Deck 8: Microbial Genetics

Question 1

Conjugation differs from reproduction because conjugation

A) transfers DNA vertically, to new cells.
B) replicates DNA.
C) copies RNA to make DNA.
D) transfers DNA horizontally, to cells in the same generation.
E) transcribes DNA to RNA.

Answer 1

D

Question 2

Figure 8.3 - Metabolic Pathway
In Figure 8.3, if enzyme A is an inducible enzyme,

A) compound C would bind to the repressor.
B) compound B would bind to enzyme A.
C) compound A would bind to the repressor.
D) compound C would react with gene a.
E) compound A would react with enzyme B.

Answer 2

C

Question 3

Table 8.2 $\begin{array} { | l | l | l | l | } \hline \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\hline \text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\hline \text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\hline \text { GUU } & \text { valine } & \begin{array} { l } \text { UCG, } \\\text { UCU }\end{array} & \text { serine } \\\hline\end{array}$ Codon on mRNA and corresponding amino acid

-Refer to Table 8.2. If the sequence of amino acids encoded by a strand of DNA is serine- alanine- lysine- leucine, what is the order of bases in the sense strand of DNA?

A) 3' AGACGTTTCAAT
B) 3' UGUGCAAAGUUA
C) 3' TCTCGTTTGTTA
D) 5' TGTGCTTTCTTA
E) 5' AGAGCTTTGAAT

Answer 3

3' AGACGTTTCAAT

Question 4

Figure 8.1

In Figure 8.1, which colonies are streptomycin- resistant and leucine- requiring?

A) 5 and 6
B) 4, 6, and 8
C) 1, 2, 3, and 9
D) 4 and 8
E) 3 and 9

Question 5

According to the operon model, for the synthesis of an inducible enzyme to occur, the

A) substrate must bind to the enzyme.
B) substrate must bind to the repressor.
C) repressor must bind to the operator.
D) end- product must not be in excess.
E) repressor must not be synthesized.

Question 6

An enzyme that copies DNA to make a molecule of RNA is

A) DNA polymerase.
B) transposase.
C) RNA polymerase.
D) DNA ligase.
E) DNA helicase.

Question 7

The mechanism by which the presence of arabinose controls the arabinose operon is

A) repression.
B) catabolite repression.
C) DNA polymerase.
D) translation.
E) induction.

Question 8

Figure 8.4

In Figure 8.4, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you can conclude that chloramphenicol

A) prevents translation in eukaryotes.
B) prevents mRNA- ribosome binding.
C) prevents translation in prokaryotes.
D) prevents transcription in prokaryotes.
E) prevents transcription in eukaryotes.

Question 9

Figure 8.5

In Figure 8.5, 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

Question 10

Which of the following statements is FALSE?

A) The lagging strand of DNA is started by an RNA primer.
B) DNA replication proceeds in one direction around the bacterial chromosome.
C) Multiple replication forks are possible on a bacterial chromosome.
D) The leading strand of DNA is made continuously.
E) DNA polymerase joins nucleotides in one direction only.

Question 11

Assume the two E.coli strains shown below are allowed to conjugate. 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, proline, histidine, methionine
B) ampicillin, prolein, histidine, lysine
C) ampicillin, lysine, arginine
D) proline, histidine, methionine
E) lysine, arginine

Question 12

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by

A) UV radiation.
B) DNA polymerase.
C) snRNPs.
D) photolyases.
E) a chemical mutagen.

Question 13

Figure 8.2
REPLICATION FORK
In Figure 8.2, base 2 is attached to

A) deoxyribose.
B) thymine.
C) phosphate.
D) ribose.
E) The answer cannot be determined based on the information provided.

Question 14

Table 8.1 $\text { Culture 1: F+, leucinet+, histidinet +}$
$\text { Culture 2: F-, leucine-, histidine- }$

-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 remain the same; recombination will occur in 2
C) 1 will become F^- , leu⁺, his⁺; 2 will become Hfr, leu+, his⁺
D) 1 will become F⁺, leu⁺, his⁺; 2 will become F⁺, leu⁺, his⁺
E) The answer cannot be determined based on the information provided.

Question 15

A gene is best defined as

A) three nucleotides that code for an amino acid.
B) a transcribed unit of DNA.
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 segment of DNA.

Question 16

Which of the following statements regarding a bacterium that is R⁺ is FALSE?

A) It possesses a plasmid.
B) R⁺ can be transferred to a cell of the same species.
C) R⁺ can be transferred to a different species.
D) It is F⁺.
E) It is resistant to certain drugs and heavy metals.

Question 17

Repair of damaged DNA might be viewed as a race between an endonuclease and

A) DNA ligase.
B) DNA polymerase.
C) helicase.
D) primase.
E) methylase.

Question 18

The damage caused by ultraviolet radiation is

A) repaired during transcription.
B) repaired during translation.
C) cut out and replaced.
D) never repaired.
E) repaired by DNA replication.

Question 19

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) Bacteriocins kill bacteria.
D) Nisin is a bacteriocin used as a food preservative.
E) They can be used to identify certain bacteria.

Question 20

Which of the following pairs is mismatched?

A) DNA ligase - joins segments of DNA
B) RNA polymerase - makes a molecule of RNA from an RNA template
C) DNA polymerase - makes a molecule of DNA from a DNA template
D) DNA gyrase - coils and twists DNA
E) transposase - insertion of DNA segments into DNA

Question 21

Synthesis of a repressible enzyme is stopped by the

A) substrate binding to the repressor.
B) end product binding to the promoter.
C) corepressor binding to the operator.
D) corepressor- repressor complex binding to the operator.
E) allosteric transition.

Question 22

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes

A) require snRNPS.
B) use codons to determine polypeptide sequences.
C) have exons.
D) have introns.
E) use methionine as the "start" amino acid.

Question 23

Figure 8.3 - Metabolic Pathway
In Figure 8.3, if enzyme A is a repressible enzyme, compound C would

A) bind to the enzyme.
B) bind to RNA polymerase.
C) bind to gene a.
D) always be in excess.
E) bind to the corepressor.

Question 24

Table 8.1 $\text { Culture 1: F+, leucinet+, histidinet +}$
$\text { Culture 2: F-, leucine-, histidine- }$

-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 remain the same
C) 1 will become F^- , leu⁺, his⁺; 2 will become F⁺, leu^- , his^-
D) 1 will remain the same; 2 will become F⁺ and recombination may occur
E) 1 will remain the same; 2 will become F⁺, leu⁺, his⁺

Question 25

The initial effect of ionizing radiation on a cell is that it causes

A) bonding between adjacent thymines.
B) DNA to break.
C) base substitutions.
D) the cells to get hot.
E) the formation of highly reactive ions.

Question 26

Genetic change in bacteria can be brought about by

A) transduction.
B) conjugation.
C) transformation.
D) mutation.
E) All of the answers are correct.

Question 27

An enzyme that catalyzes the cutting and resealing of DNA, and is translated from insertion sequences, is

A) RNA polymerase.
B) DNA polymerase.
C) transposase.
D) DNA ligase.
E) DNA helicase.

Question 28

Figure 8.3 - Metabolic Pathway
In Figure 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify

A) transcription.
B) feedback inhibition.
C) a mutation.
D) repression.
E) competitive inhibition.

Question 29

An enzyme that makes covalent bonds between nucleotide sequences in DNA is

A) DNA polymerase.
B) DNA ligase
C) RNA polymerase.
D) transposase.
E) DNA helicase.

Question 30

The miRNAs in a cell

A) are responsible for inducing operons.
B) allow different cells to produce different proteins.
C) are found in prokaryotic cells.
D) are a part of the prokaryotic ribosome.
E) are a part of the eukaryotic ribosome.

Question 31

Which of the following is NOT a product of transcription?

A) mRNA
B) tRNA
C) rRNA
D) a new strand of DNA
E) None of the answers are correct; all of these are products of transcription.

Question 32

Figure 8.2
REPLICATION FORK
In Figure 8.2, if base 4 is thymine, what is base 11'?

A) guanine
B) uracil
C) thymine
D) adenine
E) cytosine

Question 33

Table 8.2
Codon on mRNA and corresponding amino acid $\begin{array} { | l | l | l | l | } \hline \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\hline \text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\hline \text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\hline \text { GUU } & \text { valine } & \begin{array} { l } \text { UCG, } \\\text { UCU }\end{array} & \text { serine } \\\hline\end{array}$

-Refer to Table 8.2. If the sequence of amino acids encoded 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' TCACGUUUCAAU.
D) 3' UGUGCAAAGUUA.
E) 3' UCUCGAAAGUUA.

Question 34

An enzyme produced in response to the presence of a substrate is called a(n)

A) promoter.
B) restriction enzyme.
C) repressible enzyme.
D) inducible enzyme.
E) operator.

Question 35

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) The answer cannot be determined based on the information provided.

Question 36

Table 8.3
Amino Acids Encoded by the Human p53 Gene

Based on the information in Table 8.3, prostate cancer is probably the result of which kind of mutation?

A) nonsense
B) analog
C) missense
D) frameshift
E) None of the answers is correct.

Question 37

Table 8.2
Codon on mRNA and corresponding amino acid $\begin{array} { | l | l | l | l | } \hline \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\hline \text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\hline \text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\hline \text { GUU } & \text { valine } & \begin{array} { l } \text { UCG, } \\\text { UCU }\end{array} & \text { serine } \\\hline\end{array}$

-Refer to Table 8.2 The anticodon for valine is

A) GUU.
B) CUU.
C) CAA.
D) CTT.
E) GTA.

Question 38

The mechanism by which the presence of glucose inhibits the arabinose operon is

A) catabolite repression.
B) repression.
C) DNA polymerase.
D) translation.
E) induction.

Question 39

Transformation is the transfer of DNA from a donor to a recipient cell

A) by cell- to- cell contact.
B) by sexual reproduction.
C) as naked DNA in solution.
D) by crossing over.
E) by a bacteriophage.

Question 40

Table 8.2
Codon on mRNA and corresponding amino acid $\begin{array} { | l | l | l | l | } \hline \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\hline \text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\hline \text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\hline \text { GUU } & \text { valine } & \begin{array} { l } \text { UCG, } \\\text { UCU }\end{array} & \text { serine } \\\hline\end{array}$

-Refer to Table 8.2. What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA? 3' ATTACGCTTTGC

A) asparagine- arginine- lysine- alanine
B) asparagine- cysteine- valine- serine
C) leucine- arginine- lysine- alanine
D) Translation would stop at the first codon.
E) The answer cannot be determined based on the information provided.

Question 41

Mutations that are harmful to cells occur more frequently than those that benefit cells.

Question 42

Cell- to- cell contact is required for transduction to occur.

Question 43

When glucose is high, cAMP is : CAP bind the lac operator, and RNA polymerase bind the lac promoter.

A) high; does not; does
B) low; does not; does not
C) high; does; does
D) low; does not; does
E) None of the answers is correct.

Question 44

In the Ames test, any colonies that form on the control should be the result of spontaneous mutations.

Question 45

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.

Question 46

The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA.

Question 47

Open- reading frames are segments of DNA in which both start and stop codons are found.

Question 48

Bacteria typically contain multiple chromosomes.

Question 49

Some organisms may contain multiple genomes.

Question 50

Scientists are concerned that bacteria will be resistant to all antibiotics within the next decade. Using your knowledge of genetics, describe how bacterial populations can develop drug resistance in such a short time frame.

Question 51

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 identical nucleotides with hydrogen bonds between them.
D) two strands of nucleotides running antiparallel.
E) None of the answers is correct.

Question 52

Both base substitution and frameshift mutations can result in the formation of premature stop codons.

Question 53

Recombination will always alter a cell's genotype.

Question 54

Transposition results in the formation of base substitution mutations in a cell's DNA.

Question 55

Table 8.2
Codon on mRNA and corresponding amino acid $\begin{array} { | l | l | l | l | } \hline \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\hline \text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\hline \text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\hline \text { GUU } & \text { valine } & \begin{array} { l } \text { UCG, } \\\text { UCU }\end{array} & \text { serine } \\\hline\end{array}$

-Refer to Table 8.2. If a frameshift mutation occurred in the sequence of bases shown below, what would be the sequence of amino acids coded for? 3' ATTACGCTTTGC

A) asparagine- cysteine- valine- serine
B) leucine- arginine- lysine- alanine
C) asparagine- arginine- lysine- alanine
D) Translation would stop at the first codon.
E) The answer cannot be determined based on the information provided.

Question 56

Figure 8.2
REPLICATION FORK
In Figure 8.2, if base 4 is thymine, what is base 4'?

A) thymine
B) cytosine
C) adenine
D) uracil
E) guanine