Bios Exam 3 Chapter 14 – Flashcards

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question
A chemical agent that interferes with DNA repair may be considered a mutagen.
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True
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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.
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B
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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
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C & D
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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.
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E
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A nonsense mutation:
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changes a codon for an amino acid into a codon for chain termination.
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Deletions that eliminate a multiple of three nucleotides can:
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delete amino acids in a polypeptide chain.
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The human genome contains a family of genes that code for different forms of myosin. How could this gene family have arisen?
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The original myosin gene was duplicated, and the resulting copies have diverged.
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The enzyme _____ repairs 99% of mismatched bases immediately during replication.
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DNA Polymerase
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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.
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E
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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.
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C
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The most frequent kind of mutation, a point mutation, occurs when:
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DNA repair mechanisms fail. a single base pair is replaced by another.
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The process of gene duplication and divergence refers to:
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the creation of gene families, which are similar genes within a species. creating new genes by mutation in duplicates of old genes.
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Insertions and deletions of single nucleotides:
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cause frameshift mutations
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The enzyme _____ repairs breaks in the DNA sugar-phosphate backbone.
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DNA Ligase
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A family can share a genetic risk of developing cancer if:
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a germ-line mutation in one of the genes implicated in the cancer occurred in an ancestor.
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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
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D
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In the standard genetic code, how many codons for amino acids allow synonymous mutations in the third position?
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59
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A point mutation that causes an amino acid replacement is called a:
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nonsynonymous (missense) mutation
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A point mutation that creates a premature stop codon is called a _____ mutation.
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nonsense
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Which of the following types of mutation is typically harmful? A: gene duplication B: deletion of the centromere C: reciprocal translocation D: gene inversion
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B
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Chromosomes in which the normal order of a block of genes is reversed contain a(n):
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inversion
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A chromosomal mutation in which a segment is missing is called a deletion.
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True
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Point mutations that cause amino acid replacements are called:
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nonsynonymous (missense) mutation
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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?
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3′-CTC-5′/5′-GAG-3′' to 3′-CAC-5′/5′-GTG-3′
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Some people with blue eyes have a small sector of one eye that is brown. What kind of mutation could cause this color difference?
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a somatic mutation late in development
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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?
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no; no
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Why do RNA viruses and retroviruses have such high rates of mutation?
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because RNA is more fragile than DNA and is therefore more likely to be damaged because viral polymerases lack a proofreading mechanism
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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:
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duplication and divergence.
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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?
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translocation
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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?
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reciprocal translocation
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Only germ-line mutations are transmitted to the progeny.
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True
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When nonhomologous chromosomes exchange parts, a(n) _____ has occurred.
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reciprocal translocation
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_____ mutations are important to the evolutionary process; most cancers result from _____ mutations.
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Germline; Somatic
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Large chromosomal inversions can cause problems in which of the following processes?
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meiosis
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Any heritable change in the genetic material is _____.
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a mutation
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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?
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missense
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. 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
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A
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The relatively large number of new mutations that occur in the human genome in each generation is tolerable because:
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most of our genome is noncoding DNA, so few mutations affect our proteins.
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_____ is the process where new genes evolve from duplicates of old ones.
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Duplication and divergence
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Point mutations can impair a protein if they result in a:
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nonsense codon. shift in reading frame. nonsynonymous codon.
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A point mutation that causes no change in the amino acid sequence of a protein is called a:
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synonymous (silent) mutation
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An agent that increases mutation rate is a _____.
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mutagen
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Sickle-cell anemia results from what type of mutation?
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missense
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Movable DNA sequences are called:
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transposable elements.
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Cancer is usually due to:
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a series of mutations that occur in a single lineage of somatic cells.
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Why do data on observable mutant phenotypes underestimate the actual frequency of mutation?
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Many mutations are in noncoding regions of the genome. Some mutations in protein-coding regions of the genome are synonymous mutations.
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