複選題

3. Which description is correct?
(A) Glycogen is a homopolysaccharide form of glucose.
(B) The galactose unit of the compound Gal(ẞ1→4) Glc residue is at the reducing end.
(C) Starch is the most abundant polysaccharide in nature.
(D) Gly residues are particularly abundant in a-keratin.
(E) All amino acids in proteins are L-amino acids.

複選題39. Which of the following statements concerning restriction endonucleases is (are) TRUE? (A) They protect bacterial cells from invasion by viruses (bacteriophages). (B) They attack RNA, not DNA. (C) They attack single-stranded sequences only. (D) They can produce "sticky ends". (E) They do not display sequence specificity in their site of attack.

40. When electrical current is applied during a gel electrophoresis procedure, the DNA fragments are separated by (A) electrical charge, positive on one side, negatives on the other. (B) the number of poly-A tails associated with each one. (C) their response to the staining chemicals used during the procedure. (D) the size of the fragments. (E) the enzyme binding activity sites.

1. Which of the following pairs of bonds can rotate within a peptide backbone and the torsion angle of the latter is assigned as psi angle? (A) (B)(C) (D)(E)

2. Which description is correct? (A) Every turn of a-helix is 3.6 Å in length. (B) Hydrogen bond in a-helix formed between residue i and i+3. (C) Heparin is glycosaminoglycan. (D) Collagen is full of a-helix structure and has Gly-X-Pro repeating sequence. (E) Orthologous genes are presumed to have been derived by gene duplication followed by gradual changes in the sequences of both copies.

4. In the following enzyme reaction scheme, what sort of multi-enzyme kinetics are shown? (A) Ordered substrate binding with random product release. (B) Ordered substrate binding with ordered product release. (C) Random substrate binding with ordered product release. (D) Random substrate binding with random product release. (E) Ping-pong mechanism.

5. Adenylyl cyclase catalyzes the synthesis of cAMP, and cAMP hydrolysis is catalyzed by a 5'-phosphodiesterase. If caffeine inhibits 5-phosphodiesterases, drinking a caffeinated beverage would  _____ cAMP levels and _____ glycogen phosphorylase activity. (A) increase; decrease. (B) increase; increase. (C) decrease; decrease. (D) decrease; increase. (E) have no effect on; have no effect on.

6. Which one of the following statements concerning the reaction below is   not   true? NADH + + CH3CHO → + CH3CH2OH (A) This reaction happens during vigorous muscle contraction. (B) Oxidizing half reaction is CH3CHO + → CH3CH2OH. (C) Reduction half reaction is NADH → . (D) CH3CHO can be produced from pyruvate. (E) None of above.

7. Which of the below is   not   required for the oxidative decarboxylation of pyruvate to form acetyl-CoA? (A) NAD+. (B) ATP. (C) Lipoic acid. (D) FAD. (E) CoA-SH.

8. Photosynthetic phosphorylation and oxidative phosphorylation appear to be generally similar processes, both consisting of ATP synthesis coupled to the transfer of electrons along an electron carrier chain. Which of the following is   not   true of both processes? (A) Both contain cytochromes and flavins in their electron carrier chains. (B) Both processes are associated with membranous elements of the cell. (C) Both use oxygen as a terminal electron acceptor. (D) Each represents the major route of ATP synthesis in those cells in which it is found. (E) Protons are pumped from the inside to the outside of both mitochondria and chloroplast membranes.

9. A new compound isolated from mitochondria is claimed to represent a previously unrecognized carrier in the electron transfer chain. It is given the name coenzyme Z. Which line of evidence do you feel is the   least   conclusive in assigning this compound a position in the electron transfer chain? (A) Alternate oxidation and reduction of the mitochondrion-bound coenzyme Z can be readily demonstrated. (B) Removal of coenzyme Z from the mitochondria results in a decreased rate of oxygen consumption. (C) The rate of oxidation and reduction of mitochondrion-bound coenzyme is of the same order of magnitude as the overall rate of electron transfer in mitochondria as measured by oxygen consumption. (D) The reduction potential of Z is between that of two compounds known to participate in the electron transport chain. (E) When added to a mitochondrial suspension, coenzyme Z is taken up very rapidly and specifically by the mitochondria.