Bios Exam 3 Chapter 14

A chemical agent that interferes with DNA repair may be considered a mutagen.True
Which of the following statements concerning cancer and mutations is CORRECT?

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

B
Which of the following point mutations is unlikely to change a protein’s ability to function? (Select all that apply.)

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

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

E
A nonsense mutation:changes a codon for an amino acid into a codon for chain termination.
Deletions that eliminate a multiple of three nucleotides can:delete amino acids in a polypeptide chain.
The human genome contains a family of genes that code for different forms of myosin. How could this gene family have arisen?The original myosin gene was duplicated, and the resulting copies have diverged.
The enzyme _____ repairs 99% of mismatched bases immediately during replication.DNA Polymerase
Which of the following statements applies to frameshift mutations?

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

E
Which of the following statements MOST accurately describes the benefits of the proofreading function of DNA polymerase?

A: DNA polymerase can be recruited to recently mutated sites to repair mutations.
B: DNA polymerase is always present in the nucleus and can repair all mutations when they occur.
C: DNA polymerase can repair most mutations as they occur during DNA replication.
D: All DNA mutations can be detected and repaired during DNA replication.

C
The most frequent kind of mutation, a point mutation, occurs when:DNA repair mechanisms fail.

a single base pair is replaced by another.

The process of gene duplication and divergence refers to:the creation of gene families, which are similar genes within a species.

creating new genes by mutation in duplicates of old genes.

Insertions and deletions of single nucleotides:cause frameshift mutations
The enzyme _____ repairs breaks in the DNA sugar-phosphate backbone.DNA Ligase
A family can share a genetic risk of developing cancer if:a germ-line mutation in one of the genes implicated in the cancer occurred in an ancestor.
Which of the following causes breaks in one or both of the sugar-phosphate backbones?

A: tobacco smoke
B: UV radiation
C: exposure to oxidizing agents such as household bleach or hydrogen peroxide
D: X-rays

D
In the standard genetic code, how many codons for amino acids allow synonymous mutations in the third position?59
A point mutation that causes an amino acid replacement is called a:nonsynonymous (missense) mutation
A point mutation that creates a premature stop codon is called a _____ mutation.nonsense
Which of the following types of mutation is typically harmful?

A: gene duplication
B: deletion of the centromere
C: reciprocal translocation
D: gene inversion

B
Chromosomes in which the normal order of a block of genes is reversed contain a(n):inversion
A chromosomal mutation in which a segment is missing is called a deletion.True
Point mutations that cause amino acid replacements are called:nonsynonymous (missense) mutation
In the sickle-cell anemia mutation, the 5′-GAG-3′ codon for glutamic acid becomes the 5′-GUG-3′ codon for valine. Assuming a single nucleotide substitution accounts for this mutation, what is the change in the DNA?3′-CTC-5′/5′-GAG-3′’ to 3′-CAC-5′/5′-GTG-3′
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 somatic mutation late in development
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?no; no
Why do RNA viruses and retroviruses have such high rates of mutation?because RNA is more fragile than DNA and is therefore more likely to be damaged

because viral polymerases lack a proofreading mechanism

You are working in a lab and studying a gene. You notice that many other genes in the same organism code for similar proteins. This is MOST likely the result of:duplication and divergence.
Normally, in corn, genes for waxy and virescent kernel appearance are in the same chromosome. In a certain stock, however, it was found that these two genes are in different chromosomes. Which chromosomal aberration would explain this?translocation
Chronic myelogenous leukemia (CML) is caused when a segment of chromosome 9 and a segment of chromosome 22 both break off and switch places. How is this mutation classified?reciprocal translocation
Only germ-line mutations are transmitted to the progeny.True
When nonhomologous chromosomes exchange parts, a(n) _____ has occurred.reciprocal translocation
_____ mutations are important to the evolutionary process; most cancers result from _____ mutations.Germline; Somatic
Large chromosomal inversions can cause problems in which of the following processes?meiosis
Any heritable change in the genetic material is _____.a mutation
Imagine a gene in which the sequence that is transcribed into a GAG codon, which codes for glutamic acid, is mutated to GUG, which codes for valine. What type of mutation is this?missense
. 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: All of these choices are correct.
B: exposure to chemical mutagens
C: mutations in a melanocyte
D: exposure to solar radiation

A
The relatively large number of new mutations that occur in the human genome in each generation is tolerable because:most of our genome is noncoding DNA, so few mutations affect our proteins.
_____ is the process where new genes evolve from duplicates of old ones.Duplication and divergence
Point mutations can impair a protein if they result in a:nonsense codon.

shift in reading frame.

nonsynonymous codon.

A point mutation that causes no change in the amino acid sequence of a protein is called a:synonymous (silent) mutation
An agent that increases mutation rate is a _____.mutagen
Sickle-cell anemia results from what type of mutation?missense
Movable DNA sequences are called:transposable elements.
Cancer is usually due to:a series of mutations that occur in a single lineage of somatic cells.
Why do data on observable mutant phenotypes underestimate the actual frequency of mutation?Many mutations are in noncoding regions of the genome.

Some mutations in protein-coding regions of the genome are synonymous mutations.