GCD 3022 Exam Three Questions With Complete Solutions
1. A drug, which we will call drug X, inhibits the protein kinase
that phosphorylates the CREB protein.
How would drug X affect the following events?
A. The ability of the CREB protein to bind to CREs
B. The ability of extracellular hormone to enhance cAMP levels
C. The ability of the CREB protein to stimulate transcription
D. The ability of the CREB protein to dimerize Correct
Answers A, B and D: no effect
C: would inhibit the CREB proteins ability to stimulate
transcription
A codon is 5'-CCA-3'. An anticodon that would recognize this
codon would be Correct Answers 3'-GGU-5'
A codon that specifies an amino acid near the amino terminus of
a polypeptide would be Correct Answers located closer to the
5' end of a mature mRNA.
A gene encodes a pre-mRNA with 5 exons and 4 introns. A
mutation eliminates the 3' splice site from intron 3. What exons
would be found in the mRNA after splicing was completed?
Correct Answers Exon 1, 2, 3, 5
A gene is under negative control. The presence of a small
effector molecule causes the gene to
be expressed at high levels. Which of the following mechanism
could explain the action of this small
effector molecule? Correct Answers it is an inducer that causes
a repressor to not bind to the DNA
, A mutation alters the sequence of the lac operator in a way that
prevents the lac repressor from binding to the lac operator. How
would you expect this mutation to affect the regulation of the lac
operon? Assume that no glucose is present. Correct Answers
The operon would be turned on in the presence or absence of
lactose in the environment.
A mutation in the lacZ gene alters β-galactosidase so it makes
more allolactose compared with a normal β-galactosidase
enzyme. How would this mutation affect the expression of the
lac operon? Correct Answers It would require less lactose in
the environment to express the lac operon
A mutation introduces a stop codon into the middle of a gene
that encodes a polypeptide. Which of the following is not true?
Correct Answers the mRNA would be shorter (no because
transcription would not be affected.)
A research study involving humans has shown that maternal
anxiety during pregnancy can
decrease the methylation of the ICR located between the
H19 gene and the Igf2 gene. How would
this decrease affect the expression of the maternal and paternal
alleles that the offspring carries?
Would you expect the decrease to affect growth? Correct
Answers The ICR of the maternal allele is not methylated, so
inhibiting DNA methylation would
not affect this allele, which is already silenced. If the
methylation of the paternal allele were
1. A drug, which we will call drug X, inhibits the protein kinase
that phosphorylates the CREB protein.
How would drug X affect the following events?
A. The ability of the CREB protein to bind to CREs
B. The ability of extracellular hormone to enhance cAMP levels
C. The ability of the CREB protein to stimulate transcription
D. The ability of the CREB protein to dimerize Correct
Answers A, B and D: no effect
C: would inhibit the CREB proteins ability to stimulate
transcription
A codon is 5'-CCA-3'. An anticodon that would recognize this
codon would be Correct Answers 3'-GGU-5'
A codon that specifies an amino acid near the amino terminus of
a polypeptide would be Correct Answers located closer to the
5' end of a mature mRNA.
A gene encodes a pre-mRNA with 5 exons and 4 introns. A
mutation eliminates the 3' splice site from intron 3. What exons
would be found in the mRNA after splicing was completed?
Correct Answers Exon 1, 2, 3, 5
A gene is under negative control. The presence of a small
effector molecule causes the gene to
be expressed at high levels. Which of the following mechanism
could explain the action of this small
effector molecule? Correct Answers it is an inducer that causes
a repressor to not bind to the DNA
, A mutation alters the sequence of the lac operator in a way that
prevents the lac repressor from binding to the lac operator. How
would you expect this mutation to affect the regulation of the lac
operon? Assume that no glucose is present. Correct Answers
The operon would be turned on in the presence or absence of
lactose in the environment.
A mutation in the lacZ gene alters β-galactosidase so it makes
more allolactose compared with a normal β-galactosidase
enzyme. How would this mutation affect the expression of the
lac operon? Correct Answers It would require less lactose in
the environment to express the lac operon
A mutation introduces a stop codon into the middle of a gene
that encodes a polypeptide. Which of the following is not true?
Correct Answers the mRNA would be shorter (no because
transcription would not be affected.)
A research study involving humans has shown that maternal
anxiety during pregnancy can
decrease the methylation of the ICR located between the
H19 gene and the Igf2 gene. How would
this decrease affect the expression of the maternal and paternal
alleles that the offspring carries?
Would you expect the decrease to affect growth? Correct
Answers The ICR of the maternal allele is not methylated, so
inhibiting DNA methylation would
not affect this allele, which is already silenced. If the
methylation of the paternal allele were
