Biology 2107 Chapter 14

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

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. All of the answer options are correct.

All of the answer options are correct.

What is one reason that RNA viruses and retroviruses have such a high rate of mutation? Because RNA replication is much more prone to mistakes Because RNA viruses and retroviruses initially cause mutations during replication Because RNA is more fragile than DNA and therefore more likely to be damaged Because they lack a proofreading mechanism Because RNA is more fragile than DNA and because viral polymerases lack a proofreading mechanism.

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

Any deviation in normal gene dosage is lethal. true false

F

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? GAG GUA CUU UUG GAA

GUA

Which of the following statements is true regarding a chromosome deletion? Chromosome deletions have no relationship to gene dosage. If a deletion affects a centromere, this mutated chromosome will be easily passed on during cell division. Chromosomal deletions also have serious―typically fatal―ramifications for an organism. Chromosome deletions are always fatal due to the presence of homologous chromosomes. None of the answer options are true.

None of the answer options are true.

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

T

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

T

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

T

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

T

Only germ line mutations are transmitted to the progeny. true false

T

Which of the following statements concerning cancer and mutations is correct? Cancer can only occur with a mutation in a somatic cell. Cancer can only occur with a mutation in a germ cell. Usually multiple mutations are required in different genes to cause cancer. Usually a single mutation is all that is required to cause cancer. None of the answer options is correct.

Usually multiple mutations are required in different genes to cause cancer.

A researcher has carried out Giesma staining on a set of human chromosomes, and has arranged these chromosomes into a karyotype. She 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.

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

frameshift

The amount of new mutations in living organisms following a round of genome replication: generally increases with larger genomes. generally decreases with larger genomes. is similar independent of genome size. is highest in the bacteria. None of the answer options is correct.

generally increases with larger genomes.

Sickle-cell anemia is an example of what type of mutation? frameshift nonsense silent missense base pair deletion

missense

The GAG codon, which codes for glutamic acid, is mutated to GUG, which now codes for valine. What type of mutation is this? base pair deletion nonsense silent missense frameshift

missense

A point mutation that now codes for the wrong amino acid is called a: missense mutation. nonsense mutation. frameshift mutation. silent mutation.

missense mutation.

Which of the following would best describe the results seen in a flower whose sectors have different pigmentation? the result of the plant being tetraploid the result of a germ-line mutation the result of the plant being triploid the result of transposable elements the result of a deletion

the result of transposable elements

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? Other members of the Pax gene family have redundant functions in muscle development (and can compensate for the Pax7 mutation). The normal copy of Pax7 on the corresponding homologous chromosome is sufficient for mouse survival. These Pax7 mutant mice may have a synonymous mutation. All answer options are correct.

All answer options are correct.

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

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

F

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

F

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

F

DNA polymerase is responsible for the process called mismatch repair. true false

F

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

F

Mutations will always decrease the activity of a gene. true false

F

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

F

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

F

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

In mismatch repair, one nucleotide is replaced, whereas in nucleotide excision repair several nucleotides are replaced.

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

Their work relied on a technique of bacterial culture known as "replica-plating," and demonstrated that mutations occur randomly within organisms.

Mutation rates (of nucleotides): are highest in viruses. are lower in organisms with larger genomes. are similar across all organisms. are higher in organisms with larger genomes. are highest in the bacteria.

are highest in viruses.

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

are highly variable among different gene families.

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

can involve excision of bases flanking a distortion in the helix.

Mutations: can leave the protein sequence intact. will result in a different phenotype. will be corrected. will be passed onto offspring. None of the answer options is correct.

can leave the protein sequence intact.

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

hotspots.

A point mutation that causes a premature stop codon is called a: frameshift mutation. nonsense mutation. missense mutation. silent mutation.

nonsense mutation.

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

translocation