Deck 7: Dna Mutation, DNA Repair, and Transposable Elements

Question 1

Which of the following transposable elements are found in eukaryotes but not in prokaryotes?

A)IS elements
B)Families of autonomous and nonautonomous elements
C)Retrotransposons
D)Ty elements
E)B,C,and D only

Answer 1

E

Question 2

A mutation during DNA replication causes a G to be inserted after the first base of the codon for tryptophan.How will this affect the growing polypeptide chain?

A)It will not be affected.
B)Elongation will stop prematurely.
C)There will be a single amino acid substitution.
D)The reading frame will be shifted to the left,and the wrong amino acids will be added from this point on.
E)An extra amino acid will be added,but the reading frame will not be affected.

Answer 2

D

Question 3

Nonsense suppressors are usually mutations in genes coding for

A)proteins.
B)enzymes.
C)mRNA.
D)tRNA.
E)rRNA.

Answer 3

D

Question 4

In order for the dissociation element (Ds)mutations in corn to be stable,

A)an Ac element must be present.
B)an Ac element must not be present.
C)the Ds must contain the gene for transposition.
D)the DNA must not be replicated.
E)None of these

Question 5

Which procedure would you use to detect a nutritional mutation in microorganisms?

A)Visible inspection
B)Replica plating
C)Controlled crosses
D)Isolation at high temperature
E)Plating on antibiotic-containing medium

Question 6

Xeroderma pigmentosum is a human genetic disease caused by

A)elevated levels of cholesterol in the blood.
B)failure to produce pigment that protects the skin cells from UV light exposure.
C)defective DNA excision-repair mechanisms.
D)mutations that inactivate tumor suppressor genes.
E)loss of genes controlling the SOS response.

Question 7

In Drosophila,the wild-type eye color is red.A mutation,vermilion,causes vermilion-colored eyes,unless there is a mutation in another gene,suv,which,when homozygous or hemizygous,results in eyes that are the wild-type red even in the presence of the vermilion mutation.This is an example of

A)forward mutation.
B)reverse mutation.
C)intragenic suppression.
D)intergenic suppression.
E)back mutation.

Question 8

Base analogs may cause mutations because

A)they modify the chemical structure and properties of the normal base.
B)they insert themselves between adjacent bases on the DNA strand and cause an extra base to be inserted during replication.
C)they remove amino groups from bases,causing them to pair with the wrong base during replication.
D)they may exist in alternate chemical states that pair with different DNA bases than the normal state during replication.
E)Both A and C

Question 9

Spontaneous mutation rates are greatly reduced by

A)exposure to ionizing radiation.
B)reverse mutations.
C)base-modifying agents.
D)DNA repair mechanisms.
E)performing the Ames test.

Question 10

A transposon is

A)a DNA segment that can insert itself at one or more sites in a genome.
B)a "jumping gene."
C)a DNA segment that may cause mutations in genes or chromosomal rearrangements.
D)a mobile genetic element that may or may not leave a copy of itself in its original site when it moves to a new site.
E)All of these

Question 11

Which of the following is not mutagenic?

A)5BU
B)AZT
C)Nitrous acid
D)Hydroxylamine
E)Acridine

Question 12

What is conservative transposition?

A)No net increase in the number of transposable elements in the genome.
B)A net increase in the number of transposable elements in the genome.
C)Movement of transposable elements with replication of the element.
D)Movement of transposable elements without replication of the element.
E)Transposition without disruption of normal gene product activity.

Question 13

Thymine dimers are commonly caused by

A)ultraviolet radiation.
B)ionizing radiation such as X-rays.
C)tautomers.
D)alkylating agents.
E)intercalating agents.

Question 14

The deamination of cytosine creates

A)5-methyl cytosine.
B)uracil.
C)2-aminopurine.
D)5-bromouracil.
E)thymine.

Question 15

An IS (insertion sequence)element contains

A)a transposase gene only.
B)a transposase gene and additional genes.
C)a transposase gene and inverted repeats at the ends.
D)a transposase gene,additional genes,and inverted repeats at the ends.
E)genes but not a transposase gene.

Question 16

Dissociation elements (Ds)in plants are examples of

A)activator transposons that can direct their own transposition.
B)nonautonomous elements that require activation by an autonomous element.
C)mutator genes that increase the spontaneous mutation frequencies of other genes.
D)repeated sequences that are targeted by a transposase.
E)Both B and C

Question 17

Which of the following nucleotide changes leads to a transition mutation?

A)Adenine to guanine
B)Adenine to cytosine
C)Guanine to cytosine
D)Thymine to guanine
E)Guanine to thymine

Question 18

Mutation frequency is the

A)number of mutations per gene per generation.
B)number of mutations per nucleotide per generation.
C)number of mutations per cell per generation.
D)number of a specific mutation in a defined population.
E)total number of mutations in a defined population.

Question 19

The codon 5'-AAA-3' codes for the amino acid lysine.Which of the following mutations in this codon is a neutral mutation?

A)5'-ATA-3' to isoleucine
B)5'-AGA-3' to arginine
C)5'-AAG-3' to lysine
D)5'-CAA-3' to glutamine
E)5'-AAC-3' to asparagine

Question 20

What kind of mutation-detection procedure can be used to detect the white-eye mutation in Drosophila?

Question 21

How can PCR be used to induce site-specific mutations in DNA?

Question 22

Composite transposons contain a central region with genes and repeated sequences at their ends but do not terminate with IS elements.

Question 23

Genetic manipulation in Drosophila may be assisted by the use of

A)P elements.
B)Ty elements.
C)factor.
D)bacteriophage Mu.
E)Tn10.

Question 24

A cointegrate is characteristic of replicative transposition.

Question 25

Changes in heritable traits result from adaptation to environmental influences.

Question 26

A tumor suppressor gene is cloned and mutagenized in vitro,then injected into mouse embryos to create knockout mice.How could you identify the heterozygous knockout mice and create mice susceptible to tumors?

Question 27

A transposon may carry genes for proteins that enable their transposition as well as genes for other functions such as drug resistance.

Question 28

An mRNA codon reads GUA.If a transition mutation occurs at the third base pair,will the final protein be changed?

Question 29

Somatic mutations may be inherited by the next generation.

Question 30

How does an intercalating agent such as ethidium bromide cause mutations?

Question 31

LINEs and SINEs are repetitive sequences in humans that can also,as retrotransposons,insert into genes and cause disease.

Question 32

A silent mutation is a change in the DNA sequence that alters the amino acid sequence of the encoded protein but does not change its function.

Question 33

A point mutation changes a codon from UCG to UAG.What will happen to the resulting polypeptide?

Question 34

5-bromouracil (5BU)is a mutagen because it is an analog of the base thymine and may pair with guanine instead of adenine if it is incorporated into a DNA strand.

Question 35

The DNA polymerase proofreading mechanism maintains a low mutation rate in eukaryotic genes.

Question 36

What are two ways that a reverse mutation can occur?

Question 37

A tautomer is an uncommon form of DNA base that naturally exists along with the common form.

Question 38

Describe how the Ames test is used to determine whether a particular chemical is mutagenic.

Question 39

For a particular gene,if one gene in a million experiences a mutation each generation,what is its mutation frequency?

Question 40

Explain how IS elements produce target-site duplications when they move.

Question 41

What is a retrotransposon,and how does it differ from typical transposons?

Question 42

Barbara McClintock discovered that a controlling element was responsible for the mutant-spotted phenotype (purple spots on white)in corn kernels.Explain how this works.

Question 43

How was the adaptive method for acquiring mutations disproved?

Question 44

Explain what a mutator gene is and give an example.

Question 45

How does the nucleotide excision repair (NER)system in E.coli work,and what kinds of DNA damage does it repair?