6. As the two strands of DNA are unraveled, an enzyme relieves the strain on the two strands. The enzyme is
(A) DNA polymerase III.
(B) DNA polymerase I.
(C) DNA helicase.
(D) DNA gyrase.
(E) DNA ligase.

2. Which of the following enzymes will produce a blunt end (the cut site is indicated by the * in the recognition sequence)? (A) Taql (T*CGA) (B) Eagl (C*GGCCG) (C) EcoRV (GAT*ATC) (D) Nsil (ATGCA*T)

3. DNA primase (A) creates a short RNA primer complementary to the RNA template. (B) creates a short DNA primer complementary to the RNA template. (C) creates a short DNA primer complementary to the DNA template. (D) creates a short DNA primer complementary to the DNA template.

4. The lagging strand is replicated with stretches of Okazaki fragments and that is why its synthesis is considered to be (A) discontinuous. (B) primed. (C) never stopping. (D) semiconservative.

5. A scientist developed a particular chemical to bind with adenine. If this chemical were applied prior to the S phase in the cell cycle, what might be a logical prediction of the outcome? (A) The DNA replication would proceed except that adenine would have the chemical bound to it and is incorporated into the new sister chromatids. (B) The DNA replication would proceed except that everywhere an adenine was supposed to be, a thymine was substituted into the new developing strand. (C) The DNA replication would proceed because cytosine and guanine would continue to form base pairs. (D) The DNA replication would stop because if adenine was bound then thymine would not have a complement with which to base pair.

7. Which of the following enzymes removes the primers used for DNA replication? (A) DNA polymerase I (B) DNA polymerase II (C) DNA polymerase III (D) DNA ligase

8. If you were able to look very closely at a portion of DNA and find methylated histones, you would (A) be mistaken since only DNA can be methylated, not histones. (B) be looking at a region of active chromatin. (C) be looking at a region of inactive chromatin. (D) be looking at transcription initiation.

9. A mutation in one gene that counteracts the effects of a mutation in another gene is known as a (A) temperature-sensitive mutation. (B) recessive mutation. (C) conditional mutation. (D) suppressor mutation.

10. You are studying the function of a recently identified gene in C. elegans. You have been performing genetic screens for several months in an attempt to isolate loss-of-function mutations in this gene, but unfortunately you have been unsuccessful. Your advisor suggests that you try another approach to eliminate gene function. Which of the following techniques would accomplish this goal? (A) Design a repressor to bind to the operon of this gene. (B) Use a histone deacetylase to induce a transcriptionally inactive state. (C) Use a C. elegans strain with a homozygous TFIID mutation to prevent the translation initiation complex from forming. (D) Use RNA interference to prevent mRNA translation.

11. Which of the following statements regarding the ubiquitin-proteosome pathway is false? (A) This pathway is used to regulate expression of a number of cell surface receptors. (B) When proteins are destroyed by the proteosome, the ubiquitin moiety is not destroyed, but rather cleaved off and reused. (C) Ubiquitin ligase adds ubiquitin residues to targeted proteins in a stepwise fashion. (D) Ubiquitination of a targeted protein requires only one molecule of ATP.

複選題12. The p300/CBP (CREB-binding protein) coactivator proteins are histone acetyltransferases that help regulate the transcription of many genes. Based on this information, these proteins are involved in (A) DNA acetylation. (B) chromatin remodeling. (C) recruitment of RNA polymerase II. (D) formation of the transcription initiation complex.