GENETICS EXAM 4 KEY CONCEPTS AND
PRACTICE QUESTIONS
◉ Let's suppose a gene in mice is found in two different alleles,
which we call allele D and d. The gene is 454 bp in length, and the D
and d alleles differ from each other at 8 different sites within this
gene. If gene conversion changed the d allele into the D allele, which
mechanism would you favor to explain the conversion.
Answer: Nucleotide excision repair
◉ A gene exists in two alleles, which we will call B and b. The gene is
1123 bp in length, and the B and b alleles exhibit single base pair
differences at six different sites. If gene conversion changed the b
allele into the B allele, which mechanism would you favor to explain
the conversion.
Answer: Gap repair synthesis
◉ A mutation changes a codon to another codon that changes the
original amino acid to a different amino acid. This is a.
Answer: missense mutation
◉ A mutation changes a codon to another codon that does not
change the original amino acid to a different amino acid. This is a.
Answer: silent mutation.
,◉ Which of the following is a cause of spontaneous mutations?.
Answer: A tautomeric shift that causes mis-base pairing
◉ Which of the following is not a mutagen that can cause induced
mutations?.
Answer: A tautomeric shift that causes mis-base pairing
◉ During nucleotide excision repair, the role of UvrC is to.
Answer: make cuts on either side of the lesion.
◉ A mutagen that alkylates bases is:.
Answer: ethyl methanesulfonate (EMS)
◉ What is the mechanism by which X-rays induce mutations?.
Answer: Inducing DNA double-stranded breaks
◉ In the Ames test, a ( ) number of colonies is observed if a
substrate ( ) a mutagen, compared with the control that is not
exposed to the suspected mutagen..
Answer: significantly higher, is
, ◉ Patients with Xeroderma pigmentosum are highly susceptible to (
), as they have a defect in ( )..
Answer: skin cancer, nucleotide excision repair
◉ An advantage of translesion DNA polymerases is they can
replicate ( ), but a disadvantage is they ( )..
Answer: over damaged DNA, have low fidelity
◉ During homologous recombination, how is a heteroduplex
formed?.
Answer: By the migration of a Holliday junction
◉ Which of the following proteins is/are used by a transposon,
which is a transposable element that moves via a segment of DNA?.
Answer: Transposase
◉ Which of the following statements regarding retrotransposons is
the most accurate?.
Answer: Retrotransposons are most abundant in the genomes of
complex, multicellular eukaryotes.
◉ Which of the following statements regarding retrotransposons
(also called retroelements) is false?.
PRACTICE QUESTIONS
◉ Let's suppose a gene in mice is found in two different alleles,
which we call allele D and d. The gene is 454 bp in length, and the D
and d alleles differ from each other at 8 different sites within this
gene. If gene conversion changed the d allele into the D allele, which
mechanism would you favor to explain the conversion.
Answer: Nucleotide excision repair
◉ A gene exists in two alleles, which we will call B and b. The gene is
1123 bp in length, and the B and b alleles exhibit single base pair
differences at six different sites. If gene conversion changed the b
allele into the B allele, which mechanism would you favor to explain
the conversion.
Answer: Gap repair synthesis
◉ A mutation changes a codon to another codon that changes the
original amino acid to a different amino acid. This is a.
Answer: missense mutation
◉ A mutation changes a codon to another codon that does not
change the original amino acid to a different amino acid. This is a.
Answer: silent mutation.
,◉ Which of the following is a cause of spontaneous mutations?.
Answer: A tautomeric shift that causes mis-base pairing
◉ Which of the following is not a mutagen that can cause induced
mutations?.
Answer: A tautomeric shift that causes mis-base pairing
◉ During nucleotide excision repair, the role of UvrC is to.
Answer: make cuts on either side of the lesion.
◉ A mutagen that alkylates bases is:.
Answer: ethyl methanesulfonate (EMS)
◉ What is the mechanism by which X-rays induce mutations?.
Answer: Inducing DNA double-stranded breaks
◉ In the Ames test, a ( ) number of colonies is observed if a
substrate ( ) a mutagen, compared with the control that is not
exposed to the suspected mutagen..
Answer: significantly higher, is
, ◉ Patients with Xeroderma pigmentosum are highly susceptible to (
), as they have a defect in ( )..
Answer: skin cancer, nucleotide excision repair
◉ An advantage of translesion DNA polymerases is they can
replicate ( ), but a disadvantage is they ( )..
Answer: over damaged DNA, have low fidelity
◉ During homologous recombination, how is a heteroduplex
formed?.
Answer: By the migration of a Holliday junction
◉ Which of the following proteins is/are used by a transposon,
which is a transposable element that moves via a segment of DNA?.
Answer: Transposase
◉ Which of the following statements regarding retrotransposons is
the most accurate?.
Answer: Retrotransposons are most abundant in the genomes of
complex, multicellular eukaryotes.
◉ Which of the following statements regarding retrotransposons
(also called retroelements) is false?.
