複選題

17. Which of the following lead(s) to a point mutation?
(A) deamination of a cytosine base into a uracil base in the open reading frame
(B) A change from a TAA codon to a TAG codon in the coding region
(C) A sequence change in the 3' untranslated region
(D) A loss of a T in the coding region
(E) all of the above

13. The polymerase chain reaction (PCR) technique can be used for (A) direct isolation of a specific segment of genomic DNA. (B) preparation of probes. (C) synthesis of RNA from genomic DNA. (D) a and b (E) all of the above

14. In the large-scale production of a particular human protein in E. coli cells, the cDNA corresponding to the protein was modified so that the expressed protein would have six histidine residues at the C-terminus. The purpose of this modification was (A) to facilitate transfer of the cDNA into the E. coli cells. (B) to provide a promoter for the transcription of the cDNA in E. coli. (C) to facilitate purification of the expressed protein though binding to an affinity column. (D) to prevent degradation of the expressed protein by E. coli proteases.

15. The ability of DNA to denature is important for which process? (A) DNA synthesis (B) nucleic acid hybridization experiments (C) RNA synthesis (D) all of the above

16. Which of the following is not required for both DNA replication and RNA transcription? (A) DNA (B) primers (C) RNA (D) proteins

18. You are performing an experiment to assay phosphorylation of a substrate by a protein kinase. Based on the data in the table below, what do these experimental results suggest?(A) GTP is not required for phosphorylation. (B) The substrate can undergo autophosphorylation. (C) The substrate is not required for phosphorylation. (D) The protein kinase is required for phosphorylation.

19. Sorting of protein to mitochondria and chloroplasts is (A) cotranslational. (B) post-translational. (C) pretranslational. (D) quasitranslational.

20. Protein X contains seven transmembrane domains, with a short N-terminus and a long C-terminus. Following protein synthesis, the N-terminus of the protein faces the lumen (the inside) of the endoplasmic reticulum (ER). After protein X is transported to the cell surface via exocytosis, you would expect the C-terminus of the protein X to be (A) extracellular. (B) cytoplasmic. (C) in the lumen of ER. (D) in the lipid bilayer of the plasma membrane.

21. The genetic material of which kind of cells is included in a single, circular molecule of DNA? (A) bacteria (B) yeasts (C) flies (D) flowering plants

22. Kinases, which are responsible for the activation or inactivation of a number of proteins, can add phosphate groups onto (A) tryptophan residues. (B) tyrosine residues. (C) cysteine residues. (D) a and c. (E) none of the above

23. The dissociation constant (Ka) of the human serotonin receptor for serotonin is 1 x 10-10 M. What does this mean? (A) It means that when the concentration of the serotonin receptor is 1 x 10-10 M, half of the available serotonin receptor sites are occupied. (B) It means that when the concentration of the serotonin receptor is 1 x 10-10 M, all of the available serotonin receptor sites are occupied. (C) It means that when the concentration of serotonin is 1 x 10-10 M, all of the available serotonin receptor sites are occupied. (D) It means that when the concentration of serotonin is 1 x 10-10 M, half of the available serotonin receptor sites are occupied. (E) None of the above