ASU BIO 340 Exam 3 Questions and
Answers 100% Pass
What will be the effect on transcription when an inhibitor is in play?
A. Allow transcription B. Prevent transcription -
CORRECT ANSWER: B Explanation: An inhibitor prevents activator
from binding to DNA; activators are used in positive regulation
(increasing transcription) - thus, the inhibitor prevents the activator
from positive regulating (increasing) transcription.
QUESTION: What will be the effect on transcription when an inducer
is in play?
A. Allow transcription B. Prevent transcription -
CORRECT ANSWER: A Explanation: When an inducer is in play, it
will allow transcription.
,QUESTION: For a gene under positive control, which of the following
would prevent transcription?
A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor -
CORRECT ANSWER: E Explanation: Positive regulation includes
activators (affected by effectors and inhibitors); inhibitors prevent
activator from binding to DNA, thus preventing transcription.
QUESTION: For a gene under negative control, which of the following
would you expect to find bound to the repressor if there is active
transcription? A. Repressor B. Corepressor C. Inducer D. Effector E.
Inhibitor -
CORRECT ANSWER: C Explanation: In negative regulation, there are
repressors (affected by correpressors and inducers). If there were a
corepressor, the repressor would successfully bind to the operator and
prevent transcription. Inducers, however, prevent the binding of the
repressor - thus causing a prevention of it doing its job, and allowing
transcription.
, QUESTION: Which molecule serves as the inducer for the lac operon?
A. cAMP B. Glucose C. Lactose D. Allolactose -
CORRECT ANSWER: D Explanation: Allolactose is the molecule that
binds to repressor protein, making it unable to bind to the operator.
QUESTION: Which of the following conditions will result in the
greatest levels of transcription of the lac operon?
A. Lactose absent, glucose absent B. Lactose absent, glucose present C.
Lactose present, glucose present D. Lactose present, glucose absen -
CORRECT ANSWER: D Explanation: From the perspective of the
cell, it is most efficient to repress expression of the genes allowing for
metabolism of lactose when it's absent, to allow it when present, but
only to prioritize it when glucose (the preferred food source) is absent.
In C, allolactose will also be present, allowing transcription, but positive
regulation (i.e. increase in transcription) only happens as in D, when
glucose is absent.
Answers 100% Pass
What will be the effect on transcription when an inhibitor is in play?
A. Allow transcription B. Prevent transcription -
CORRECT ANSWER: B Explanation: An inhibitor prevents activator
from binding to DNA; activators are used in positive regulation
(increasing transcription) - thus, the inhibitor prevents the activator
from positive regulating (increasing) transcription.
QUESTION: What will be the effect on transcription when an inducer
is in play?
A. Allow transcription B. Prevent transcription -
CORRECT ANSWER: A Explanation: When an inducer is in play, it
will allow transcription.
,QUESTION: For a gene under positive control, which of the following
would prevent transcription?
A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor -
CORRECT ANSWER: E Explanation: Positive regulation includes
activators (affected by effectors and inhibitors); inhibitors prevent
activator from binding to DNA, thus preventing transcription.
QUESTION: For a gene under negative control, which of the following
would you expect to find bound to the repressor if there is active
transcription? A. Repressor B. Corepressor C. Inducer D. Effector E.
Inhibitor -
CORRECT ANSWER: C Explanation: In negative regulation, there are
repressors (affected by correpressors and inducers). If there were a
corepressor, the repressor would successfully bind to the operator and
prevent transcription. Inducers, however, prevent the binding of the
repressor - thus causing a prevention of it doing its job, and allowing
transcription.
, QUESTION: Which molecule serves as the inducer for the lac operon?
A. cAMP B. Glucose C. Lactose D. Allolactose -
CORRECT ANSWER: D Explanation: Allolactose is the molecule that
binds to repressor protein, making it unable to bind to the operator.
QUESTION: Which of the following conditions will result in the
greatest levels of transcription of the lac operon?
A. Lactose absent, glucose absent B. Lactose absent, glucose present C.
Lactose present, glucose present D. Lactose present, glucose absen -
CORRECT ANSWER: D Explanation: From the perspective of the
cell, it is most efficient to repress expression of the genes allowing for
metabolism of lactose when it's absent, to allow it when present, but
only to prioritize it when glucose (the preferred food source) is absent.
In C, allolactose will also be present, allowing transcription, but positive
regulation (i.e. increase in transcription) only happens as in D, when
glucose is absent.
