Deck 14: Mutation and Dna Repair

Question 1

The American Cancer Society currently estimates that only about 10% of all people with melanoma have a family history of the disease. What factors might contribute to the development of melanoma in the other 90% of patients?

A)exposure to solar radiation
B)mutations in a melanocyte
C)exposure to chemical mutagens
D)All of these choices are correct.

Answer 1

D

Question 2

A family can share a genetic risk of developing cancer if:

A)the cancer is caused by somatic cell mutations.
B)the cancer is caused by germ-line mutations.
C)a germ-line mutation in one of the genes implicated in the cancer occurred in an ancestor.
D)a somatic cell mutation in one of the genes implicated in the cancer occurred in an ancestor.
E)All of these choices are correct.

Answer 2

C

Question 3

The definition of mutation is "any heritable change in the genetic material." The qualifier "heritable" is necessary because:

A)most changes in the genetic material are harmful to the organism.
B)changes in the genetic material occur at random along the genome.
C)changes in the genetic material occur without regard to the needs of the organism.
D)most changes in the genetic material are repaired soon after they occur.

Answer 3

D

Question 4

Why do data on observable mutant phenotypes underestimate the actual frequency of mutation?

A)Many mutations are in noncoding regions of the genome.
B)Some mutations in protein-coding regions of the genome are synonymous mutations.
C)Most mutations result in death of the individual or an inability to reproduce.

Question 5

Any mutation that increases the risk of disease in an individual is known as a:

A)transmission mutation.
B)somatic mutation.
C)genetic load.
D)genetic risk factor.
E)predisposition factor.

Question 6

If an organism is treated with a dose of radiation that quadruples the rate of mutation observed in the absence of radiation and a mutation subsequently occurs, what is the probability that it was caused by the chemical agent?

A)0
B)1/4
C)1/2
D)3/4
E)1)0

Question 7

In living organisms, on average, about one nucleotide in every _____ is mistakenly substituted for another during each round of DNA replication.

A)100
B)1000
C)100,000
D)1 billion
E)10 billion

Question 8

According to Figure 14.2, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes.

A)2
B)10
C)100
D)1000
E)10,000

Question 9

Melanoma is cancer of the skin that originates with uncontrolled division of a melanocyte (pigment cell). Although genetic tests are available to screen for melanoma, they are not appropriate for all individuals. However, an individual's risk can be assessed by analyzing his or her family history. An individual's risk of developing melanoma increases if one or more first-degree relative (mother, father, brother, sister, child) has had melanoma. Which of the following are possible explanations for this increased risk?

A)inheritance of any gene mutation that predisposes the individual to developing any type of cancer
B)inheritance of specific gene mutations that predisposes the individual to developing melanoma
C)similarity in lifestyles among individuals of the same family line (e.g., use of tanning beds or time outside in the sun)
D)the high likelihood of multiple family members who develop identical somatic cell mutations later in life

Question 10

Why do mutations associated with cancer almost always occur sequentially instead of simultaneously?

A)The mutations are extremely unlikely to occur in the same cell at the same time.
B)Each mutation increases cellular growth rate, allowing more cells to have a higher chance of the next mutation.
C)Each mutation adds to the growth advantage of the ones occurring previously.
D)All of these choices are correct.

Question 11

In bacteria, there is a distinction between somatic cell and germ line mutations.

Question 12

The enzyme _____ repairs breaks in the DNA sugar-phosphate backbone.

A)DNA ligase
B)DNA polymerase
C)AP endonuclease
D)uracyl glycosylase
E)None of the other answer options is correct.

Question 13

Which of the curves shown here BEST represents current understanding of the rate of mutation in human sperm as the father's age increases from 20 to 40?

A)curve M
B)curve H
C)curve K
D)curve L
E)curve Q

Question 14

In many organisms, mutations that replace one pyrimidine with another, or one purine with another, are more frequent than mutations that replace a pyrimidine with a purine or vice versa. What does this finding imply about the accuracy of the statement "mutations are random."

A)The statement applies to all types of mutations, regardless of their chemistry.
B)The statement applies only to single-nucleotide point mutations.
C)The statement applies only to single-nucleotide frameshift mutations.
D)The statement applies only to nucleotide changes that result in nonsense codons.
E)"Random" means without regard for the needs of the organism.

Question 15

It has been estimated that the average human gamete contains about 30 new nucleotide-substitution mutations and approximately 3 new small insertions or deletions (indels). Which of the following is/are TRUE?

A)The estimate must be wrong. Nobody could live with so many mutations.
B)Many of the mutations are likely to be in nonprotein coding DNA.
C)Most of the mutations have little or no effect on survival or health.
D)None of the other answer options is correct.

Question 16

If an organism is treated with a chemical agent that doubles the rate of mutation observed in its absence, and a mutation occurs, what is the probability that it was caused by the chemical agent?

A)0
B)1/4
C)1/2
D)3/4

Question 17

In flowering plants, somatic tissue can differentiate into the sexual organs. This means that:

A)all somatic mutations in plants can affect future generations.
B)some somatic mutations in plants can affect future generations.
C)no somatic mutations in plants can affect future generations.
D)the DNA repair mechanisms in plants are much more efficient than those in animals.

Question 18

In the standard genetic code (Table 4.1, shown below), how many codons for amino acids allow synonymous mutations in the third position?

A)19
B)29
C)39
D)49
E)59

Question 19

It has been estimated that the average human gamete contains about 30 new nucleotide-substitution mutations and approximately 3 new small insertions or deletions (indels). Assuming a human genome size of 3 × 10⁹ base pairs, what is the estimated rate of nucleotide-substitution mutations and of indel mutations per nucleotide pair per generation?

A)10^-6; 10^-7
B)10^-7; 10^-8
C)10^-8; 10^-9
D)10^-9; 10^-10

Question 20

Some people with blue eyes have a small sector of one eye that is brown. What kind of mutation could cause this color difference?

A)a somatic mutation in germ-line cells
B)a somatic mutation very early in development
C)a somatic mutation late in development
D)a germ-line mutation

Question 21

Only germ-line mutations are transmitted to the progeny.

Question 22

Sites in the genome that are more susceptible to mutations than others are called:

A)mutation spots.
B)hotspots.
C)risk factors.
D)genes.
E)noncoding DNA.

Question 23

_____ mutations are important to the evolutionary process; most cancers result from _____ mutations.

A)Somatic; germ-line
B)Germ-line; somatic
C)Germ-line; heritable
D)Somatic; heritable
E)Point; germ-line

Question 24

In humans, the rate of point mutation tends to be greater in males than in females because:

A)the testes are more exposed to the environment than the ovaries.
B)male meiosis is more sensitive to mutagens than female meiosis.
C)DNA repair in males is less efficient than that in females.
D)male germ-line cells undergo many more divisions than female germ-line cells.

Question 25

A population of mosquitoes is exposed to the pesticide DDT for several generations. At the end of that time, most individuals in the population are resistant to DDT. The MOST likely reason is that:

A)DDT caused the mutations that led to resistance.
B)Some individuals in the original population had the mutations that led to resistance.
C)By chance, new mutations that led to DDT resistance arose after DDT was used.
D)Somatic mutations in the original population were passed on to subsequent generations.
E)Random mutations in each generation made mosquitoes resistant to DDT.

Question 26

Spontaneous mutations that occur in somatic cells will be transmitted to offspring.

Question 27

Which mutations in an animal somatic cell would be inherited by the next generation?

A)point mutations
B)synonymous mutations
C)deletions
D)None of the other answer options is correct.

Question 28

_____ mutations affect only the individual in which they occur; _____ mutations are passed from parent to offspring.

A)Somatic; germ-line
B)Germ-line; somatic
C)Germ-line; heritable
D)Somatic; point
E)Point; germ-line

Question 29

Any heritable change in the genetic material is a _____.

Question 30

Why do RNA viruses and retroviruses have such high rates of mutation?

A)because RNA polymerase is an unstable enzyme
B)because RNA viruses and retroviruses initially cause host-cell mutations during replication
C)because RNA is more fragile than DNA and is therefore more likely to be damaged
D)because viral polymerases lack a proofreading mechanism
E)because viral RNA can form stem-and-loop structures

Question 31

Genetic risk factors:

A)can increase the likelihood of diseases.
B)include mutations in the BRCA1 and BRCA2 genes.
C)can work synergistically with environmental risk factors.
D)can be heritable.
E)All of these choices are correct.

Question 32

Mutation rates (per nucleotide per replication) are:

A)higher in organisms with larger genomes.
B)similar across all organisms.
C)highest in viruses.
D)lower in organisms with larger genomes.
E)highest in bacteria.

Question 33

The relatively large number of new mutations that occur in the human genome in each generation is tolerable because:

A)we have excellent DNA repair mechanisms.
B)most of the mutations occur in somatic cells, not germ cells.
C)most of our genome is noncoding DNA, so few mutations affect our proteins.
D)we have excellent protein repair mechanisms.
E)compared to other organisms, changes in our proteins have relatively little effect on our cells' structures and functions.

Question 34

The use of antibiotics creates mutations in bacteria that make the bacteria resistant to these antibiotics.

Question 35

Even though the chance of a mutation for one given nucleotide is rare, mutations are rather common when looking at the whole genome.

Question 36

Mutations will always decrease the activity of a gene.

Question 37

Which of the following statements MOST accurately explains why the average rate of mutation in humans does not accurately describe the pattern of mutations across the genome?

A)Some sites in the genome (hotspots)are more mutable than others.
B)Mutation rates differ between males and females.
C)Mutation rates differ between germ-line cells and somatic cells.
D)Mutation rates vary with age.
E)None of the answer options is correct.

Question 38

In an RNA molecule with a random sequence of nucleotides, what is the probability that any three adjacent nucleotides have the sequence AUG? What is the average number of nucleotides between successive occurrences of AUG?

A)1/8; 8
B)1/16; 16
C)1/48; 48
D)1/64; 64
E)None of the answer options is correct.

Question 39

Beneficial mutations are those that increase survival or reproduction in the prevailing environment.

Question 40

The fact that humans have a relatively large number of mutations per genome per generation when compared with other organisms can be explained by which of the following statements?

A)Humans are so complex because we have multiple proteins doing the same job.
B)Human cells don't divide as often as those of other organisms.
C)Most of a human's DNA is noncoding, so most of the mutations are neutral.
D)Most of these mutations happen after reproduction, so they wouldn't be selected against.
E)Humans have multiple proteins doing the same job, and our cells don't divide as often as other those of other organisms.

Question 41

Which of the following point mutations is unlikely to change a protein's ability to function?

A)one that occurs in a noncoding region of DNA
B)one that creates a new codon code for the same amino acid as the original codon
C)one that occurs in somatic cells
D)one that creates a new codon that codes for an amino acid of the same size as that coded for by the original codon
E)one that occurs in germ cells

Question 42

In the standard genetic code (Table 4.1, shown below), how many amino acids have codons that allow synonymous mutations in the second position?

A)0
B)2
C)8
D)16
E)20

Question 43

In the procedure of replica plating, the purpose of the sterilized velvet is to:

A)protect the agar plates from bacteria in the air.
B)protect the researchers from coming into contact with the bacteria.
C)transfer bacterial cells from one agar plate to another.
D)induce new mutations that can grow on the selective plates.

Question 44

Consider the single methionine codon 5-AUG-3 in the standard genetic code. Can a single base change in this codon create a synonymous mutation? Can a single base change in this codon create a stop codon?

A)yes; yes
B)yes; no
C)no; yes
D)no; no

Question 45

In the standard genetic code (Table 4.1, shown below), a nucleotide in a codon is said to be a fourfold degenerate site if its mutation to any other nucleotide results in a synonymous mutation. How many codons in the standard genetic code have a fourfold degenerate site?

A)4
B)8
C)12
D)16
E)20

Question 46

Consider the tryptophan codon 5-UGG-3 in the standard genetic code (Table 4.1, shown below). Can a single base change in this codon create a synonymous mutation? Can a single base change in this codon create a nonsense codon?

A)yes; yes
B)yes; no
C)no; yes
D)no; no

Question 47

Which of the following statements concerning cancer and mutations is CORRECT?

A)Cancer can only occur with a mutation in a somatic cell.
B)Cancer can only occur with a mutation in a germ cell.
C)Usually, multiple mutations are required in different genes to cause cancer.
D)Usually, a single mutation is all that is required to cause cancer.
E)None of the other answer options is correct.

Question 48

You have identified two different mutations that inactivate the same gene. One is a point mutation (a single nucleotide substitution), and the other is a deletion. Which of the following statements is TRUE?

A)The deletion will have a more severe effect than the point mutation.
B)The point mutation can be reversed by another point mutation, but the deletion cannot.
C)If the point mutation is heterozygous, the deletion is likely to be homozygous.
D)The deletion, but not the point mutation, will be visible through a light microscope.

Question 49

Which of the following statements is TRUE concerning the work of the Esther and Joshua Lederberg?

A)Their work demonstrated that mutations in organisms arise in response to environmental conditions.
B)Their work demonstrated that mutations are determined by an organism's "needs."
C)Their work demonstrated that mutations cannot occur randomly in organisms.
D)Their work relied on a technique of bacterial culture known as "replica plating."
E)Their work relied on a technique of bacterial culture known as "replica plating," and demonstrated that mutations occur randomly in organisms.

Question 50

In the standard genetic code (Table 4.1, shown below), what fraction of codons are nonsense codons?

A)1/64
B)2/64
C)3/64
D)4/64
E)5/64

Question 51

Replica plating showed that mutations for antibiotic resistance are NOT induced by the presence of the antibiotic because antibiotic-resistant cells:

A)occur in colonies that never experienced the antibiotic.
B)are able to form colonies in the absence of the antibiotic.
C)are able to form colonies in the presence of the antibiotic.
D)are unable to form colonies in the presence of the antibiotic.

Question 52

Which of the following statements applies to frameshift mutations?

A)They cause the insertion or deletion of a single amino acid from the polypeptide chain.
B)They create a premature stop codon at the site of mutation.
C)They change the amino acid sequence downstream from the mutant site.
D)They are known risk factors in most forms of cancer, including breast and colon cancer.
E)They are known risk factors in breast cancer, but not colon cancer.

Question 53

In bacteria, many transposable elements are able to regulate their own transposition in such a way that the probability of transposition decreases as the number of copies of the transposon in a cell increases. If a transposon invades a bacterial cell that does not currently have any transposons, and then increases in copy number as the cell divides, what curve below would BEST depict the increase in copy number of such a self-regulating transposon?

A)curve M
B)curve H
C)curve K
D)curve L
E)curve Q

Question 54

Deletions that eliminate a multiple of three nucleotides can:

A)cause nonsense mutations in an open reading frame.
B)cause frameshift mutations in an open reading frame.
C)delete amino acids in a polypeptide chain.
D)shorten chromosomes from the telomeres inward.
E)cause cancer in a subset of somatic cells.

Question 55

The procedure of replica plating demonstrated that mutations are random with respect to:

A)point mutations or deletions.
B)whether A or G is replaced with T or C.
C)germ-line cells or somatic cells.
D)the needs of the organism.
E)All of these choices are correct.

Question 56

The number of new mutations in organisms following a round of genome replication:

A)generally increases with larger genomes.
B)generally decreases with larger genomes.
C)is similar, independent of genome size.
D)is highest in bacteria.
E)None of the answer options is correct.

Question 57

A mutation consisting of a single-nucleotide deletion creates a frameshift in a long open reading frame. In the shifted reading frame, what is the expected average number of codons before a nonsense codon is encountered? (Round any fraction to the nearest whole number.)

A)11
B)13
C)16
D)21
E)32

Question 58

Which of the following would you expect to have the lowest rate of point mutations per replication?

A)bacteria
B)DNA viruses
C)RNA viruses
D)fruit flies
E)humans

Question 59

A loss-of-function mutation is one in which the function of a gene is completely knocked out or obliterated. Which of the following mutations results in the loss of function of one or more genes?

A)deletion
B)duplication
C)translocation
D)inversion
E)frameshift

Question 60

In the standard genetic code, how many amino acids have codons that allow synonymous mutations in the first position?

A)0
B)2
C)8
D)16
E)20

Question 61

Movable DNA sequences are called:

A)transposable elements.
B)frameshifts.
C)transition elements.
D)centromeres.
E)telomeric elements.

Question 62

Which of the following is MOST likely to result in a nonfunctional polypeptide?

A)a silent mutation
B)a missense mutation
C)a nonsense mutation
D)a transition mutation
E)Silent and missense mutations are the most likely to result in a nonfunctional polypeptide.

Question 63

In a muscle cell, myosin binds to actin to cause muscle contraction. Researchers have found that rabbit muscle myosin binds to actin from an amoeba. How can this be?

A)The myosin from amoeba and rabbits is similar due to a distant common ancestor.
B)The differences in myosin between amoeba and rabbits do not affect the actin-binding site of myosin.
C)Proteins whose functions are important to many types of organisms are more likely to be conserved.
D)The myosin from amoeba and rabbits is similar due to a distant common ancestor, and the differences between them do not affect the actin binding site.
E)All of these choices are correct.

Question 64

A point mutation that causes an amino acid replacement is called a:

A)synonymous (silent)mutation.
B)nonsynonymous (missense)mutation.
C)nonsense mutation.
D)stop mutation.
E)transition mutation.

Question 65

What is the minimum number of single-nucleotide substitutions that would be necessary for each of the following amino acid replacements: PheVal; TyrGly; MetPro; ArgCys?

A)1; 1; 2; 3
B)1; 2; 2; 1
C)2; 3; 1; 1
D)2; 2; 3; 3
E)2; 2; 1; 1

Question 66

Cancer is usually due to:

A)exposure to chemicals or radiation.
B)mutations in stem cells.
C)a series of mutations that occur throughout an affected tissue or organ.
D)a series of mutations that occur in a single lineage of somatic cells.
E)a series of mutations that occur in multiple lineages of germ-line cells.

Question 67

The most frequent kind of mutation, a point mutation, occurs when:

A)a single base pair is replaced by another.
B)DNA repair mechanisms fail.
C)open reading frames are altered.
D)a block of nucleotides is rearranged.
E)None of the other answer options is correct.

Question 68

A point mutation that creates a premature stop codon is called a _____ mutation.

A)synonymous (silent)
B)nonsynonymous (missense)
C)nonsense
D)translation
E)transition

Question 69

Point mutations can impair a protein if they result in a:

A)synonymous codon.
B)nonsense codon.
C)nonsynonymous codon.
D)shift in reading frame.

Question 70

A point mutation that causes no change in the amino acid sequence of a protein is called a:

A)synonymous (silent)mutation.
B)nonsynonymous (missense)mutation.
C)nonsense mutation.
D)stop mutation.
E)transition mutation.

Question 71

Transposons can:

A)interfere with transcription.
B)cause a frameshift.
C)cause errors in mRNA processing.
D)All of these choices are correct.

Question 72

Which of the following statements about mutations is TRUE? A mutation:

A)may leave the amino acid sequence of a protein unchanged.
B)will result in a different phenotype.
C)will be corrected.
D)will be passed onto offspring.
E)None of the other answer options is correct.

Question 73

Any DNA "damage" is considered to be a mutation, even if it is immediately corrected by the action of DNA polymerase.

Question 74

The effect of an insertion or deletion of a small number of nucleotides depends on:

A)whether it occurs in a coding region or noncoding region of the DNA.
B)its size.
C)whether it occurs in a germ-line cell or somatic cell.
D)whether it involves purine or pyrimidine bases.
E)where it occurs on a chromosome.

Question 75

A nonsense mutation:

A)changes the identity of one amino acid in a polypeptide chain.
B)shifts the reading frame of a messenger RNA.
C)is usually due to a nucleotide substitution in the third position of a codon.
D)changes a codon for an amino acid into a codon for chain termination.

Question 76

When a transposable element inserts into a gene, it can:

A)interfere with transcription.
B)cause errors in RNA processing.
C)disrupt the open reading frame.
D)cause the gene to duplicate itself.
E)cause the gene to delete itself.

Question 77

Insertions and deletions of single nucleotides:

A)cause missense mutations.
B)cause frameshift mutations.
C)add or delete amino acids to or from the normal polypeptide.
D)shorten chromosomes.
E)cause cancer.

Question 78

In a genome sequence, multiple copies of a transposable element scattered throughout the genome would be annotated as a(n):

A)direct repeat.
B)inverted repeat.
C)tandem repeat.
D)privileged repeat.
E)dispersed repeat.

Question 79

A point mutation occurs when a single nucleotide gets replaced by a different one.

Question 80

How could you create long, synthetic RNA with a random sequence of ribonucleotides that would contain no nonsense codon?

A)leave out T
B)leave out G or C
C)leave out G
D)leave out C
E)leave out A or U