Question 1

Which of the following statements CORRECTLY describes nonsense mutations?

Accepted Answer

A)   They cause a nonfunctional amino acid to replace a functional amino acid.
B)   They change the nucleotide sequence of a gene but do not change the sequence of the resulting protein.
C)   They result in the insertion or deletion of a small number of nucleotides to the DNA.
D)   They convert a codon for a particular amino acid within a gene into a stop codon.
E)   They cannot revert to wild type.

Question 2

Do you believe that transposable elements (TEs) are best described as "parasitic" DNA sequences, simply using the host genome as a means to replicate and spread and providing no benefit for the host, or do you believe that they provide some adaptive advantage for the host genomes that house them? Explain. If you believe that TEs are advantageous to the host, give some specific examples to support this conclusion.

Accepted Answer

Transposable elements (TEs) are often re...

Question 3

A _____ mutation changes a codon that specifies an amino acid into one that terminates translation.

Accepted Answer

A)   missense
B)   nonsense
C)   silent
D)   neutral
E)   reverse

Question 4

(a) List the two major pathways in eukaryotes for repairing double-stranded breaks in DNA molecules. (b) Explain the need for each pathway.

Accepted Answer

(a) The two major pathways in eukaryotes...

Question 5

_____ mutations produce new activities and are usually dominant.

Accepted Answer

A)   Induced
B)   Spontaneous
C)   Forward
D)   Gain-of-function
E)   Lethal

Question 6

Tumor suppressor proteins can assist in slowing down the cell cycle under appropriate conditions. In humans, the TP53 gene encodes a tumor suppressor called p53. Most mutations in the TP53 gene result in a mutant form of p53 that can no longer function to slow down the cell cycle, which can lead to a cell becoming cancerous. However, some mutant forms of p53 actually possess the ability to increase a cell's resistance to anticancer treatments. Which of the following BEST describes this type of mutation?

Accepted Answer

A)   loss-of-function mutation
B)   gain-of-function mutation
C)   reverse mutation
D)   suppressor mutation
E)   neutral mutation

Question 7

In a eukaryotic cell, two different transposable elements, each containing an intron, excise and insert in different locations within the genome. After transposition, the transposable elements are sequenced at their new sites. Explain the following sequencing results:
a. Neither of the translocated transposable elements contains any intron sequences.
b. One of the transposable elements contains the intron, but the other transposable element does not.

Accepted Answer

a. The sequencing results indicate that ...

Question 8

Which of the following enzyme activities play a role in nucleotide-excision repair? (Select all that apply.)

Accepted Answer

A)   DNA polymerase
B)   DNA ligase
C)   reverse transcriptase
D)   DNA helicase
E)   primase

Question 9

Which of the following statements BEST describes the Activator (Ac)  and Dissociation (Ds)  transposable elements in maize (corn) ?

Accepted Answer

A)   Ac elements cannot transpose unless a Ds element is present.
B)   Ac contains a functional transposase gene; Ds lacks a functional transposase gene.
C)   Ds contains a functional transposase gene; Ac lacks a functional transposase gene.
D)   Both Ac and Ds have functional transposase genes.
E)   Neither Ac nor Ds contains functional transposase genes.

Question 10

Which of the following statements about an animal bearing a somatic mutation is TRUE?

Accepted Answer

A)   Some, but not all, of the animal's offspring will also carry the mutation.
B)   All of the animal's offspring will carry the mutation.
C)   Both the animal and its offspring will show the mutant trait.
D)   The animal but not its offspring can be affected by the mutation.
E)   The gametes produced by the animal will all carry the mutation.

Question 11

Composite transposons in bacteria are characterized by which of the following?

Accepted Answer

A)   They are composites of Ac and Ds elements.
B)   Each has the ability to transpose either by replicative transposition or nonreplicative transposition.
C)   They contain all deleted transposase genes.
D)   They contain more than one gene.
E)   No correct answer is provided.

Question 12

Which of the following transposable elements have indirect repeats at each end?

Accepted Answer

A)   Ac in maize
B)   Ty in yeast
C)   copia in Drosophila
D)   Alu in humans
E)   All of the answers are correct.

Question 13

Consider two theoretical transposable elements in yeast, A and B. Each contains an intron and each transposed to a new location in the yeast genome. Suppose you then examine the transposons for the presence of the intron. In the new locations, you find that A has no intron but B does. From these facts, what can you conclude about the mechanisms of transposition for the two transposable elements?

Accepted Answer

A)   B probably makes a transposase.
B)   A probably has inverted repeats at each end of the element.
C)   B probably uses RNA as an intermediate in the transposition event.
D)   B probably makes a reverse transcriptase.
E)   A probably doesn't create a duplication of the host genome target sequence.

Question 14

What is the consequence of a transversion mutation in duplex DNA?

Accepted Answer

A)   A purine is replaced by a pyrimidine, and a pyrimidine is replaced by a purine.
B)   A base pair is lost within the DNA of a gene, which causes a reading frameshift.
C)   A purine is replaced by another purine, and a pyrimidine is replaced by another pyrimidine.
D)   A base pair is added to the DNA within a gene, which causes a reading frameshift.
E)   The sequence of the DNA remains the same since the change involves proteins.

Question 15

List all single-base substitutions that would change a codon for Leu to a nonsense codon (see Figure 15.12). For each, indicate whether it would be a transition or transversion.

Accepted Answer

Leucine (Leu) is encoded by six differen...

Question 16

Using diagrams, compare and contrast an insertion sequence with a composite transposon. Label the important features of both.

Accepted Answer

An insertion sequence (IS) and a composi...

Question 17

The mutagen EMS converts guanine (G) to O-6-ethylguanine (G*). O-6-ethylguanine (G*) forms base pairs with thymine (T) instead of cytosine (C). Suppose that exposure to EMS damages a DNA molecule as shown below:  a. Diagram the steps required for the incorporated G* to induce a stably inherited mutation. Your diagram should include all necessary rounds of replication.
b. Characterize the mutation induced by EMS as a transition, transversion, or frameshift.

Accepted Answer

The answer of The mutagen EMS converts guanine (G) to...

Question 18

Which of the following characterizes the mode of transposition of retrotransposons?

Accepted Answer

A)   It involves an RNA intermediate.
B)   It involves the initial synthesis of transposase.
C)   It involves the production of a protein repressor.
D)   It only occurs in nondividing host genomes.
E)   It requires inverted repeats at each end of the retrotransposon.

Question 19

Which of the following kinds of mutations is MOST likely to be a null loss-of-function mutation?

Accepted Answer

A)   transition
B)   transversion
C)   frameshift
D)   missense
E)   induced

Question 20

How do germ-line mutations differ from somatic mutations?

Accepted Answer

A)   Germ-line mutations involve small changes to DNA such as base-pair substitutions, while somatic mutations usually involve large deletions.
B)   Germ-line mutations occur during DNA replication, while somatic mutations do not.
C)   Germ-line mutations can be passed on to offspring, while somatic mutations cannot.
D)   Germ-line mutations are reversible, while somatic mutations are not.
E)   Germ-line mutations result in cancers, while somatic mutations do not.

Exam 18: Gene Mutations and Dna Repair

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Which of the following characterizes the mode of transposition of retrotransposons?

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How do germ-line mutations differ from somatic mutations?

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Which of the following transposable elements have indirect repeats at each end?

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List all single-base substitutions that would change a codon for Leu to a nonsense codon (see Figure 15.12). For each, indicate whether it would be a transition or transversion.

Correct Answer
Answered by ExamLex AI
Leucine (Leu) is encoded by six differen...
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What is the consequence of a transversion mutation in duplex DNA?

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A _____ mutation changes a codon that specifies an amino acid into one that terminates translation.

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Which of the following enzyme activities play a role in nucleotide-excision repair? (Select all that apply.)

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_____ mutations produce new activities and are usually dominant.

Correct Answer
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Correct Answer
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Using diagrams, compare and contrast an insertion sequence with a composite transposon. Label the important features of both.

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An insertion sequence (IS) and a composi...
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a. The sequencing results indicate that ...
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Composite transposons in bacteria are characterized by which of the following?

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Which of the following statements about an animal bearing a somatic mutation is TRUE?

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Which of the following kinds of mutations is MOST likely to be a null loss-of-function mutation?

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(a) List the two major pathways in eukaryotes for repairing double-stranded breaks in DNA molecules. (b) Explain the need for each pathway.

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Answered by ExamLex AI
(a) The two major pathways in eukaryotes...
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Which of the following statements BEST describes the Activator (Ac) and Dissociation (Ds) transposable elements in maize (corn) ?

Correct Answer
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Correct Answer
Answered by ExamLex AI
Transposable elements (TEs) are often re...
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Which of the following statements CORRECTLY describes nonsense mutations?

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Exam 18: Gene Mutations and Dna Repair

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Which of the following characterizes the mode of transposition of retrotransposons?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

How do germ-line mutations differ from somatic mutations?

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Which of the following transposable elements have indirect repeats at each end?

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List all single-base substitutions that would change a codon for Leu to a nonsense codon (see Figure 15.12). For each, indicate whether it would be a transition or transversion.

Correct AnswerAnswered by ExamLex AILeucine (Leu) is encoded by six differen...View AnswerShow Answer

What is the consequence of a transversion mutation in duplex DNA?

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A _____ mutation changes a codon that specifies an amino acid into one that terminates translation.

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Which of the following enzyme activities play a role in nucleotide-excision repair? (Select all that apply.)

Correct AnswerverifiedShow Answer

_____ mutations produce new activities and are usually dominant.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Using diagrams, compare and contrast an insertion sequence with a composite transposon. Label the important features of both.

Correct AnswerAnswered by ExamLex AIAn insertion sequence (IS) and a composi...View AnswerShow Answer

Correct AnswerAnswered by ExamLex AIa. The sequencing results indicate that ...View AnswerShow Answer

Composite transposons in bacteria are characterized by which of the following?

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Which of the following statements about an animal bearing a somatic mutation is TRUE?

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Which of the following kinds of mutations is MOST likely to be a null loss-of-function mutation?

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(a) List the two major pathways in eukaryotes for repairing double-stranded breaks in DNA molecules. (b) Explain the need for each pathway.

Correct AnswerAnswered by ExamLex AI(a) The two major pathways in eukaryotes...View AnswerShow Answer

Which of the following statements BEST describes the Activator (Ac) and Dissociation (Ds) transposable elements in maize (corn) ?

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Correct AnswerAnswered by ExamLex AITransposable elements (TEs) are often re...View AnswerShow Answer

Which of the following statements CORRECTLY describes nonsense mutations?

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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
Answered by ExamLex AI
Leucine (Leu) is encoded by six differen...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
Answered by ExamLex AI
An insertion sequence (IS) and a composi...
View Answer

Correct Answer
Answered by ExamLex AI
a. The sequencing results indicate that ...
View Answer

Correct Answer
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Correct Answer
verified

Correct Answer
verified

Correct Answer
Answered by ExamLex AI
(a) The two major pathways in eukaryotes...
View Answer

Correct Answer
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Correct Answer
Answered by ExamLex AI
Transposable elements (TEs) are often re...
View Answer

Correct Answer
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