複選題

6. Which of the following statements are true for the enzyme reverse transcriptase?
(A) It is sensitive to high temperatures and so can be readily "killed" by heat treatment when the reaction is completed.
(B) It does not require a primer to initiate polymerization as do most DNA polymerases.
(C) It is insensitive to high temperatures and so can survive the many cycles of heating required to perform the polymerase chain reaction.
(D) It is an RNA-dependent DNA polymerase.
(E) It lacks the proofreading function of most DNA polymerases and so is able to utilize mRNA from mutated genes as a template. 

2. When bacteria produce mammalian proteins, cDNA is used rather than genomic DNA. Which of the following is the best explanation? (A) It is easier to clone RNA than DNA. (B) It is not possible to clone the entire coding region of the gene. (C) It is easier to clone cDNA than genomic DNA of comparable size. (D) Most eukaryotic genes have introns that cannot be removed in bacteria. (E) Most eukaryotic gene promoters do not function in bacteria

3. Below is an electron micrograph of a gene that is being transcribed. The DNA strand runs horizontally with RNA transcripts extending vertically outward. What is the direction of movement of RNA polymerases along the length of DNA strand? (A) Upward (B) Downward (C) Rightward (D) Leftward (E) Can't be determined

複選題4. Which of the following statements are true? (A) Bacterial mRNA normally occurs as a double-stranded structure, with one strand containing codons, the other containing anticodons. (B) Bacterial mRNA is broken down within a few minutes of its formation in E. coli. (C) Bacterial mRNA consists only of the bases that code for amino acids. (D) The three ribosomal RNAs in a bacterial ribosome are distributed in three separate, large ribosomal subunits. (E) Bacterial mRNA can be translated while it is still being synthesized.

5. A microarray is a large collection of specific DNA oligonucleotides spotted in a defined pattern on a microscope slide. What is the most useful experiment that can be done with such a tool? (A) Evaluating the linkage relationships of genes (B) Comparing newly synthesized nuclear RNA with cytoplasmic RNA to locate introns (C) Comparing RNA produced under two different physiological conditions to understand patterns of gene expression (D) Comparing proteins produced under two different physiological conditions to understand their function (E) Predicting the presence of specific metabolites in a cell

7. Possesses genes that may be integrated into the genome of an infected eukaryotic cell(A) E. coli (B) Yeast (C) Retrovirus (D) Bacteriophage lambda (E) Adenovirus

8. Can lysogenize bacteria(A) E. coli (B) Yeast (C) Retrovirus (D) Bacteriophage lambda (E) Adenovirus 

9. The reason it takes approximately one hour before the first radioactively labeled mitotic cells are observed is that (A) cells must repair thymidine-induced DNA damage before entering G2 (B) the cells get out of synchrony as they proceed through the cell cycle (C) the period of thymidine labeling is 5 minutes (D) G2 lasts 1 hr (E) M phase lasts 1 hr

10. What percent of labeled cells are in M phase at 4 hours after exposure to labeled thymidine? (A) 100 (B) 33 (C) 20 (D) 6 (E) 0

11. If the length of G2 were increased by one hour, which of the following statements would be true regarding the slope of the line from the point of the first appearance of labeled mitotic cells to the first point at which all the mitotic cells were labeled? (A) It would stay the same. (B) It would decrease. (C) It would increase. (D) It would switch from a positive to a negative slope. (E) No conclusion regarding the slope of the line can be drawn.

12. The expected frequency of the triple CCC in the A: C=1:5 copolymer should be (A) 1/8 (B) 5/6 (C) 7/8 (D) 15/216 (E) 125/216