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Microbiology, 9e (Tortora)
Chapter 8
Objective 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.
4) Two E.coli strains are shown below:
Hfr: pro+, arg+, his+, lys+, met+, ampicillin-sensitive
F: pro-, arg-, his-, lys-, met-, ampicillin-resistant
What supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys +,
arg+, amp-resistant?
A) Ampicillin, lysine, arginine
B) Lysine arginine
C) Ampicillin, proline, histidine, methionine
D) Proline, histidine, methionine
E) Ampicillin, prolein, histidine, lysine
Microbiology, 9e (Tortora)
Chapter 8
Figure 8.1
5) 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
6) Which of the following is not a product of transcription?
A) A new strand of DNA
B) rRNA
C) tRNA
D) mRNA
E) None of the above
Microbiology, 9e (Tortora)
Chapter 8
7) All of the following are true about bacteriocins except
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) Bacteria that produce bacteriocins are resistant to their own bacteriocins.
E) None of the above.
Table 8.1
+
Culture 1: F , leucine+, histidine+
Culture 2: F-, leucine-, histidine8) 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-, histidineB) 1 will become F-, leu+, his+;
2 will become F+, leu-, hisC) 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) Can't tell
10) An enzyme produced in response to the presence of a substrate is called
A) An inducible enzyme.
B) A repressible enzyme.
C) A restriction enzyme.
D) An operator.
E) A promoter.
Microbiology, 9e (Tortora)
Chapter 8
11) Which of the following proteins are not coded for by genes carried on plasmids?
A) Enzymes necessary for conjugation
B) Enzymes that catabolize hydrocarbons
C) Bacteriocins
D) Enzymes that inactivate antibiotics
E) None of the above
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.
13) Genetic change in bacteria can be brought about by
A) Mutation.
B) Conjugation.
C) Transduction.
D) Transformation.
E) All of the above.
14) Which of the following is not true of a bacterium that is R+?
A) R+ refers to the possession of a plasmid.
B) R+ can be transferred to a recipient cell.
C) It is resistant to certain drugs and heavy metals.
D) It is F+.
E) None of the above.
15) The initial effect of ionizing radiation on a cell is that it causes
A) DNA to break.
B) Bonding between adjacent thymines.
C) Base substitutions.
D) The formation of highly reactive ions.
E) The cells to get hot.
Microbiology, 9e (Tortora)
Chapter 8
16) According to the operon model, for the synthesis of an inducible enzyme to occur, the
A) End-product must not be in excess.
B) Substrate must bind to the enzyme.
C) Substrate must bind to the repressor.
D) Repressor must bind to the operator.
E) Repressor must not be synthesized.
17) Synthesis of a repressible enzyme is stopped by
A) The allosteric transition.
B) The substrate binding to the repressor.
C) The corepressor binding to the operator.
D) The corepressor-repressor binding to the operator.
E) The end-product binding to the promoter.
Figure 8.2
18) In Figure 8.2, if base 4 is thymine, what is base 4'?
A) Adenine
B) Thymine
C) Cytosine
D) Guanine
E) Uracil
Microbiology, 9e (Tortora)
Chapter 8
19) In Figure 8.2, if base 4 is thymine, what is base 11'?
A) Adenine
B) Thymine
C) Cytosine
D) Guanine
E) Uracil
20) In Figure 8.2, base 2 is attached to
A) Ribose.
B) Phosphate.
C) Deoxyribose.
D) Thymine.
E) Can't tell.
21) The damage caused by ultraviolet radiation is
A) Never repaired.
B) Repaired during transcription.
C) Repaired during translation.
D) Cut out and replaced.
E) Repaired by DNA replication.
Table 8.2
Codon on mRNA and corresponding amino acid
UUA
leucine
UAA
nonsense
GCA
alanine
AAU
sparagine
AAG
lysine
UGC
cysteine
GUU
valine
UCG, UCU serine
22) (Use Table 8.2.) If the sequence of amino acids coded for by a strand of DNA is serine-alanine-lysine-leucine,
what is the order of bases in the sense strand of DNA?
A) UGUGCAAAGUUA
B)
AGACGTTTCAAT
C)
TCTCGTTTGTTA
D)
TGTGCTTTCTTA
E)
AGAGCTTTGAAT
Microbiology, 9e (Tortora)
Chapter 8
23) (Use Table 8.2.) If the sequence of amino acids coded for by a strand of DNA is serine-alanine-lysine-leucine,
the coding for the antisense strand of DNA is
A) 5´ ACAGTTTCAAT
B) 5´ TCTGCAAAGTTA
C) 3´ UGUGCAAAGUUA
D) 3´ UCUCGAAAGUUA
E) 3´ TCACGUUUCAAU
24) (Use Table 8.2.) The anticodon for valine is
A) GUU
B) CUU
C) CTT
D) CAA
E) GTA
25) (Use Table 8.2.) What is the sequence of amino acids coded for by the following sequence of bases in a strand
of DNA?
3´ ATTACGCTTTGC
A)
B)
C)
D)
E)
Leucine-arginine-lysine-alanine
Asparagine-arginine-lysine-alanine
Asparagine-cysteine-valine-serine
Transcription would stop at the first codon
Can't tell
26) (Use Table 8.2.) If a frameshift mutation occurred in a sequence of bases shown below, what would be the
sequence of amino acids coded for?
3´ ATTACGCTTTGC
A)
B)
C)
D)
E)
Leucine-arginine-lysine-alanine
Asparagine-arginine-lysine-alanine
Asparagine-cysteine-valine-serine
Translation would stop at the first codon
Can't tell
27) In Table 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify
A) A mutation.
B) End-product repression.
C) Feedback inhibition.
Microbiology, 9e (Tortora)
Chapter 8
D) Competitive inhibition.
E) None of the above.
28) In Table 8.3, if enzyme A is a repressible enzyme, compound C would
A) Always be in excess.
B) Bind to the enzyme.
C) Bind to the corepressor.
D) All of the above.
E) None of the above.
29) In Table 8.3, if enzyme A is an inducible enzyme,
A) Compound C would bind to the repressor.
B) Compound A would bind to the repressor.
C) Compound B would bind to enzyme A.
D) Compound A would react with enzyme B.
E) None of the above.
30) Conjugation differs from reproduction because conjugation
A) Replicates DNA.
B) Transfers DNA vertically, to new cells.
C) Transfers DNA horizontally, to cells in the same generation.
D) Transcribes DNA to RNA.
E) None of the above.
Microbiology, 9e (Tortora)
Chapter 8
31) The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is
from Thermus aquaticus and the template is from a human cell. The DNA synthesized would be most similar
to
A) Human DNA.
B) T. aquaticus DNA.
C) A mixture of human and T. aquaticus DNA.
D) Human RNA.
E) T. aquaticus RNA.
32) An antibiotic that binds the 50S portion of the ribosome as shown above would
A) Stop the ribosome from moving along the mRNA.
B) Prevent tRNA attachment.
C) Prevent peptide bond formation.
D) Prevent transcription.
E) None of the above.
Figure 8.3
33) In Figure 8.3, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you
can conclude that chloramphenicol
A) Prevents transcription in eukaryotes.
B) Prevents translation in eukaryotes.
C) Prevents transcription in prokaryotes.
D) Prevents translation in prokaryotes.
E) Prevents mRNA-ribosome binding.
Microbiology, 9e (Tortora)
Chapter 8
34) The mechanism by which the presence of glucose inhibits the arabinose operon.
A) Catabolic repression
B) Translation
C) DNA polymerase
D) Repression
E) Induction
35) The mechanism by which the presence of arabinose controls the arabinose operon.
A) Catabolic repression
B) Translation
C) DNA polymerase
D) Repression
E) Induction
36) If you knew the sequence of nucleotides within a gene, which one of the following could you determine with
the most accuracy?
A) The primary structure of the protein
B) The secondary structure of the protein
C) The tertiary structure of the protein
D) The quaternary structure of the protein
E) Can't tell
37) An enzyme that covalently bonds nucleotide sequences in DNA is
A) RNA polymerase.
B) DNA ligase.
C) Restriction enzyme.
D) Transposase.
E) DNA polymerase.
38) An enzyme that copies DNA to make a molecule of RNA is
A) RNA polymerase.
B) DNA ligase.
C) Restriction enzyme.
D) Transposase.
E) DNA polymerase.
Microbiology, 9e (Tortora)
Chapter 8
39) An enzyme that cuts double-stranded DNA at specific nucleotide sequences.
A) RNA polymerase
B) DNA ligase
C) Restriction enzyme
D) Transposase
E) DNA polymerase
40) An enzyme that cuts and seals DNA.
A) RNA polymerase
B) DNA ligase
C) Restriction enzyme
D) Transposase
E) DNA polymerase
Microbiology, 9e (Tortora)
Chapter 8
Figure 8.4
41) In Figure 8.4, which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein
when the structural genes are being transcribed?
A) a
B) b
C) c
D) d
E) e
42) In transcription,
A) DNA is changed to RNA.
B) DNA is copied to RNA.
C) DNA is replicated.
D) RNA is copied to DNA.
E) Proteins are made.
Microbiology, 9e (Tortora)
Chapter 8
43) DNA is constructed of
A) A single strand of nucleotides with internal hydrogen bonding.
B) 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 above.
44) The lac operon
A) Hydrolyzes lactose.
B) Produces constitutive enzymes.
C) Produces inducible enzymes.
D) Produces repressible enzymes.
E) None of the above.
45) A cell that cannot make tRNA
A) Can make proteins if amino acids are provided in the growth medium.
B) Can make proteins if mRNA is provided in the growth medium.
C) Can't make proteins unless aminoacyl synthetase is provided in the growth medium.
D) Can't make proteins.
E) None of the above.
Answer: D
Skill: Analysis