102年 - [無官方正解]102 國立嘉義大學_碩士班(乙組)招生考試試題_應用化學系：生物化學#146353

1. To determine the isoelectric point of a protein, first establish that a gel: (A) contains a denaturing detergent that can distribute uniform negative charges over the protein’s surface. (B) exhibits a stable pH gradient when ampholytes become distributed in an electric field. (C) is washed with an antibody specific to the protein of interest. (D) neutralizes all ionic groups on a protein by titrating them with strong bases. (E) relates the unknown protein to a series of protein markers with known molecular weights.

2. Thr and/or Leu residues tend to disrupt an  helix when they occur next to each other in a protein because: (A) an amino acid like Thr is highly hydrophobic. (B) covalent interactions may occur between the Thr side chains. (C) electrostatic repulsion occurs between the Thr side chains. (D) steric hindrance occurs between the bulky Thr side chains. (E) the R group of Thr can form a hydrogen bond.

3. Protein S will fold into its native conformation only when protein Q is also present in the solution. However, protein Q can fold into its native conformation without protein S. Protein Q, therefore, may function as a ____________ for protein S. (A) Ligand (B) molecular chaperone (C) protein precursor (D) structural motif (E) supersecondary structural unit

4. An allosteric interaction between a ligand and a protein is one in which: (A) binding of a molecule to a binding site affects binding of additional molecules to the same site. (B) binding of a molecule to a binding site affects binding properties of another site on the protein. (C) binding of the ligand to the protein is covalent. (D) multiple molecules of the same ligand can bind to the same binding site. (E) two different ligands can bind to the same binding site.

5. The benefit of measuring the initial rate of a reaction V0 is that at the beginning of a reaction: (A) [ES] can be measured accurately. (B) varying [S] has no effect on V0. (C) changes in Km are negligible, so Km can be treated as a constant. (D) V0 = Vmax. (E) changes in [S] are negligible, so [S] can be treated as a constant.

6. In a plot of l/V against 1/[S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the: (A) intercept on the l/[S] axis. (B) Vmax. (C) intercept on the l/V axis. (D) pK of the plot. (E) curvature of the plot.

7. Which of the following monosaccharides is not an aldose? (A) erythrose (B) fructose (C) glucose (D) glyceraldehyde (E) ribose

8. Which of the following is a palindromic sequence? (A) AGGTCC (B) CCTTCC (C) GAATCC (D) GTATCC (E) GGATCC TCCAGG GCAAGG CTTAGG CATAGG CCTAGG

9. In the laboratory, recombinant plasmids are commonly introduced into bacterial cells by: (A) electrophoresis – a gentle low-voltage gradient draws the DNA into the cell. (B) infection with a bacteriophage that carries the plasmid. (C) microinjection. (D) mixing plasmids with an extract of broken cells. (E) transformation – heat shock of the cells incubated with plasmid DNA in the presence of CaCl2.

10. The PCR reaction mixture does not include: (A) all four deoxynucleoside triphosphates. (B) DNA containing the sequence to be amplified. (C) DNA ligase. (D) heat-stable DNA polymerase. (E) oligonucleotide primer(s).

11. Sphingosine is not a component of: (A) sphingomyelin. (B) ceramide. (C) cerebrosides. (D) gangliosides. (E) cardiolipin.

12. An example of a glycerophospholipid that is involved in cell signaling is: (A) arachidonic acid. (B) ceramide. (C) Testosterone. (D) Phosphatidylinositol. (E) vitamin A (retinol).

13. The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is Mr 50,000 and the average lipid is 750.) (A) 50 (B) 100 (C) 200 (D) 10,000 (E) 50,000

14. Protein kinase A (PKA) is: (A) activated by covalent binding of cyclic AMP. (B) affected by cyclic AMP only under unusual circumstances. (C) competitively inhibited by cyclic AMP. (D) allosterically activated by cyclic AMP. (E) noncompetitively inhibited by cyclic AMP.

15. The oxidation of 3 mol of glucose by the pentose phosphate pathway may result in the production of: (A) 2 mol of pentose, 4 mol of NADPH, and 8 mol of CO2. (B) 3 mol of pentose, 4 mol of NADPH, and 3 mol of CO2. (C) 3 mol of pentose, 6 mol of NADPH, and 3 mol of CO2. (D) 4 mol of pentose, 3 mol of NADPH, and 3 mol of CO2. (E) 4 mol of pentose, 6 mol of NADPH, and 6 mol of CO2.

16. In a tissue that metabolizes glucose via the pentose phosphate pathway, C-1 of glucose would be expected to end up principally in: (A) carbon dioxide. (B) glycogen. (C) phosphoglycerate. (D) pyruvate. (E) ribulose 5-phosphate.

17. The reaction of the citric acid cycle that is most similar to the pyruvate dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA is the conversion of: (A) citrate to isocitrate. (B) fumarate to malate. (C) malate to oxaloacetate. (D) succinyl-CoA to succinate. (E) -ketoglutarate to succinyl-CoA.

18. Which of the following statements apply (applies) to the oxidation of fatty acids?
1. The process takes place in the cytosol of mammalian cells.
2. Carbon atoms are removed from the acyl chain one at a time.
3. Before oxidation, fatty acids must be converted to their CoA derivatives.
4. NADP⁺ is the electron acceptor.
5. The products of oxidation can directly enter the citric acid cycle for further oxidation.
(A) 1 and 3 only (B) 1, 2, and 3 (C) 1, 2, and 5 (D) 3 and 5 only (E) 4 only

19. In the nitrogen excretion and the urea cycle, which of the following amino acids are essential for humans? (A) alanine (B) aspartic acid (C) asparagine (D) serine (E) threonine

20. In the reoxidation of QH₂ by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because: (A) cytochrome c is a one-electron acceptor, whereas QH₂ is a two-electron donor. (B) cytochrome c is a two-electron acceptor, whereas QH₂ is a one-electron donor. (C) cytochrome c is water soluble and operates between the inner and outer mitochondrial membranes. (D) heart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH₂ for electron transfer to proceed normally. (E) molecules of cytochrome c must first combine physically before they are catalytically active.

21. During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to: (A) create a pore in the inner mitochondrial membrane. (B) generate the substrates (ADP and Pi) for the ATP synthase. (C) induce a conformational change in the ATP synthase. (D)oxidize NADH to NAD⁺. (E) reduce O₂ to H₂O.

22. 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.

23. Which of these can be synthesized by plants but not by humans? (A) Stearate (18:0) (B) Palmitate (16:0) (C) Phosphatidylcholine (D) Pyruvate (E) Linoleate [18:2(9,12)]

24. One amino acid directly involved in the purine biosynthetic pathway is: (A) alanine. (B) aspartate. (C) glutamate. (D) leucine. (E) tryptophan.

25. The synthesis of purine and pyrimidine nucleotides differ in that: (A) ATP is required in the synthesis of purines but not in the synthesis of pyrimidines. (B) purine biosynthesis starts with the formation of PRPP, whereas pyrimidines incorporate the PRPP near the end of the pathway. (C) purine formation requires a THF derivative, whereas pyrimidine formation does not. (D) pyrimidine biosynthesis is tightly regulated in the cell, whereas purine biosynthesis is not. (E) pyrimidines go through many steps, adding a single carbon or nitrogen each time, whereas the basic skeleton for purines is formed by two main precursors.

26. In base-excision repair, the first enzyme to act is: (A) AP endonuclease. (B) Dam methylase. (C) DNA ligase. (D) DNA glycosylase. (E) DNA polymerase.

27. In homologous genetic recombination, RecA protein is involved in: (A) formation of Holliday intermediates and branch migration. (B) introduction of negative supercoils into the recombination products. (C) nicking the two duplex DNA molecules to initiate the reaction. (D) pairing a DNA strand from one duplex DNA molecule with sequences in another duplex, regardless of complementarity. (E) resolution of the Holliday intermediate.

28. The excision (splicing) of many group I introns requires, in addition to the primary transcript RNA: (A) a cytosine nucleoside or nucleotide and a protein enzyme. (B) a guanine nucleoside or nucleotide (only). (C) a protein enzyme only. (D) a small nuclear RNA and a protein enzyme. (E) ATP, NAD, and a protein enzyme.

29. The signal sequences that direct proteins to the nucleus are: (A) always at the amino terminus of the targeted protein. (B) cleaved after the protein arrives in the nucleus. (C) not located at the ends of the peptide, but in its interior. (D) glycosyl moieties containing mannose 6-phosphate residues. (E) the same as those that direct certain proteins to lysosomes.

30. In the protein synthesis, approximately how many NTPs must be converted to NDPs to incorporate one amino acid into a protein? (A) 0 (B) 1 (C) 2 (D) 4 (E) 8

____(A) is most negatively charged at pH 7?

____(B) will yield DNP-tyrosine when reacted with l-fluoro-2,4-dinitrobenzene and hydrolyzed in acid?

____(C) contains the largest number of nonpolar R groups?

____(D) is most positively charged at pH 7?

____(E) will have the greatest light absorbance at 280 nm?

2. Please provide two possible methods to inhibit the transcription in E. Coli. (10%)

3. What is an Okazaki fragment? What enzyme(s) is (are) required for its formation in E. coli? (10%)

4. Describe and contrast positive regulation and negative regulation of gene expression. (10%)