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BCH 3025 Exam 4 with complete solutions 2024_2025
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BCH 3025 Exam 4 with complete solutions 2024_2025
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BCH 3025 Exam 4 with complete solutions2024/2025
1. Which of the following is not required in the synthesis of fatty acids?
A) Acetyl-CoA
B) Biotin
C) HCO3- (CO2)
D) Malonyl-CoA
E) NADH - ANSWER✓✓-NADH
2. Which of the following is not true of the reaction producing malonyl-CoA
during fatty acid synthesis?
A) It is stimulated by citrate.
B) It requires acyl carrier protein (ACP).
C) It requires CO2 (or bicarbonate).
D) One mole of ATP is converted to ADP + Pi for each malonyl-CoA synthesized.
E) The cofactor is biotin. - ANSWER✓✓-It requires acyl carrier
protein (ACP)
3. If malonyl-CoA is synthesized from 14CO2 and unlabeled acetyl-CoA, and the
labeled malonate is then used for fatty acid synthesis, the final product (fatty
acid) will have radioactive carbon in:
A) every C.
B) every even-numbered C-atom.
C) every odd-numbered C-atom.
D) no part of the molecule.
E) only the omega-carbon atom (farthest carbon from C-1). -
ANSWER✓✓-no part of the molecule
,4. Which one of the following statements best applies to synthesis of fatty acids
in E. coli extracts?
A) Acyl intermediates are thioesters of a low molecular weight protein called acyl
carrier protein.
B) CO2 or HCO3- is essential.
C) Reducing equivalents are provided by NADPH.
D) The ultimate source of all the carbon atoms in the fatty acid product is acetyl-
CoA.
E) All of the above - ANSWER✓✓-All of the above
5. In comparing fatty acid biosynthesis with beta-oxidation of fatty acids, which of
the following statements is incorrect?
A) A thioester derivative of crotonic acid (trans-2-butenoic acid) is an
intermediate in the synthetic path, but not in the degradative path.
B) A thioester derivative of D-beta-hydroxybutyrate is an intermediate in the
synthetic path, not in the degradative path.
C) Fatty acid biosynthesis uses NADPH exclusively, whereas beta-oxidation uses
NAD+ exclusively.
D) Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis
by mitochondrial enzymes.
E) The condensation of two moles of acetyl-CoA in the presence of a
crude extract is more rapid in bicarbonate buffer than in phosphate
buffer at the same pH; the cleavage of acetoacetyl-CoA proceeds
equally well in either buffer. - ANSWER✓✓-Fatty acid biosynthesis
uses NADPH exclusively, whereas beta-oxidation uses NAD+
exclusively.
6. Which of the following is not true of the fatty acid synthase and the fatty acid
beta-oxidation systems?
A) A derivative of the vitamin pantothenic acid is involved.
B) Acyl-CoA derivatives are intermediates.
C) Double bonds are oxidized or reduced by pyridine nucleotide coenzymes.
D) The processes occur in different cellular compartments.
E) The processes occur in the mitochondrial matrix. - ANSWER✓✓-
The processes occur in the mitochondrial matrix.
,7. The rate-limiting step in fatty acid synthesis is: - ANSWER✓✓-the
reaction catalyzed by acetyl-CoA carboxylase.
8. Which of the following is not true of the fatty acid elongation
system of vertebrate cells? - ANSWER✓✓-The immediate precursor
of the added carbons is acetyl-CoA.
9. Which of the following is not true about precursors required for
fatty acid synthesis in animal cells? - ANSWER✓✓-NADPH is
produced in the nucleus by malic enzyme
10. Which of these can be synthesized by plants but not by humans?
- ANSWER✓✓-Linoleate [18:2(delta 9,12)]
11. The enzyme system for adding double bonds to saturated fatty
acids requires all of the following except: - ANSWER✓✓-ATP
12. Which of these statements about eicosanoid synthesis is true? -
ANSWER✓✓-An early step in the path to thromboxanes is blocked by
ibuprofen.
13. The biosynthesis of triacylglycerols from acetate occurs mainly
in: - ANSWER✓✓-humans after ingestion of excess carbohydrate.
14. The synthesis of both glycerophospholipids and triacylglycerols
involves: - ANSWER✓✓-phosphatidic acid.
15. Which of these statements about triacylglycerol synthesis is
correct? - ANSWER✓✓-Insulin stimulates conversion of dietary
carbohydrate into triacylglycerols
16. A strategy that is not employed in the synthesis of
phospholipids is: - ANSWER✓✓-condensation of CDP-diacylglycerol
with alcohol.
17. All glycerol-containing phospholipids are synthesized from: -
ANSWER✓✓-phosphatidic acid.
, 18. In E. coli the synthesis of phosphatidylethanolamine directly
involves: - ANSWER✓✓-serine
19. In the synthesis of phosphatidylcholine from
phosphatidylethanolamine, the methyl group donor is: -
ANSWER✓✓-S-adenosylmethionine (adoMet)
20. Palmitoyl-CoA, , is a direct precursor of: - ANSWER✓✓-
sphingosine
21. CDP-diglyceride is not involved in the biosynthesis of: -
ANSWER✓✓-sphingomyelin
22. Which of the following is true of sphingolipid synthesis? -
ANSWER✓✓-CO2 is produced during the synthesis of ceramide from
palmitate and serine
23. Which of the following is not an intermediate in the synthesis of
lanosterol from acetyl-CoA? - ANSWER✓✓-Malonyl-CoA
24. Cholesterol is synthesized from: - ANSWER✓✓-acetyl-coA
25. A 30-carbon precursor of the steroid nucleus is - ANSWER✓✓-
squalene
26. Which of these statements about cholesterol synthesis is true? -
ANSWER✓✓-Squalene synthesis from farnesyl pyrophosphate results
in the release of two moles of PPi for each mole of squalene formed.
27. Which of the following is derived from a sterol? - ANSWER✓✓-
Bile salts
28. Chylomicrons carry____in the______. - ANSWER✓✓-triacylglycerols;
blood
29. Lipoprotein particles in human blood do not contain: -
ANSWER✓✓-lecithin
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