Question 1

What is the function of DNA glycosylases?

Accepted Answer

A) Recognize and cleave phosphodiester bonds in DNA 
B) Recognize and remove modified bases from the sugar component of DNA 
C) Reattach the two parts of DNA that result from double-strand breaks 
D) Remove pyrimidine dimers from DNA of E.coli that result from exposure to UV light 
E) Prevent strand slippage during DNA replication 
A) Recognize and cleave phosphodiester bonds in DNA 
B) Recognize and remove modified bases from the sugar component of DNA 
C) Reattach the two parts of DNA that result from double-strand breaks 
D) Remove pyrimidine dimers from DNA of E.coli that result from exposure to UV light 
E) Prevent strand slippage during DNA replication

Question 2

You are working on an insulin-binding protein from fish.The beginning of the coding sequence of the gene is shown below.You find a mutant in the gene that cannot bind insulin (also shown below).Among a population of fish that have the gene for the mutant protein, you find one that produces a variant of this protein that can now bind insulin again (DNA sequence also shown below).What kind of mutation is this new variant? (Use a genetic rather than a biochemical classification.)

Accepted Answer

The mutation in the new variant restores

Question 3

What is the difference between a missense mutation and a nonsense mutation?

Accepted Answer

Missense mutations alter the coding sequ

Question 4

The mutation shown in the diagram below can best be described as a _____ mutation.

Accepted Answer

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

Question 5

Helen has type I osteogenesis imperfecta (OI), a genetic skeletal disorder.Shown below is her DNA sequence for a portion of the coding region of the collagen type I gene, which contains the mutation responsible for her disorder.The corresponding wild-type sequence is shown also (only one DNA strand is shown in each case). Helen 5'-AAACTCCACTTCTTCCAGTAC-3'
Normal 5'-AAACTCACTTCTTCCAGTAC-3'
What type of mutation does Helen carry?

Accepted Answer

A) Missense 
B) Nonsense 
C) Silent 
D) Deletion 
E) Frameshift 
A) Missense 
B) Nonsense 
C) Silent 
D) Deletion 
E) Frameshift

Question 6

A company has invented a new low-calorie sugar substitute.They want to determine if the substitute might be carcinogenic, so they use it in the Ames test.The results show no increase in mutant bacterial colonies.They then perform feeding experiments in laboratory rats and find a significant increase in the incidence of cancer.Offer an explanation for why the Ames test did not accurately predict the carcinogenic potential of the sugar substitute, and suggest a solution to the problem.

Accepted Answer

The Ames test can give results only for

Question 7

Why do disruptive DNA lesions, like deletions and insertions, sometimes not lead to frameshift mutations?

Accepted Answer

Because amino acid codons consist of thr

Question 8

In the Ames test, what types of mutations are used to test for chemical mutagens?

Accepted Answer

A) his- to his+ mutations 
B) pro- to pro+ mutations 
C) pro+ to pro-mutations 
D) his+ to his- mutations 
E) trp+ to trp- mutations 
A) his- to his+ mutations 
B) pro- to pro+ mutations 
C) pro+ to pro-mutations 
D) his+ to his- mutations 
E) trp+ to trp- mutations

Question 9

Fragile-X syndrome is an example of a disease caused by what type of mutation?

Accepted Answer

A) Nonsense mutation 
B) Frameshift mutation 
C) Expanding nucleotide repeat 
D) Loss-of-function 
E) Gain-of-function 
A) Nonsense mutation 
B) Frameshift mutation 
C) Expanding nucleotide repeat 
D) Loss-of-function 
E) Gain-of-function

Question 10

Practically all transposable elements that have been studied are associated with which of the following?

Accepted Answer

A) Indirect repeats at each end 
B) A gene for transposase 
C) A gene for reverse transcriptase 
D) A gene for RNA polymerase 
E) Flanking direct repeats 
A) Indirect repeats at each end 
B) A gene for transposase 
C) A gene for reverse transcriptase 
D) A gene for RNA polymerase 
E) Flanking direct repeats

Question 11

During mismatch repair it is essential for the cell to be able to distinguish between the old template DNA strand and the newly synthesized DNA strand in order to make the appropriate correction of a mispairing created during DNA replication.How is this accomplished in E.coli?

Accepted Answer

In E.coli, adenosines at GATC sites are

Question 12

A transposable element is found to use RNA as an intermediate in transposition.On the basis of this information, which of the following would you expect to be CORRECT?

Accepted Answer

A) The transposable element also probably makes transposase. 
B) The transposable element may encode a reverse transcriptase. 
C) The transposable element is probably located in a bacterial genome. 
D) The transposable element probably contains inverted repeats at each end. 
E) The transposable element will not be able to transpose without a second copy also present in the genome. 
A) The transposable element also probably makes transposase. 
B) The transposable element may encode a reverse transcriptase. 
C) The transposable element is probably located in a bacterial genome. 
D) The transposable element probably contains inverted repeats at each end. 
E) The transposable element will not be able to transpose without a second copy also present in the genome.

Question 13

Huntington disease can strike at an earlier age and bring about a more rapid degeneration and death in successive generations within a family.This phenomenon can be explained by which mechanism?

Accepted Answer

A) Presence of a transposable element in the gene 
B) Chronic exposure to mutagens in the environment 
C) Expansion of a trinucleotide repeat in the coding sequence of the gene 
D) Presence of an extra chromosome in the germ line 
E) Absence of a gene product that is involved in DNA repair 
A) Presence of a transposable element in the gene 
B) Chronic exposure to mutagens in the environment 
C) Expansion of a trinucleotide repeat in the coding sequence of the gene 
D) Presence of an extra chromosome in the germ line 
E) Absence of a gene product that is involved in DNA repair

Question 14

What do alkylating agents do?

Accepted Answer

A) They cause pyrimidine dimers. 
B) They add methyl or ethyl groups to bases. 
C) They oxidize guanine. 
D) They deaminate cytosine. 
E) All of the answers are correct. 
A) They cause pyrimidine dimers. 
B) They add methyl or ethyl groups to bases. 
C) They oxidize guanine. 
D) They deaminate cytosine. 
E) All of the answers are correct.

Question 15

Strains of E.coli that are defective in mismatch repair have very high levels of spontaneous mutagenesis.Studies have shown that in wild-type strains, A:C and G:T mispairings (as opposed to the normal A:T and G:C pairings)that occur during DNA replication are more likely than other mispairings (A:G, etc.)to be detected and.Which of the following types of base substitutions would you expect to be MOST common among the spectrum of spontaneous mutations created by the mutant mismatch repair-defective strains?

Accepted Answer

A) A-to-C 
B) C-to-A 
C) G-to-C 
D) A-to-G 
E) A-to-T 
A) A-to-C 
B) C-to-A 
C) G-to-C 
D) A-to-G 
E) A-to-T

Question 16

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 result in mutant gametes, while somatic mutations do not. 
D) Germ-line mutations are reversible, while somatic mutations are not. 
E) Germ-line mutations result in cancers, while somatic mutations do not. 
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 result in mutant gametes, while somatic mutations do not. 
D) Germ-line mutations are reversible, while somatic mutations are not. 
E) Germ-line mutations result in cancers, while somatic mutations do not.

What is the function of DNA glycosylases?

What is the difference between a missense mutation and a nonsense mutation?

The mutation shown in the diagram below can best be described as a _____ mutation.

Why do disruptive DNA lesions, like deletions and insertions, sometimes not lead to frameshift mutations?

In the Ames test, what types of mutations are used to test for chemical mutagens?

Fragile-X syndrome is an example of a disease caused by what type of mutation?

Practically all transposable elements that have been studied are associated with which of the following?

During mismatch repair it is essential for the cell to be able to distinguish between the old template DNA strand and the newly synthesized DNA strand in order to make the appropriate correction of a mispairing created during DNA replication.How is this accomplished in E.coli?

A transposable element is found to use RNA as an intermediate in transposition.On the basis of this information, which of the following would you expect to be CORRECT?

Huntington disease can strike at an earlier age and bring about a more rapid degeneration and death in successive generations within a family.This phenomenon can be explained by which mechanism?

What do alkylating agents do?

How do germ-line mutations differ from somatic mutations?

Introduction to Genetics

Chromosomes and Cellular Reproduction

Basic Principles of Heredity

Sex Determination and Sex-Linked Characteristics

Linkage, Recombination, and Eukaryotic Gene Mapping

Chromosome Variation

Bacterial and Viral Genetic Systems

DNA- the Chemical Nature of the Gene

DNA Replication and Recombination

From DNA to Proteins- Transcription and Rna Processing

From DNA to Protein- Translation

Control of Gene Expression

Molecular Genetic Analysis and Biotechnology

Genomics and Proteomics

Cancer Genetics

Quantitative Genetics

Population and Evolutionary Genetics

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Exam 13: Gene Mutations, Transposable Elements, and Dna Repair

What is the function of DNA glycosylases?

What is the difference between a missense mutation and a nonsense mutation?

The mutation shown in the diagram below can best be described as a _____ mutation.

Why do disruptive DNA lesions, like deletions and insertions, sometimes not lead to frameshift mutations?

In the Ames test, what types of mutations are used to test for chemical mutagens?

Fragile-X syndrome is an example of a disease caused by what type of mutation?

Practically all transposable elements that have been studied are associated with which of the following?

During mismatch repair it is essential for the cell to be able to distinguish between the old template DNA strand and the newly synthesized DNA strand in order to make the appropriate correction of a mispairing created during DNA replication.How is this accomplished in E.coli?

A transposable element is found to use RNA as an intermediate in transposition.On the basis of this information, which of the following would you expect to be CORRECT?

Huntington disease can strike at an earlier age and bring about a more rapid degeneration and death in successive generations within a family.This phenomenon can be explained by which mechanism?

What do alkylating agents do?

How do germ-line mutations differ from somatic mutations?

Introduction to Genetics

Chromosomes and Cellular Reproduction

Basic Principles of Heredity

Sex Determination and Sex-Linked Characteristics

Linkage, Recombination, and Eukaryotic Gene Mapping

Chromosome Variation

Bacterial and Viral Genetic Systems

DNA- the Chemical Nature of the Gene

DNA Replication and Recombination

From DNA to Proteins- Transcription and Rna Processing

From DNA to Protein- Translation

Control of Gene Expression

Molecular Genetic Analysis and Biotechnology

Genomics and Proteomics

Cancer Genetics

Quantitative Genetics

Population and Evolutionary Genetics

Filters