Chapter 8 Microbial Genetics
8.1 Multiple Choice Questions
1) A gene is best defined as
A) a segment of DNA.
B) three nucleotides that code for an amino acid.
C) a sequence of nucleotides in DNA that codes for a functional product. D) a sequence of nucleotides in RNA that codes for a functional product. E) a transcribed unit of DNA.
2) Which of the following pairs is mismatched?
A) DNA polymerase — makes a molecule of DNA from a DNA template B) RNA polymerase — makes a molecule of RNA from an RNA template C) DNA ligase — joins segments of DNA
D) transposase — insertion of DNA segments into DNA
E) DNA gyrase — coils and twists DNA
3) Which of the following statements is FALSE?
A) DNA polymerase joins nucleotides in one direction only.
B) The leading strand of DNA is made continuously.
C) The lagging strand of DNA is started by an RNA primer.
D) DNA replication proceeds in one direction around the bacterial chromosome. E) Multiple replication forks are possible on a bacterial chromosome. Answer: D
4) DNA is constructed of
A) a single strand of nucleotides with internal hydrogen bonding. B) two complementary strands of nucleotides bonded A—C and G—T. C) two strands of nucleotides running antiparallel.
D) two strands of identical nucleotides with hydrogen bonds between them. E) None of the answers is correct.
5) Which of the following is NOT a product of transcription? A) a new strand of DNA
E) None of the answers are correct; all of these are products of transcription. Answer: A
6) Which of the following statements about bacteriocins is FALSE? A) The genes coding for them are on plasmids.
B) They cause food-poisoning symptoms.
C) Nisin is a bacteriocin used as a food preservative.
D) They can be used to identify certain bacteria.
E) Bacteriocins kill bacteria.
7) In Figure 8.1, which colonies are streptomycin-resistant and leucine-requiring? A) 1, 2, 3, and 9
B) 3 and 9
C) 4, 6, and 8
D) 4 and 8
E) 5 and 6
Culture 1: F+, leucine+, histidine+
Culture 2: F-, leucine-, histidine-
8) In Table 8.1, what will be the result of conjugation between cultures 1 and 2? A) 1 will remain the same;
2 will become F+, leucine-, histidine-
B) 1 will become F-, leu+, his+;
2 will become F+, leu-, his-
C) 1 will become F-, leu-, his-;
2 will remain the same
D) 1 will remain the same;
2 will become F+, leu+, his+
E) 1 will remain the same;
2 will become F+ and recombination may occur
9) In Table 8.1, if culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures? A) They will both remain the same.
B) 1 will become F+, leu+, his+;
2 will become F+, leu+, his+
C) 1 will remain the same;
recombination will occur in 2
D) 1 will become F-, leu+, his+;
2 will become Hfr, leu+, his+
E) The answer cannot be determined based on the information provided. Answer: C
10) An enzyme produced in response to the presence of a substrate is called a(n) A) inducible enzyme.
B) repressible enzyme.
C) restriction enzyme.
11) When glucose is high, cAMP is _____ : CAP _____ bind the lac operator, and RNA polymerase _____ bind the lac promoter. A) high; does; does
B) low; does not; does not
C) high; does not; does
D) low; does not; does
E) None of the answers is correct.
12) Transformation is the transfer of DNA from a donor to a recipient cell A) by a bacteriophage.
B) as naked DNA in solution.
C) by cell-to-cell contact.
D) by crossing over.
E) by sexual reproduction....