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.
|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
|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.
|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.
|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.
|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
|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
|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.
|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.
|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.