20. Which compound serves as the methy! group donor for biological methylation reactions?
(A) Methyl acetate
(B) Methy-tetrahydrofolate
(C) S-Adenosylmethionine
(D) Methanesulfonic acid
(E) Methylephedrine

16. If both NADPH and ribose-5-P are needed in the cells which of the following best represents the net reaction of the pentose phosphate pathway? (A) 4 Fruc-6-P +2 glyceraldehyde-3-P →6 ribose-5-P (B) 3 Gluc-6-P +6 NADP+ →6 NADPH + 3 CO2 + 2 Fruc-6-P + 1 glyceraldehyde-3-P + 6 H+ (C) Gluc-6-P + 2 NADP+ +2 H2O → 2 NADPH + CO2 + ribose-5-P +2 H+ (D) Gluc-6-P + 12 NADP+ +6 H2O →12 NADPH +. 6 CO2 + 12 H+ + Pi (E) None of the above.

17. Shuttle vectors have the property that they: (A) contain promoters for the expression of the gene. (B) have origins of replication for two different cell types, usually bacteria and yeast. (C) are capable of incorporating very large DNA fragments. (D) contain more than one antibiotic resistant gene. (E) None of the above.

18. All ypes of aminotransferase (also known as transaminase) rely on which of the following cofactorlcoenzyme? (A) Pyridoxal phosphate (B) FAD (C) NADH (D) Thiamine pyrophosphate (E) Biotin

19. Which two amino acids are important for ammonia assimilation(吸收) by an organism? (B) Glu and Asp (A) Glu and Gln (C) Gln and Asn (D) Lys and Trp (E) Lys and Arg

21. Allopurinol is a drug used to treated chronic gout(痛風) because it inhibits_______.(A) ureate oxidase (B) adenosuccinase (C) adenosine deaminase (D) xanthine oxidase (E) guanine deaminase

22. Carbamoyl phosphate synthetase I deficiency is an autosomal recessive metabolic disorder that causes __________to accumulate in the blood. (A) bicarbonate (B) ammonium (C)ADP (D) phosphate (E) CO2

23. 5-Fluorouracil (5-FU) is used to treat cancers. It is a mechanism-based inhibitor of _________.(A) ribonucleotide reductase (B) thymidylate synthase (C) adenylosuccinate lyase (D) GMP synthetase (E) xanthine oxidase

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.