114年 - [非官方正解]114 國立清華大學_碩士班考試入學試題_生命科學暨醫學院甲組(生物與醫學科學組)﹕生物化學#132802

1.Which of the following reaction would favor cellular gluconeogenesis in the fasted state?
(A) Acetyl-CoA activates pyruvate carboxylase.
(B) Fructose 2,6-bisphosphateactivates pyruvate kinase.
(C) AMP activates phosphfructokinase 1.
(D) NAD⁺ activates glyceraldehyde 3-phosphate dehydrogenase.
(E) None of the above.

2.Which of the following urine component can be used as a biomarker to monitor DNA turnover? (A) beta-alanine. (B) ammonium ion (C) beta-aminoisobutyrate. (D) cytidine. (E) AMP

3. Which of the following enzyme is not located in mitochondria?
(A) carbamoyl-phosphate synthase 1
(B) voltage-dependent anion channel
(C) carnitine transporter
(D) DNA polymerase gamma
(E) carbamoyl-phosphate synthase 2

4. Which inhibitor can be used to inhibit complex III of electron transport chain in cells?
(A) cyanide
(B) oligomycin
(C) rotenone
(D) malonate
(E) none of the above

5. Which of the following best describes the relationship between glucose and
fructose?
(A) Epimers
(B) Structural isomers
(C) Enantiomers
(D) Diastereomers
(E) Cis-trans isomers

6. What important reducing agent is an important product of the pentose phosphate
pathway?
(A) NADH
(B) NADPH
(C) NADP+
(D) NAD+
(E) DTT

7. Which glycolytic reaction cannot be directly reversed in gluconeogenesis?
(A) glucose converted into glucose-6-phosphate
(B) glucose-6-phosphate converted into fructose-6-phosphate
(C) 3-phosphoglycerate converted into 1,3-bisphosphoglycerate
(D) 1,3-bisphosphoglycerate converted into glyceraldehyde-3-phosphate
(E) phosphoenolpyruvate converted into 2-phosphoglycerate

8. Which of the following is catalyzed by an oxidoreductase in Krebs cycle?
(A) oxaloacetate ＞ citrate
(B) isocitric acid ＞ a-ketoglutaric acid
(C) fumarate ＞ malate
(D) citric acid ＞ isocitric acid
(E) citric acid ＞ cis-aconitate

9. Why is single-stranded RNA (ssRNA) chemically less stable than single-stranded DNA (ssDNA)? (A) ssRNA has a more rigid structure than ssDNA. (B) because Uridine is less stable than thymidine (C) ssDNA is more flexible than sSRNA. (D) SSRNA has stronger base stacking interactions than ssDNA. (E) SSRNA contains an additional hydroxyl group that makes it more reactive.

10. Which amino acid is the most flexible in protein structures?
(A) Alanine
(B) Leucine
(C) Proline
(D) Serine
(E) Glycine

11. Flippases are enzymes that flip:
(A) fatty acids from one site on glycerol to another.
(B) glucose from its alpha- to beta-configuration.
(C) amino acids between different positions within a protein.
(D) cholesterol between different organelles.
(E) phospholipids to the opposite side of a membrane.

12. How many chiral carbons are present in an aldopentose?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5

13. Aminotransferases are enzymes that have all of the following characteristics except: (A) Can make a a-keto acid from an a-amino acid (B) use pyridoxal phosphate as a carrier of amino acid (C) catalyze highly reversible reactions (D) Use ATР (E) Serum levels are used as a clinical measure of tissue damage

14. Pyruvate can be converted to glucose via gluconeogenesis or oxidized to acetyl- CoA. (A) In the conversion of pyruvate to glucose, the first enzyme pyruvate carboxylase is allosterically inhibited by acetyl-CoA. (B) In the conversion of pyruvate to glucose, the first enzyme pyruvate dehydrogenase is allosterically inhibited by acetyl-CoA. (C) Pyruvate is oxidized to acetyl-CoA by pyruvate dehydrogenase complex, which is allosterically inhibited by acetyl-CoА. (D) Pyruvate is oxidized to acetyl-CoA by pyruvate dehydrogenase complex, which is allosterically activated by acetyl-CoA. (E) None of the above.

15. In the citric acid cycle, all of the following enzymes require NAD+ as a
coenzyme except the reaction catalyzed by:
(A) isocitrate dehydrogenase.
(B) malate dehydrogenase.
(C) a-Ketoglutarate dehydrogenase.
(D) succinate dehydrogenase.
(E) none of the above.

16. HMG-CoA reductase is the key regulatory site in cholesterol synthesis. Which of
the following statement about the regulatory mechanisms of HMG-CoA reductase
is TRUE?
(A) HMG-CoA reductase phosphatase can activate HMG-CoA reductase,
(B) A high AMP:ATP ratio leads to activation of HMG-CoA reductase,
(C) Phosphorylation by cAMP-dependent kinase activates HMG-CoA
reductase,
(D) High cholesterol level increases the half-life of HMG-CoA reductase, (E) High cholesterol level increases HMG-CoA reductase gene expression.

17. What is the role of transition-state stabilization in enzyme-catalyzed reactions?
(A) To enhance the thermal stability of the enzyme
(B) To increase the binding affinity of the substrate
(C) To lower the activation energy, thereby increasing the reaction rate
(D) To increase the stability of the product, thereby reducing side reactions
(E) To provide reaction versatility

18. What is the correct order of these events during muscle contraction?
a. Calcium ions are released from the sarcoplasmic reticulum
b. Hydrolysis of ATP and energy release
c. Detachment of myosin from actin
d. Power stroke
e. Opening of switch 1 and switch 2 on myosin head
(A) aebd c (B)ebcad (C) abcde (D)adebc (E)edcba

19.Enzyme A can act on substrate S and substrate T and follows simple MichaelisMenten kinetics. The Michaelis constant Km of enzyme A for substrate S is Km^S =2 mM, and the rate constant k^s is 5X10³ sec¹. For substrate T, KmT = 5 mM, and
k^T is 2.5X10⁴ sec¹. Which substrate exhibits greater catalytic efficiency?(A) S
(B) T
(C) Enzyme A uses S and T with the same catalytic efficiency.
(D) cannot be determined due to insufficient information.
(E) The result would change if the enzyme's conditions or substrate concentrations varied.

20.Hemoglobin exhibits sigmoidal binding kinetics for oxygen. Which of the
following terms describes hemoglobin's ability to enhance oxygen binding after
the first oxygen molecule binds?
(A) Allosteric inhibition
(B) Competitive inhibition
(C) Allosteric activation
(D) Cooperativity
(E) Catalysis

1. Why do polysaccharides have greater structural diversity compared to polypeptides? (8 points)

2. Which two amino acids are completely positively charged at physiological pH? (8 points)

3. Please describe or illustrate the structure (2 points) of ATP synthase and how this machinery links to the chemiosmotic hypothesis (6 points).

4. Please describe how starch is synthesized in plants (4 points) and how this process is regulated by photosynthesis (4 points).

5. How is the organic sulfide assimilated from sulfate? (8 points)

6. Please compare the carbamoyl-phosphate I and II according to their substrate; intracellular locations; involved pathways; regulators. (8 points)

7. How are eukaryotic transcripts processed and delivered to the ribosomes for
translation? (8 points)

8. What is the structure of ribosomes, and how are they assembled? (8 points)

9. Please design a set of oligonucleotide primers (16-mers) of the following short
DNA sequence for PCR amplification (5' -＞ 3'). (8 points)
TGTGGGAGCTGTGATGATGTTTGTAGGCTTCCTGGGGTGCTATGGGGCCATC
CAGGAGGTGGCTGCAGGCATCTGGGGCTTCGTAAACAAAGACCAGATCGC
CAAGGA

10. A 12-kb DNA fragment was digested with restriction enzymes HindIII and Pstl
under the following conditions:
(1) Digestion with HindIII yielded fragments of 3 kb, 4 kb, and 5 kb.
(2) Digestion with PstI yielded fragments of 2 kb, 5 kb, and 5 kb.
(3) Concomitant digestion with both HindIII and PstI yielded fragments of 1 kb, 2kb, 2 kb, 3 kb, and 4 kb.
Using this data, please construct a possible restriction map of the original 12-kb fragment. (8 points)