1- GCD 3022 Quizzes 3 Questions With Complete Solutions
(Comprehension Q) During attenuation, when tryptophan levels
are high, the ( ) stem-loop forms and transcription ( ) the trpL
gene. Assume that translation is coupled with transcription.
Correct Answers 3-4, ends just past
(Comprehension Q) Expression levels of the lac operon in wild-
type cells are < 1% in the absence of lactose and 100% in the
presence of lactose, respectively. Which of the following
correctly estimates the expression level of the lac operon in a
lacI-mutant strain in the absence of lactose? Correct Answers
100%
(Comprehension Q) Expression levels of the lac operon in wild-
type cells are < 1% in the absence of lactose and 100% in the
presence of lactose, respectively. Which of the following
correctly estimates the expression level of the lac operon in a
lacO-mutant strain in the absence of lactose? Correct Answers
100%
(Comprehension Q) The combination of a 3-4 loop and a U-rich
attenuator sequence in the trp operon (see Fig. 14.12) is an
example of a rho-independent terminator (intrinsic terminator).
Would you expect attenuation to occur if the tryptophan levels
were high and mutations changed the attenuator sequence from
UUUUUUUU to UGGUUGUC? Correct Answers No,
attenuation would not occur, because the presence of G/C in this
sequence increases hydrogen bonds so that the dissociation of
mRNA from its template DNA is less likely to occur to
terminate transcription.
, (Comprehension Q) Which of the following events is NOT
involved in transcription of eukaryotic genes?
Histone deacetylation ahead of RNA polymerase
Re-formation of nucleosomes behind RNA polymerase
Histone eviction ahead of RNA polymerase
Histone acetylation ahead of RNA polymerase Correct Answers
Histone deacetylation ahead of RNA polymerase
A chromatin-remodeling complex may
1)change the loaction of nucleosomes
2)replace standard histones with histone variants
3)evict histones from DNA
4)Answer do all of these. Correct Answers 4)Answer do all of
these.
A repressor is a ( ) that (. ) transcription. Correct Answers
regulatory protein, inhibits
An activator is a ( ) that ( ) transcription. Correct Answers
regulatory protein, enhances
Another way for methylation at a CpG island to affect
transcription is that Correct Answers it may prevent the
binding of an activator to an enhancer, thereby decreasing
transcription.
Binding of ( ) to ( ) decreases the rate of transcription. Correct
Answers a repressor, a silencer
(Comprehension Q) During attenuation, when tryptophan levels
are high, the ( ) stem-loop forms and transcription ( ) the trpL
gene. Assume that translation is coupled with transcription.
Correct Answers 3-4, ends just past
(Comprehension Q) Expression levels of the lac operon in wild-
type cells are < 1% in the absence of lactose and 100% in the
presence of lactose, respectively. Which of the following
correctly estimates the expression level of the lac operon in a
lacI-mutant strain in the absence of lactose? Correct Answers
100%
(Comprehension Q) Expression levels of the lac operon in wild-
type cells are < 1% in the absence of lactose and 100% in the
presence of lactose, respectively. Which of the following
correctly estimates the expression level of the lac operon in a
lacO-mutant strain in the absence of lactose? Correct Answers
100%
(Comprehension Q) The combination of a 3-4 loop and a U-rich
attenuator sequence in the trp operon (see Fig. 14.12) is an
example of a rho-independent terminator (intrinsic terminator).
Would you expect attenuation to occur if the tryptophan levels
were high and mutations changed the attenuator sequence from
UUUUUUUU to UGGUUGUC? Correct Answers No,
attenuation would not occur, because the presence of G/C in this
sequence increases hydrogen bonds so that the dissociation of
mRNA from its template DNA is less likely to occur to
terminate transcription.
, (Comprehension Q) Which of the following events is NOT
involved in transcription of eukaryotic genes?
Histone deacetylation ahead of RNA polymerase
Re-formation of nucleosomes behind RNA polymerase
Histone eviction ahead of RNA polymerase
Histone acetylation ahead of RNA polymerase Correct Answers
Histone deacetylation ahead of RNA polymerase
A chromatin-remodeling complex may
1)change the loaction of nucleosomes
2)replace standard histones with histone variants
3)evict histones from DNA
4)Answer do all of these. Correct Answers 4)Answer do all of
these.
A repressor is a ( ) that (. ) transcription. Correct Answers
regulatory protein, inhibits
An activator is a ( ) that ( ) transcription. Correct Answers
regulatory protein, enhances
Another way for methylation at a CpG island to affect
transcription is that Correct Answers it may prevent the
binding of an activator to an enhancer, thereby decreasing
transcription.
Binding of ( ) to ( ) decreases the rate of transcription. Correct
Answers a repressor, a silencer
