BCH 3303 Biochemistry Exam 2 Practice Fall 2024 PDF

BCH 3303 BIOCHEMISTRY EXAM 2 Fall, 2024 PRACTICE EXAM Questions 1-6 refer to the following: A) B) C) D) E) none of these 1. Identify thymine. 2. Id...

BCH 3303 BIOCHEMISTRY EXAM 2 Fall, 2024 PRACTICE EXAM Questions 1-6 refer to the following: A) B) C) D) E) none of these 1. Identify thymine. 2. Identify adenine. 3. Identify cytosine. 4. Identify guanine. 5. Which one forms a DNA base pair with guanine? 6. Which base is not found in mRNA? 7. Identify a template-primer. A) B) C) D) E) none of these 8. Which is a property of the DNA double helix? A) antiparallel deoxyribose chains B) triple-stranded C) 5' deoxyribose D) purines base-paired with purines E) none of these 9. Translate the sequence below (assume initiation upstream; reading frame starts with first nucleotide): 5' GCGGGCUCCGCCUGG 3' A) Gly-Ala-Ser-Ala-Trp B) Trp-Ala-Ser-Gly-Ala C) Ala-Gly-Ser-Ala-Trp D) Gly-Pro-Pro-Arg-Ala E) none of these 10. Where is the amino acid attached in tRNA? E) none of these 11. Which property is similar in mRNA and DNA? A) single-stranded B) contains b-glycosides of purines and pyrimidines C) contains 2'-deoxyribose D) contains uracil E) none of these 12. Which type of RNA is the one with the lowest amounts in most cells? A) mRNA B) rRNA C) tRNA D) equal amounts of mRNA, rRNA and tRNA E) none of the these 13. What is the difference in DNA replication mechanisms on the two progeny strands? A) Different polymerases are used on the two strands, and lagging strand is slower. B) 5' to 3' polymerase is used on both strands, so lagging strand is made in short fragments that are joined. C) Leading strand polymerizes more slowly. D) Leading strand has fructose instead of ribose. E) none of these 2 14. Which is an enantiomer pair? I II III A) I B) II and III C) II D) III E) none of these Questions 15-16 refer to the following: A) B) C) D) E) none of these 15. Which is an a anomer? 16. Identify b-D-glucose C) 17. Identify the a-1,6 bond: B) D) E) none of these A) 18. Identify the reducing end: D) A) B) C) E) none of these 19. Which of the following contains a hemiacetal? A) b-D-glucopyranose B) D-glycerealdehyde C) a-D-fructofuranose D) dihydroxyacetone E) none of these 3 20. Identify the pair of epimers: A) b-D-galactose and b-D-mannose B) b-D-galactose and b-D-fructose C) b-D-mannose and b-D-glucose D) cellulose and chitin E) none of these 21. In the structures below, R1 and R2 are hydrocarbon chains each containing 15 carbons and 31 hydrogens. Which is the correct structure for dipalmitoyl phosphatidylcholine? A) B) C) D) E) None of these 22. Which of the following is a glycerophospholipid? A) phosphatidylserine B) triacylglycerol C) cerebroside D) palmitate E) none of these 23. Which is found in phosphatidylcholine but not sphingomyelin? A) ester-linked hydrocarbon chain B) sphingosine C) phosphate D) choline E) none of these 24. Which of the following fatty acids has the fewest double bonds? A) 14:1 B) 18:2 C) 20:4 D) 16:0 E) none of these 25. Three fatty acids with the same number of carbon atoms have different numbers of double bonds. Which has the lowest melting temperature? A) most unsaturated B) most saturated C) fewest oxygens D) all have the same melting temperature E) none of these 26. What is a major biological function of glycerophospholipids? A) sugar storage B) membrane structure C) fatty acid storage D) enzyme prosthetic group E) none of these 27. Which frequently occurs in membranes? A) Cytosolic proteins cross the bilayer to the extracellular region. B) Lipids or proteins move laterally in the plane of the membrane. C) Lipids move from one membrane surface to the opposite surface ("flip-flop"). D) Ions move into the hydrocarbon region of the lipid bilayer. E) none of these 28. Which of these substances has the lowest permeability through lipid bilayers? A) tryptophan B) indole C) Na+ D) sucrose E) none of these 4 29. Identify the integral membrane protein in the figure: C) D) E) none of these A) 30. Which is an integral membrane protein that is mostly b-sheet? A) bacteriorhodopsin B) porin B) C) sphingomyelin D) triacylglycerol E) none of these 31. Identify the secondary active transporter: A) K+-channel B) Ca2+ pump C) prostaglandin H2 synthase D) Na+-glucose symporter E) none of these 32. Why doesn't Na+ enter the K+ channel's selectivity flter? A) The filter is too small to replace the hydration water of Na+ with b-D-glucose, but hydrated Na+ is too lipophilic to enter. B) The filter is too large to replace the hydration water of K+ with protein oxygens, so hydrated Na+ is excluded. C) The filter replaces the hydration water of K+ with lipid oxygens spaced to perfectly fit the size of Na+. D) The protein oxygens in the filter are spaced too far apart to replace the hydration water of Na+, but hydrated Na+ is too large to enter. E) none of these 33. Which of the following is an example of signal termination in a signal transduction pathway? A) cAMP forms B) epinephrine dissociates from the adrenergic receptor C) GDP bound to Ga is exchanged for GTP D) EGF binds to the EGF receptor E) none of these 34. Which of the following is on the extracellular side of a signaling receptor? A) G-protein binding site B) tyrosine kinase C) insulin binding site D) adenylate cyclase active site E) none of these 35. Which kinase is activated after Ga activates phospholipase C? A) cAMP B) protein kinase C C) diacylglycerol D) protein kinase A E) none of these 36. After a 7TM receptor is activated, a heterotrimeric G protein undergoes several changes. Which of the following is one of these changes? A) a subunit exchanges ATP for GTP B) a subunit exchanges GDP for GTP C) d and f subunits dissociate from the G protein p subunit D) G protein cross-phosphorylates tyrosines on adjacent G proteins E) none of these 5 37. Which second messenger is derived from the plasma membrane? A) Ca2+ B) diacylglycerol C) cAMP D) Na+ E) none of these 38. Which protein binds to GDP and GTP in a manner similar to Ga? A) b-adrenergic receptor B) EGF C) Ras D) Janus kinase E) none of these 39. Identify a receptor that has some tyrosines phosphorylated after activation: A) Janus kinase B) phosphatidylinositol C) b-adrenergic receptor D) phospholipase C E) none of these Questions 40-41 refer to the following: A) palmitate B) coenzyme A C) NADH D) ATP E) none of these 40. Which is a phosphoryl carrier? DGo 41. Which is an electron carrier? 42. What is the standard free energy change for the following reaction (use table of phosphate hydrolysis standard free energy changes at the right)? Glucose 1-phosphate + ADP D Glucose + ATP A) +7.5 kcal/mol B) -2.3 kcal/mol C) -12.3 kcal/mol D) +2.3 kcal/mol E) none of these 43. Which metabolic intermediate is major product of the breakdown of fats, polysaccharides, and proteins? A) NAD+ B) acetyl CoA C) pyrophosphate D) glucose E) none of these 44. Which is the most oxidized molecule? A) CO2 B) CH4 C) CH3OH D) H2CO E) all are equally oxidized 45. Which is a mechanism for increasing the activity of a metabolic process? A) feedback inhibition of an enzyme B) feedback activation of an enzyme C) move substrates and enzymes into different subcellular compartments D) decrease the amount of an enzyme E) none of these 6 1 A 2 B 3 D 4 C 5 D 6 A 7 B 8 A 9 C 10 A 11 B 12 A 13 B 14 A 15 C 16 A 17 C 18 D 19 A 20 C 21 B 22 A 23 A 24 D 25 A 26 B 27 B 28 C 29 A 30 B 31 D 32 D 33 B 34 C 35 B 36 B 37 B 38 C 39 A 40 D 41 C 42 D 43 B 44 A 45 B