Chapter 14 combined Learning Curve

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

generally increases with larger genomes.

A mutation that occurs in eggs and sperm or in the cells that give rise to these reproductive cells and therefore is passed on to the next generation.

germ-line mutation

Sites in the genome that are more susceptible to mutations than others are called: noncoding DNA. hotspots. risk factors. mutation spots. genes.

hotspots

Which of the following statements is true of a chromosome inversion?

-An inversion usually results from breakages in non-coding DNA. -An inversion results in the "flipping" of certain chromosomal segments. -Inversions can alter the order of genes within a chromosome. -Inversions are not always fatal for an organism.

Genetic risk factors:

-can increase the likelihood of somatic mutations. -can increase the likelihood of germ-line mutations. -can work synergistically with environmental risk factors. -can be heritable.

Which of the following enzymes is responsible for initiating certain types of base excision repair? DNA polymerase DNA ligase AP endonuclease DNA uracil glycosylase None of the answer options is correct.

DNA uracil glycosylase

When comparing DNA sequences of similar genes for proteins in related species, you see that some of the sequences are longer in one species compared to the other. Which of the following would most likely represent the extra number of bases that you would see? 5 7 17 21 25

21

A chromosomal mutation where a segment breaks off, flips, and then reattaches itself is called a(n): reciprocal translocation. translocation. deletion. duplication. inversion.

A chromosomal mutation where a segment breaks off, flips, and then reattaches itself is called a(n): reciprocal translocation. translocation. deletion. duplication. inversion.

An enzyme that uses the energy in ATP to close a nick in a DNA strand, joining the 3′ hydroxyl of one end to the 5′ phosphate of the other end.

DNA ligase

Which of the following enzymes is responsible for initiating the proofreading repair mechanism? DNA ligase DNA polymerase AP endonuclease DNA uracil glycosylase None of the answer options is correct.

DNA polymerase

_____ is the process where new genes evolve from duplicates of old ones. Deletion Centromere dosage Reciprocal translocation Duplication and divergence Inversion

Duplication and divergence

A trinucleotide of 5'CTC3' or 5'TTC3' is transcribed and then translated into the amino acid glutamic acid. A trinucleotide of 5'CAA3' or 5'TAC3' is transcribed and then translated into valine. In sickle-cell hemoglobin, valine is present instead of glutamic acid. Assuming a single base pair substitution has occurred, what is the mRNA code for valine in the affected mutant?

GUA

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.

a

Which of the following statements is true concerning the work of the Esther and Joshua Lederberg? a. Their work relied on a technique of bacterial culture known as "replica plating," and demonstrated that mutations occur randomly in organisms. b. Their work relied on a technique of bacterial culture known as "replica plating." c. Their work demonstrated that mutations cannot occur randomly in organisms. d. Their work demonstrated that mutations are determined by an organism's "needs." e. Their work demonstrated that mutations in organisms arise in response to environmental conditions.

a

Which of the following would you expect to have the lowest rate of point mutations per replication? DNA viruses humans RNA viruses fruit flies bacteria

Which of the following would you expect to have the lowest rate of point mutations per replication? DNA viruses humans RNA viruses fruit flies bacteria

Chromosomal aberrations: a. can be caused by errors during cell division. b. are typically only seen in the elderly. c. are usually fixed by DNA polymerase. d. can be caused by methylation.

a

Normally in corn, genes for waxy and virescent kernel appearance are linked. In a certain stock, however, it was found that these two genes assort independently. Which chromosomal aberration would explain this? a. translocation b. inversion c. duplication d. deletion e. None of the other answer options is correct.

a

A chromosomal segment that breaks off and attaches to another chromosome is what type of mutation? translocation inversion reciprocal translocation deletion duplication

all of these choices are correct

Mutation rates (per nucleotide per replication): are highest in viruses. are highest in bacteria. are similar across all organisms. are lower in organisms with larger genomes. are higher in organisms with larger genomes.

are highest in viruses

Replica plating showed that mutations for antibiotic resistance are not induced by the presence of the antibiotic because: a. antibiotic-resistant cells are able to form colonies in the absence of the antibiotic. b. antibiotic-resistant cells occur in colonies that never experienced the antibiotic. c. antibiotic-sensitive cells are unable to form colonies in the presence of the antibiotic. d. antibiotic-resistant cells are able to form colonies in the presence of the antibiotic.

b

Which of the following is the likely explanation for a flower showing multiple sectors with different coloration? a. the result of the plant being tetraploid b. the result of transposable elements c. the result of a germline mutation d. the result of the plant being triploid e. the result of a deletion

b

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? a. 3′-CTC-5′/5′-GAG-3′ to 5′-CAC-3′/3′-GTG-5′ b. 3′-CTC-5′/5′-GAG-3′ to 3′-CAC-5′/5′-GTG-3′ c. 5′-CTC-3′/3′-GAG-5′ to 5′-CAC-3′/3′-GTG-5′ d. 5′-CTC-3′/3′-GAG-5′ to 3′-CAC-5′/5′-GTG-3′

b. 3′-CTC-5′/5′-GAG-3′ to 3′-CAC-5′/5′-GTG-3′

A specialized repair system in which an incorrect DNA base and its sugar are both removed and the resulting gap is repaired base excision repair

base excision repair

What is one reason that RNA viruses and retroviruses have such a high rate of mutation?

because RNA is more fragile than DNA and because viral polymerases lack a proofreading mechanism.

In the procedure of replica plating, the purpose of the sterilized velvet is: a. to protect the agar plates from bacteria in the air. b. to protect the researchers from coming into contact with the bacteria. c. to transfer bacterial cells from one agar plate to another. d. to induce new mutations that can grow on the selective plates.

c

The fact that humans have a relatively large number of mutations per genome per generation when compared to other organisms can be explained by which of the following statements? a. Humans are so complex we have multiple proteins doing the same job. b. Most of these mutations happen after reproduction, so they wouldn't be selected against. c. Most of a human's DNA is noncoding, so most of the mutations are neutral. d. Humans have multiple proteins doing the same job, and our cells don't divide as often as other those of other organisms. e. Human cells don't divide as often as those of other organisms.

c

The rates of evolutionary change in DNA: a. are zero. b. can only be determined in conserved genes. c. are highly variable among different gene families. d. are constant in gene families with a diversity of members. e. are constant among different gene families and thus are used to estimate the time of divergence.

c

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 answer options is correct.

c

Genetic risk factors

can increase the likelihood of diseases. include mutations in the BRCA1 and BRCA2 genes. can work synergistically with environmental risk factors. can be heritable.

Mutations:

can leave the protein sequence intact.

A nonsense mutation: a. shifts the reading frame of a messenger RNA. b. changes the identity of one amino acid in a polypeptide chain. 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.

d

Imagine that a researcher is studying a mouse that carries a mutation in Pax7 —a gene that is involved in muscle development. To his surprise, these Pax7 mutant mice appear relatively normal. What is a possible explanation for this? a. Other members of the Pax gene family have redundant functions in muscle development (and can compensate for the Pax7 mutation). b. The normal copy of Pax7 on the corresponding homologous chromosome is sufficient for mouse survival. c. These Pax7 mutant mice may have a synonymous mutation. d. All of these choices are correct.

d

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. the needs of the organism. d. All of these choices are correct.

d

What is the difference between mismatch repair and nucleotide excision repair? a. In mismatch repair, several nucleotides are replaced, whereas in nucleotide excision repair the sugar phosphate backbone is fixed. b. In mismatch repair, several nucleotides are replaced, whereas in nucleotide excision repair it is just one. c. In mismatch repair, the sugar phosphate backbone is fixed, whereas in nucleotide excision repair, several nucleotides are replaced. d. In mismatch repair, one nucleotide is replaced, whereas in nucleotide excision repair several nucleotides are replaced.

d

Why do RNA viruses and retroviruses have such a high rate 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 therefore more likely to be damaged d. because viral polymerases lack a proofreading mechanism e. The third and fourth answers are true.

d

You are working in a lab studying a gene and notice that there are many other genes in the same organism that code for similar proteins. This is most likely the result of: deletion. transposition. duplication and divergence. reciprocal translocation. inversion.

duplication and divergence

A chemical compound would increase the mutation rate if it inhibited: Please choose the correct answer from the following choices, and then select the submit answer button. a. mismatch repair. b. nucleotide excision repair. c. base excision repair. d. DNA ligase. e. All of these choices are correct.

e

DNA repair: a. is only active during DNA replication. b. involves a set of proteins that are always active. c. always prevents errors. d. can fix chromosomal inversions and translocations. e. can involve excision of bases flanking a distortion in the helix.

e

Which of the following statements is true regarding a chromosome deletion? a. Chromosome deletions do not affect gene dosage. b. If a deletion eliminates the centromere, the chromosome is still passed on during cell division. c. Small chromosomal deletions usually have serious and often fatal consequences for an organism. d. Small chromosomal deletions are easily detected by microscopy. e. None of the answer options is correct.

e

eA transposable element can insert into any position in the genome except: a. regions near the telomere. b. regions near the centromere. c. regions near sequences coding for ribosomal RNA. d. inside another transposon. e. All of these choices are correct.

e

A researcher has carried out Giesma staining on a set of human chromosomes, and has arranged these chromosomes into a karyotype. He notices that in a homologous pair, a band is missing from one of the chromosomes. This likely resulted from: a deletion. a duplication. an inversion. a reciprocal translocation. either a deletion or a reciprocal translocation.

either a deletion or a reciprocal translocation.

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

false

Any deviation in normal gene dosage is lethal.

false

Consider a polyploid plant that has several copies of each of its genes. This plant will likely die prematurely, given this high gene dosage.

false

DNA ligase is responsible for repairing thymine dimers caused by UV light. true false

false

In base excision repair, a whole segment of DNA is removed and resynthesized. true false

false

Mutations will always decrease the activity of a gene.

false

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

false

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

false

falseA silent mutation is a mutation that only occurs in noncoding regions of DNA. true false

false

Which of the following mutations would most likely have the most severe consequence? silent addition of a codon frameshift missense

frameshift

Which of the following mechanisms would most likely be involved in repairing a single point mutation?

mismatch repair and/or base excision repair

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

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? nonsense base pair deletion frameshift missense silent

missense

Sickle-cell anemia results from what type of mutation? silent missense frameshift base pair deletion nonsense

missense

The GAG codon, which codes for glutamic acid, is mutated to GUG, which now codes for valine. What type of mutation is this?

missense

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

A point mutation that changes a UAC codon into a UAG codon is: frameshift mutation. silent mutation. missense mutation. nonsense mutation.

nonsense mutation.

A mutation in which a base pair is replaced by a different base pair; this is the most frequent type of mutation; also known as a nucleotide substitution.

point mutation

The correction of a mismatched base in a DNA strand by cleaving one of the strand backbones, degrading the sequence with the mismatch, and resynthesizing from the intact DNA strand. postreplication mismatch repair

postreplication mismatch repair

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 transposition duplication deletion inversion

reciprocal translocation

A transposable element can insert into any position in the genome except

regions near the telomere. regions near the centromere. regions near sequences coding for ribosomal RNA. inside another transposon. (all of the above)

A mutation resulting in a codon that does not alter the corresponding amino acid in the polypeptide. synonymous (silent) mutation

synonymous (silent) mutation

Which of the following would best describe the results seen in a flower whose sectors have different pigmentation?

the result of transposable elements

A chromosomal segment that breaks off and attaches to another chromosome is what type of mutation? translocation inversion reciprocal translocation deletion duplication

translocation

A chromosomal segment that breaks off and inserts into another chromosome is what type of mutation?

translocation

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 inversion duplication deletion None of the other answer options is correct.

translocation

A chromosomal mutation in which a segment (not containing a centromere) is missing is called a deletion.

true

A nucleotide substitution typically has less severe consequences than a nucleotide addition or deletion. true false

true

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

true

Dosage refers to the number of copies of each gene in a cell. true false

true

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

true

Generally speaking, a nucleotide substitution has less severe consequences than a nucleotide addition/deletion.

true

Insertion of one nucleotide in a gene will lead to a frameshift mutation. true false

true

Movable DNA sequences that can "jump" from one spot in the genome to another are called transposable elements.

true

Mutagens increase the amount of damage to DNA. true false

true

Only germ line mutations are transmitted to the progeny.

true

Only germline mutations are transmitted to the progeny. true false

true