28. There are four peptides. Their sequences are:

 Peptide A : STRIKE 

Peptide B : ALLRIGHT

 Peptide C: CALENDAR

 Peptide D： HESSMAN 

The pI value of these four peptides should be
(A) A＞B＞D＞C
(B) C＞A＞B＞D
(C) B＞A＞C>D
(D) B＞A＞D＞C
(E)A＞B＞C＞D

24. Fatty-acid biosynthesis is vital in all biology. Which statement is correct? (A) The formation of malonyl-CoA requires micronutrient such as Mn2+. (B) The fatty-acid chain lengthening occurs either in ribosome or endoplasmic reticulum. (C) Double bonds can be introduced in Golgi body. (D) The carbon source at sites of endoplasmic reticulum is malonyl- ACP. (E) All of the above.

25. What effect would ketone bodies have on blood pH? (A) Neutralize pH (B) Lower pH (D) Fluctuate pH (E) No effect on pH (C) Increase pH

複選題26. The following figure shows the phi and psi angles of the residue X in a protein. (A) Phi angle is +45 degree. (B) Psi angle is –90 degree.(C) Phi angle is +90 degree.  (D) Psi angle is +60 degree. (E) Psi angle is +45 degree.

27. There are three proteins X, Y, and Z in 20 mM Tris (pH 7.0) solution. 1. Protein X is a homoheptamer. Its pI is 9.2. The molecular mass of each subunit of the protein X is 20,000 Da and the subunit's pl is 9.2.  2. Protein Y is a monomeric protein with molecular mass of 93,000 Da and its pl is 4.  3. Protein Z is a homodimer. Its molecular mass is 1 40,000 Da and its pI is 8. Please choose the correct answer? (A) When this mixture is loaded onto a cation exchange column, only protein Y can bind to the column: (B) When this mixture is loaded onto a size exclusion column, Protein Y is last eluted. (C) When this mixture is analyzed by a SDS- PAGE, the lowest band is protein Y. (D) When this mixture is analyzed by a SDS- PAGE, protein X and 'Z cannot be separated. (E) When this mixture is loaded onto a cation exchange column, protein X is the first eluted protein.

29. Because the enzymatic reaction rate is determined by the difference in energy between ES and_________ , the tighter binding of the substrate, the_________ the rate of reaction. (D) EXt; higher (A) S; higher (B) P; lower (C) EX+;lower (E) S; lower

30. In the enzyme catalyzed reaction sequence below, can the E- POA intermediate be predicted and why?(A) Yes, the mechanism is a double-displacement reaction. (B) No, the reaction is order single-displacement. (C) No, the reaction is double-displacement. (D) No, the reaction is random single-displacement. (E) None of the above. E:CrP -E + CiP

31. Which of the following statement regarding enzyme regulation is true? (A) Addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system. (B) Allosteric effectors are always more powerful than covalent modification. (C) Addition of an allosteric activator to a K system changes the plot of V vs. [S] from a sigmoidal curve to a more hyperbolic curve. (D) The T state of an enzyme generally has more activity than the R state. (E) None of the above is true.

32. When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below? (R = 8.315 J/mol‧ K and T = 298 K)? (A) is -1.7 kJhmol. (B)  is +1.7 kJ/mol. (C) is incalculably large and positive. (D)  is incalculably large and negative. (E) is zero.

33. Which of the following statement regarding citric acid cycle is false? (A) Citric acid cycle is amphibolic because it plays a role in both catabolism and anabolism. (B) The immediate electron acceptor for the majority of the oxidative reactions of the citric acid cycle is NAD+. (C) Many intermediates of citric acid cycle are starting points for synthesis of a variety of compounds (D) Animals can use fat or acetate as the carbon source because they can replenish citic acid cycle intermediates by anaplerotic reaction. (E) All of above are false.

34. Which of the following four statements regarding glycolysis and gluconeogenesis is correct?  1. The conversion of 1 mole of frctose 1,6-bisphosphate to 2 mole of pyruvate by the glycolytic pathway results in a net formation of 2 mole of NAD+ and 4 mole of ATP.  2. The step of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involves oxidation of NADH to NAD+.  3.Acetate cannot serve as the starting material for the synthesis of glucose via gluconeogenesis in animals.  4. Pyruvate kinase is used in both glycolysis and gluconeogenesis.  5.The oxidation of 3 mole of glucose by the pentose phosphate pathway may result in the production of 3 mole of pentose, 4 mole of NADPH, and 3 mole of CO2. (A)1 and 2 are correct. (B) 3 and 4 are correct. (C) 3 is correct. (D) 4 is correct. (E) All are correct.