cytoplasm
e. is a phosphatase.
25. The insulin receptor:
a. is a nuclear receptor.
b. is a G protein.
c. possesses tyrosine kinase activity.
d. is inhibited by cholera toxin.
e. has a single amino acid chain.
26. The estrogen receptor:
a. is a tyrosine kinase.
b. binds to a specific sequence of DNA
c. activates adenylate cyclase.
d. activates map kinase.
e. is located in the plasma membrane.
27. Intracellular signalling proteins that interact with the insulin receptor possess:
a. leucine zippers.
b. homeoboxes.
c. helix loop helix motifs
d. SH2 domains.
e. zinc findegers.