GCD 3022 Exam IV Questions With Complete Solutions
An advantage of translesion-replicating polymerases is that they
can replicate ( ), but a disadvantage is that they ( ).
over damaged DNA, have low fidelity
(Comprehension Q) Marfan syndrome is a genetic disease of the
connective tissue. It is caused by an autosomal dominant
mutation within a gene called FBN1. Among 1,000,000 live
births, 200 babies developed this disease. Among those 200
babies, 180 of them had one parent with Marfan syndrome.
Calculate mutation rate and mutation frequency at this gene.
Mutation rate: 1 x 10^-5, Mutation frequency: 1 x 10^-4
Mutation rate: A likelihood for a new mutation to occur
Among 200 babies, 180 babies inherited a preexisting FBN1
mutant allele from one of their parents. This means that 20
babies had a new mutant FBN1 allele.
20 mutant alleles/1, 000,000 babies x 2 alleles (we are diploid!)
= 1 x 10^-5
Mutation Frequency: The number of mutant alleles (genes)/all
alleles (genes)
200 mutant alleles/1, 000, 000 babies x 2 alleles (we are
diploid!) = 1 x 10-4
(Comprehension Q) For an Ames test, two different His- strains
are available; one detects base substitutions (His-A) and the
, other frameshift mutations (His-B). After culturing these strains
with ethyl methanesulfonate (EMS) separately, we plated cells
on media lacking histidine. Which of the following correctly
predicts the results from this experiment?
Compared to untreated control groups, the number of revertant
colonies should be increased for His-A strain (base
substitutions) but not for His-B strain (frameshift mutations).
(Comprehension Q) Depurination creates an apurinic (AP) site.
If not repaired, it can cause a base substitution during DNA
replication (see Fig. 19.7). Which of the following may repair
AP sites prior to DNA replication?
Base excision repair
(Comprehension Q) In E. coli, a methyltransferase enzyme
encoded by the dam gene recognizes the sequence of 5'-GATC-
3' and attaches a methyl group to the nitrogen at position 6 of
adenine. E. coli strains that are missing the dam gene are known
to have higher rates of spontaneous mutations than wild-type
strains. Why?
This is because these strains are unable to recognize the parental
strand as a repair template to remove incorrect bases in the
daughter strand during mismatch repair.
A mutation activates a Ras proto-oncogene to become an
oncogene. Which of the following best describes the nature of
this mutation?
Gain of function
An advantage of translesion-replicating polymerases is that they
can replicate ( ), but a disadvantage is that they ( ).
over damaged DNA, have low fidelity
(Comprehension Q) Marfan syndrome is a genetic disease of the
connective tissue. It is caused by an autosomal dominant
mutation within a gene called FBN1. Among 1,000,000 live
births, 200 babies developed this disease. Among those 200
babies, 180 of them had one parent with Marfan syndrome.
Calculate mutation rate and mutation frequency at this gene.
Mutation rate: 1 x 10^-5, Mutation frequency: 1 x 10^-4
Mutation rate: A likelihood for a new mutation to occur
Among 200 babies, 180 babies inherited a preexisting FBN1
mutant allele from one of their parents. This means that 20
babies had a new mutant FBN1 allele.
20 mutant alleles/1, 000,000 babies x 2 alleles (we are diploid!)
= 1 x 10^-5
Mutation Frequency: The number of mutant alleles (genes)/all
alleles (genes)
200 mutant alleles/1, 000, 000 babies x 2 alleles (we are
diploid!) = 1 x 10-4
(Comprehension Q) For an Ames test, two different His- strains
are available; one detects base substitutions (His-A) and the
, other frameshift mutations (His-B). After culturing these strains
with ethyl methanesulfonate (EMS) separately, we plated cells
on media lacking histidine. Which of the following correctly
predicts the results from this experiment?
Compared to untreated control groups, the number of revertant
colonies should be increased for His-A strain (base
substitutions) but not for His-B strain (frameshift mutations).
(Comprehension Q) Depurination creates an apurinic (AP) site.
If not repaired, it can cause a base substitution during DNA
replication (see Fig. 19.7). Which of the following may repair
AP sites prior to DNA replication?
Base excision repair
(Comprehension Q) In E. coli, a methyltransferase enzyme
encoded by the dam gene recognizes the sequence of 5'-GATC-
3' and attaches a methyl group to the nitrogen at position 6 of
adenine. E. coli strains that are missing the dam gene are known
to have higher rates of spontaneous mutations than wild-type
strains. Why?
This is because these strains are unable to recognize the parental
strand as a repair template to remove incorrect bases in the
daughter strand during mismatch repair.
A mutation activates a Ras proto-oncogene to become an
oncogene. Which of the following best describes the nature of
this mutation?
Gain of function
