mutation repair
What can a transposable element do when it inserts into a gene? Select all that apply. 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
A) interfere with transcription B) cause errors in RNA processing C) disrupt the open reading frame
Large chromosomal inversions can cause problems in which of these processes? A) meiosis B) mismatch repair C) mitosis D) None of the other answer options is correct.
A) meiosis
Which type of repair is a backup for the DNA polymerase proofreading function? A) mismatch repair B) base excision repair C) nucleotide excision repair D) DNA ligase
A) mismatch repair mismatch is for errors that occurred during replication.
The enzyme _____ repairs 99% of mismatched bases immediately during DNA replication. A) DNA ligase B) DNA polymerase C) AP endonuclease D) uracyl glycosylase E) None of the other answer options is correct.
B) DNA polymerase
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.
D) All of these choices are correct.
Transposons can: A) interfere with transcription. B) cause a frameshift. C) cause errors in mRNA processing. D) All of these choices are correct.
D) All of these choices are correct.
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 the cellular growth rate, allowing more cells to have a higher chance of thenext mutation. C) Each mutation adds to the growth advantage of the ones occurring previously D) All of these choices are correct.
D) All of these choices are correct.
The enzyme _____ repairs breaks in the DNA sugar-phosphate backbone. A) uracyl glycosylase B) DNA polymerase C) AP endonuclease D) DNA ligase E) None of the other answer options is correct.
D) DNA ligase
Which of the statements most accurately describes the benefits of the proofreading function of DNA polymerase? A) All DNA mutations can be detected and repaired during DNA replication. B) DNA polymerase is always present in the nucleus and can repair all mutations when they occur. C) DNA polymerase can be recruited to recently mutated sites to repair mutations. D) DNA polymerase can repair most mutations as they occur during DNA replication.
D) DNA polymerase can repair most mutations as they occur during DNA replication.
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) 100000 D) 1 billion E) 10 billion
E) 10 billion
Incorrectly repaired double-stranded breaks in DNA can produce: A) duplications. B) deletions. C) inversions. D) translocations. E) All of these choices are correct.
E) All of these choices are correct.
In a genome sequence, multiple copies of a transposable element scattered throughout the genome are annotated as a(n): A) direct repeat. B) inverted repeat. C) tandem repeat. D) privileged repeat. E) dispersed repeat.
E) dispersed repeat.
Which of the enzymes is responsible for initiating certain types of base excision repair? a. None of the answer options are correct. b. DNA polymerase c. DNA ligase d. DNA uracil glycosylase e. AP endonuclease
d. DNA uracil glycosylase
Which of the statements about viruses is true? a. Viruses are a type of prokaryotic cell. b. Viruses are the root cause of most if not all cancers. c. Human cancers have not been associated with viruses. d. None of the other answer options is correct. e. Viruses contain multiple genes and each of these genes is an oncogene.
d. None of the other answer options is correct.
Why do RNA viruses and retroviruses have such high rates of mutation? a. RNA viruses and retroviruses initially cause host-cell mutations during replication. b. RNA polymerase is an unstable enzyme. c. RNA viruses and retroviruses do not have high mutation rates. d. Viral polymerases lack a proofreading mechanism. e. Viral RNA can form stem-and-loop structures.
d. Viral polymerases lack a proofreading mechanism.
A gene associated with promoting normal cell division is called: a. an oncogene. b. a tumor suppressor. c. a proto-oncogene or a tumor suppressor. d. a proto-oncogene.
d. a proto-oncogene.
A chromosomal mutation where a segment breaks off, flips, and then reattaches itself is called a(n): a. duplication. b. deletion. c. reciprocal translocation. d. inversion. e. translocation.
d. inversion.
Cell division is regulated by: a. All of these choices are correct. b. signals that indicate that the cell has reached a sufficient size. c. growth factor signals. d. signals about the nutritional status of the cell. e. signals that indicate that DNA has been replicated.
a. All of these choices are correct.
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.
a. synonymous (silent) mutation.
Chromosomal mutations that are most likely to cause serious damage to an organism are those that affect the: A) centromere. B) telomere. C) long arm of the chromosome. D) short arm of the chromosome. E) None of the other answer options is correct.
A) centromere.
In general which is less harmful, a duplication or a deletion? A) duplication B) deletion
A) duplication
If a covalent bond joining adjacent nucleotides in a DNA strand is broken, the break could be repaired by: A) DNA ligase. B) AP endonuclease. C) DNA uracil glycosylase. D) DNA exonuclease.
A) DNA ligase.
Why do data on observable mutant phenotypes underestimate the actual frequency of mutation? Select all that apply. 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. D) The data on observable mutant phenotypes are accurate.
A) Many mutations are in noncoding regions of the genome. B) Some mutations in protein-coding regions of the genome are synonymous mutations.
The human genome contains a family of genes that code for different forms of myosin. How could this gene family have arisen? A) The original myosin gene was duplicated and the resulting copies have diverged. B) Two different original genes accumulated mutations and both evolved into myosin. C) The original myosin gene was duplicated without divergence. D) The genes were transferred from a bacterium as a result of infection.
A) The original myosin gene was duplicated and the resulting copies have diverged.
Which kind of damage to DNA can be caused by X-rays? A) breaks in one or both of the sugar-phosphate backbones B) cross-links between adjacent pyrimidine bases C) addition of bulky side groups that hinder proper base pairing D) loss of a base from one of the deoxyribose sugars resulting in a gap in one DNA strand
A) breaks in one or both of the sugar-phosphate backbones
A mutation in the BRCA1 gene is associated with which disease? A) breast cancer B) retinal cancer C) bone cancer D) colon cancer
A) breast cancer
Which of the point mutations is unlikely to change a protein's ability to function? Select all that apply. 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 does not code for any amino acid E) one that occurs in germ cells
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
Beneficial mutations can: Select all that apply. A) protect from disease. B) never be reversed. C) permit an organism to become adapted to its environment. D) None of the other answer options is correct.
A) protect from disease. C) permit an organism to become adapted to its environment.
A double-stranded DNA break is harder to repair than a single-stranded DNA break. A) true B) false
A) true
Beneficial mutations are those that increase survival or reproduction in the prevailing environment. A) true B) false
A) true
Cancer is usually due to a series of mutations that occur in a single lineage of somatic cells. A) true B) false
A) true
p53 is an example of a(n): A) tumor suppressor. B) proto-oncogene. C) oncogene. D) cyclin-dependent kinase.
A) tumor suppressor.
Which answer choices does the effect of an insertion or deletion of a small number of nucleotides depend on? Select all that apply. A) whether it occurs in a coding region or noncoding region of the DNA B) whether it is a multiple of two C) whether it occurs in a germ-line cell or somatic cell D) whether it involves purine or pyrimidine bases
A) whether it occurs in a coding region or noncoding region of the DNA C) whether it occurs in a germ-line cell or somatic cell
A chemical agent that interferes with DNA repair may be considered a mutagen. A. True B. False
A. True
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 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.
B) The point mutation can be reversed by another point mutation but the deletion cannot.
The nonmutant allele of the BRCA1 gene helps to suppress tumor formation in women who are heterozygous for the mutation. Women heterozygous for BRCA1 nevertheless have a 50% to 70% chance of developing breast cancer before age 70 and the usual reason is that the nonmutant allele is lost or inactivated in a lineage of cells. One possible mechanism for such "loss of heterozygosity" is:
B) a somatic mutation in a breast cell inactivates the nonmutant BRCA1 allele.
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.
B) cause frameshift mutations.
A loss-of-function mutation is one in which the function of a gene is completely knocked out or obliterated. Frameshift mutations never result in the loss-of-function of a gene. A) true B) false
B) false
Genetic risk factors act independently of environment and lifestyle choices. A) true B) false
B) false
It is impossible to override a genetic predisposition to a disease such as skin cancer. A) true B) false
B) false
Somatic mutations are important to the evolutionary process; most cancers result from somatic mutations. A) true B) false
B) false
Which answer choices are the same in identical twins? Select all that apply. A) phenotype B) genotype C) karyotype D) DNA fingerprints E) fingerprints
B) genotype C) karyotype D) DNA fingerprints
In what situation can a harmful deletion in a chromosome persist in a population? A) if it is homozygous B) if the homologous chromosome lacks the deletion C) if the deletion is in the centromere D) if a transposon replaces the deleted region
B) if the homologous chromosome lacks the deletion
When a chromosome has either a duplication or a deletion, the chances that the mutation will be harmful are a function of: A) its size—the smaller the duplication or deletion, the greater the chance of harm. B) its size—the larger the duplication or deletion, the greater the chance of harm. C) its position on the chromosome—if it occurs at the tip of a long arm, it is likely to be less harmful than if it occurs at the tip of a short arm. D) None of the other answer options is correct.
B) its size—the larger the duplication or deletion, the greater the chance of harm.
In large genomes, most reciprocal translocations occur in: A) coding DNA. B) noncoding DNA. C) open reading frames. D) closed reading frames. E) inversion regions.
B) noncoding DNA.
In organisms with large genomes, inversions are more likely to be tolerated if the breakpoints occur in: A) coding DNA. B) noncoding DNA.
B) noncoding DNA.
Point mutations can impair a protein if they result in which of the answer choices? Select all that apply. A) synonymous codon B) nonsense codon C) nonsynonymous codon D) shift in reading frame
B) nonsense codon C) nonsynonymous codon D) shift in reading frame
Some genes have important functions in cells but they can sometimes acquire mutations that cause negative effects including the development of cancer. These genes are called: A) oncogenes. B) proto-oncogenes. C) tumor suppressor genes. D) viral genes.
B) proto-oncogenes.
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.
B) some individuals in the original population had the mutations that led to resistance.
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.
B) some somatic mutations in plants can affect future generations.
The human genome contains a family of genes that code for different forms of myosin. How different do you think the sequences of these genes are from each other? A) completely different no identical base sequences B) completely the same identical base sequence C) some differences in sequence some similarities
C) some differences in sequence some similarities
Reciprocal translocations can affect gene dosage in offspring because: A) the genes involved in the translocation are nonfunctional. B) the two chromosomes involved in the translocation may not assort together during meiosis. C) the two chromosomes involved in the translocation always assort together during meiosis. D) reciprocal translocation involves the duplication of one set of genes and the deletion of another set of genes. E) None of the other answer options is correct.
B) the two chromosomes involved in the translocation may not assort together during meiosis.
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 only to single-nucleotide frameshift mutations. B) The statement applies only to nucleotide changes that result in nonsense codons. C) "Random" means without regard for the needs of the organism
C) "Random" means without regard for the needs of the organism.
In the standard genetic code shown in Table 4.1, what fraction of codons are nonsense codons? A) 1/64 B) 2/64 C) 3/64 D) 4/64 E) 5/64
C) 3/64
Which of the statements applies to frameshift mutations? A) Frameshift mutations cause the insertion or deletion of a single amino acid from the polypeptide chain. B) Frameshift mutations create a premature stop codon at the site of the mutation. C) Frameshift mutations change the amino acid sequence downstream from the site of the mutation. D) Frameshift mutations are known risk factors in most forms of cancer, including breast and colon cancer. E) Frameshift mutations are known risk factors in breast cancer, but not colon cancer.
C) Frameshift mutations change the amino acid sequence downstream from the site of the mutation.
Cancer can be caused by mutations. Genetic analysis of a tumor found in a patient shows that the cell proliferation was triggered by a somatic mutation in the MYC gene causing this gene to be inappropriately activated. The patient is concerned about passing this cancer on to the children she plans to have in the future. Should she be concerned?
C) No, she should not worry about her children because this did not occur in a germ-line cell.
Which of the statements is true when a cell has a mutation in the p53 gene such that the p53 protein is not able to be phosphorylated? A) The amount of p53 protein in the nucleus would increase in response to DNA damage. B) The cell would arrest giving time for the DNA damage to be repaired. C) The cell would proceed through the cell cycle even in the presence of DNA damage. D) Nothing would change in the cell cycle because the p53 protein is normally not able to be phosphorylated.
C) The cell would proceed through the cell cycle even in the presence of DNA damage.
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.
C) a germ-line mutation in one of the genes implicated in the cancer occurred in an ancestor.
Which of the answer choices is most likely to result in a nonfunctional polypeptide? A) a silent mutation B) a missense mutation C) a nonsense mutation
C) a nonsense mutation
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 a germ-line cell B) a somatic mutation very early in development C) a somatic mutation late in development D) a germ-line mutation
C) a somatic mutation late in development
If a cytosine base in DNA is converted into uracil, the site is repaired by: A) DNA ligase. B) mismatch repair. C) base excision repair. D) nucleotide excision repair.
C) base excision repair.
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) All of these choices are correct.
C) delete amino acids in a polypeptide chain.
Which of the following is likely to be the type of mutation that is most harmful? A) reciprocal translocation B) gene inversion C) deletion of the centromere
C) deletion of the centromere
The human genome contains a family of genes that code for different forms of myosin which are expressed in different cell types and have somewhat different functions. Where in the sequence of each gene would you expect to see differences among them? A) regulatory region only B) protein-coding region only C) regulatory and protein-coding regions D) no difference in any part of the gene
C) regulatory and protein-coding regions
Which statements about mutations are false? Select all that apply. A) Mutations make evolution possible. B) Mutations result in genetic variation among individuals. C) Mutations accumulate in a genome over time. D) Mutations are usually caused by exposure to radiation. E) Mutations can be harmful, beneficial, or neutral. F) Mutations occur as a direct response to an organism's attempt to change one of its traits.
D) Mutations are usually caused by exposure to radiation. F) Mutations occur as a direct response to an organism's attempt to change one of its traits.
Which mutations in an animal somatic cell are inherited by the next generation? A) point mutations B) synonymous mutations C) deletions D) None of the other answer options is correct.
D) None of the other answer options is correct.
Any mutation that increases the risk of disease in an individual is known as a:
D) genetic risk factor.
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.
D) male germ-line cells undergo many more divisions than female germ-line cells.
The main mutagenic effects of ultraviolet light are chemical cross-links between adjacent thymines in a DNA strand. These could be repaired by: A) DNA replication. B) mismatch repair. C) base excision repair. D) nucleotide excision repair.
D) nucleotide excision repair.
Cancer-causing genes found in some viruses are called: A) coat protein genes. B) proto-oncogenes. C) tumor suppressor genes. D) oncogenes.
D) oncogenes.
Phosphorylated p53 is a protein that accumulates in the nuclei of cells that have damaged DNA where it functions to block the cell cycle and activate DNA repair. The p53 gene that encodes this protein is an example of a(n): A) protein kinase. B) proto-oncogene. C) oncogene. D) tumor suppressor gene.
D) tumor suppressor gene.
Mismatch repair, base excision repair, and nucleotide excision repair are similar in that each: A) repairs a single mismatched base. B) repairs a short strand of mismatched nucleotides. C) repairs multiple mismatched or damaged bases across a region. D) uses an undamaged segment of DNA as the template to repair a damaged segment of DNA. E) None of the other answer options is correct.
D) uses an undamaged segment of DNA as the template to repair a damaged segment of DNA.
see q 66.
b c d e
Which of the statements explains the fact that humans have a relatively large number of mutations per genome per generation when compared to other organisms? a. Most of these mutations happen after reproduction so they would not be selected against. b. Most of a human's DNA is noncoding so most of the mutations are neutral. c. Human cells do not divide as often as those of other organisms. d. Most of these mutations happen before reproduction and will not be transmitted to the progeny.
b. Most of a human's DNA is noncoding so most of the mutations are neutral.
Genetic studies have identified an allele (Δ32) that seems to provide protection against HIV. Which of the answer choices would explain the reason why our population has this mutation? a. This mutation was likely induced in the genome by the presence of HIV virus. b. This mutation likely benefited the human population against some other related pathogen. c. Our bodies are designed to protect us against a myriad of pathogens and the immune system was preparing for future viruses like HIV.
b. This mutation likely benefited the human population against some other related pathogen.
Which of the mutations would most likely have the least severe consequences? a. addition of one nucleotide b. addition of three nucleotides c. addition of two nucleotides d. deletion of one nucleotide
b. addition of three nucleotides
Mutations that affect only the individual in which they occur are called _____ mutations; _____ mutations are passed from parent to offspring. a. point; germ-line b. somatic; germ-line c. somatic; point d. germ-line; somatic e. germ-line; heritable
b. somatic; germ-line