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)

37. What method can be used to functionally inactivate a gene without altering its sequence? 1. gene knockout 　 2. RNA interference 　 3. dominant negative mutation 　 4. CRISPR/Cas9 system (A) 1 and 2 are correct. (B) 2 and 3 are correct. (C) 2 and 4 are correct. (D) 1, 2 and 4 are correct. (E) All of above are correct.

38. Next generation sequencing is much more efficient than the Sanger method because: 　 1. It uses an RNA template instead of DNA. 　 2. It uses gel electrophoresis to resolve end-labeled strands of DNA. 　 3. It uses PCR amplification. (A)1 is correct (B) 2 is corrrect (C) 3 is correct (D) 1 and 3 are correct (E) All of above are correct

39. Compare the advantages and limitations of microarrays and Northern blots for analyzing gene expression. Which statement listed below is correct? 　 1. Microarrays allow a more global analysis of gene expression by analyzing thousands 　 2. Microarrays data analysis can reveal groups of known and unknown genes that are regulated in a coordinated fashion. 　 3. Northern blots allow the analysis of only a few genes at a time. 　 4. Northern blot can reveal the presence of multiple mRNAs from one gene locus that may be differentially expressed. The presence of multiple mRNAs could be missed by microarray analysis. (A) 1, 2, 3 are correct. (B) 1, 3, 4 are correct. (C) 2, 3, 4 are correct. (D) 1, 2, 4 are correct. (E) All of above are correct.

40. Which of the following best describes the function of reverse transcriptase? (A) It's involved in viral attachment to a host cell. (B) It uses an RNA template to make a double-stranded DNA. (C) It uses DNA to synthesize an RNA in the 3' to 5' direction. (D) It joins the gene segments that code for antibodies. (E) Its reaction products can be inserted directly into plasmid.

2. Which of the following statements is   false  ? (A) One protein has one conformation but has many configurations. (B) An α-helix can be destabilized by the presence of two Lys residues near the amino terminus of the α-helix. (C) Determining the precise spacing of atoms within a large protein is possible only through the use of x-ray diffraction. (D) Protein domains may retain their correct shape even when separated from the rest of the protein. (E) Proteins are classified within families or superfamilies based on similarities in structure and/or function.

3. RecA 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.

4. Catalytic antibodies, also called _____ are generated against an antigen that is: (A) zymogens； an analog of the product of the reaction. (B) abzymes； the substrate of the reaction. (C) abzymes； an analog of the transition-state intermediate in the reaction. (D) zymogens； an analog of the transition-state intermediate in the reaction. (E) holoenzyme； the substrate of the reaction.

5. In the catalytic triad common to many serine proteases, _ increases the basicity of _____ thus allowing deprotonation of _____ to serve as a nucleophile. (A) Ser, His, Asp. (B) Asp, His, Ser. (C) Ser, His, His. (D) His, Ser, Asp. (E) Cys, His, Ser.

6. Negative cooperativity of Rep helicase from E. coli means that: (A) once it binds ssDNA, binding dsDNA is prohibited. (B) when both subunits are bound to DNA, ATP hydrolysis promotes release of both subunits. (C) ATP hydrolysis promotes DNA binding of both subunits simultaneously. (D) when one subunit binds DNA, the other releases from the DNA. (E) when one subunit binds DNA, the other binds tightly to the DNA.

7. Each of the following vitamins is required for reactions in the oxidation of pyruvate to CO2 and H2O   except  ? (A) biotin. (B) pantothenate. (C) niacin. (D) thiamine. (E) riboflavin.