4.The double helix of DNA in the B-form is stabilized by:
(A) covalent bonds between the 3' end of one strand and the 5' end of the other.
(B) hydrogen bonding between the phosphate groups of two side-by-side strands.
(C) hydrogen bonds between the riboses of each strand.
(D) nonspecific base-stacking interaction between two adjacent bases in the same strand.
(E) ribose interactions with the planar base pairs.

(4)真空或密封包裝

1. Protein secondary structures are defined by which of the following interactions? (A) Van der Waals interactions (B) Columbic interactions (C) Hydrophobic interactions (D) Hydrogen bonding (E) None of the above

2. What kind of post-translational modification(s) can take place in a serine residue of a protein? (A) Glycosylation (B) Nitrosylation (C) Lipidation (D) Ubiquitination (E) All the above

3. HELQ enzyme requires for catalysis. When the enzyme lacks  , it would be referred to as the: (A) apoenzyme. (B) substrate. (C) coenzyme. (D) holoenzyme. (E) prosthetic group.

5. Most transduction systems for hormones and sensory stimuli that involve trimeric G proteins have in common all of the following except: (A) cyclic nucleotides. (B) nuclear receptors. (C) receptors that interact with a G protein. (D) receptors with multiple transmembrane segments. (E) self-inactivation.

6. Which of the following is an advantage of using multiple steps in electron transport? (A) By using several steps, the net △G is higher (more energy is released). (B) More energy can be captured to synthesize ATP by using small steps. (C) More heat can be generated by using small steps. (D) Small steps allow for both more heat generation and more ATP synthesis. (E) All of these statements are advantages of using multiple steps.

7. Which of the following statements about phospholipase is correct?  1. Phospholipases are designated A, B, etc, based on the different sites in the molecule where they cleave the phospholipids.  2. Phospholipases break down fats by reducing the double bonds to single bonds.  3. Many snake venoms contain phospholipases, whose enzymatic activities act to prevent blood (A) 1 and 2 are correct. (B) 1 and 3 are correct. (C) 2 and 3 are correct. (D) None of above is correct. (E) All of above are correct. clotting.

8. Which of the following statements about free energy or standard state is correct? 1. Free energy is the energy available to perform work.  2. Free energy changes can be measured at constant temperature and pressure.  3. For biochemical reactions, standard state for [H+] is M (A) 1 and 2 (B) 2 only (D) None of above is correct. (E) All of above are correct. (C) 2 and 3

9. Which statement is correct regarding prostaglandins? (A) Prostaglandins are formed from linolenic acid by oxidation and cyclization. (B) Prostaglandins are impotent mediators of inflammation. (C) NSAIDs inhibit the formation of prostaglandins by targeting prostaglandin-endoperoxide H synthase. (D) Prostaglandins are docosanoids. (E) None of the above.

10. Which statement is correct? (A) The PCSK9 protein is a chaperone that binds to HDL receptors on the cell surface. (B) The PCSK9 protein directs the PCSK9-LDL complex to the ribosome to degrade. (C) The PCSK9 protein's inhibition results in more HDL receptors on the cell surface. (D) The current clinically used PCSK9 inhibitors are monoclonal antibodies. (E) The PCSK9 protein is a vital regulator of circulating HDL receptor levels.