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

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

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

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.

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

24. Which of the following sequential order for the secretory pathway is false? (A) Rough endoplasmic reticulum (ER) → ER-to-Golgi transport vesicles → Golgi cisternae → secretory vesicles. (B) Rough ER → ER-to-Golgi transport vesicles → Golgi cisternae → Mitochondria. (C) Plasma membrane → Early endosome → Late endosome → Lysosome. (D) Rough ER → ER-to-Golgi transport vesicles → Golgi cisternae → Late endosome → Lysosome.

25. The first step in the secretory pathway that should be inhibited by a dominant-negative mutant of SNARE proteins is (A) rough endoplasmic reticulum to Golgi transport. (B) intra Golgi transport. (C) trans Golgi network (TGN) transport to the plasma membrane. (D) TGN transport to the late endosome.