BIOLOGY 203 EXAM 4 QUESTIONS &
ANSWERS (RATED A+)
Which of the following is a protein produced by a regulatory gene?
A) operon
B) inducer
C) promoter
D) repressor - ANSWERD) repressor
A lack of which molecule would result in a cell's inability to "turn off" genes?
A) operon
B) inducer
C) promoter
D) corepressor - ANSWERD) corepressor
Which method is utilized by eukaryotes to control their gene expression that is NOT
used in bacteria?
A) control of chromatin remodeling
B) control of RNA splicing
C) transcriptional control
D) control of both RNA splicing and chromatin remodeling - ANSWERD) control of
both RNA splicing and chromatin remodeling
The phenomenon in which RNA molecules in a cell are destroyed if they have a
sequence complementary to an introduced double-stranded RNA is called _____.
A) RNA interference
B) RNA obstruction
C) RNA blocking
D) RNA disposal - ANSWERA) RNA interference
Which of the following is true of embryonic stem cells but not of adult stem cells?
A) One aim of using them is to provide cells for repair of diseased tissue
B) They can provide enormous amounts of information about the process of gene
regulation
C) They normally differentiate into only eggs and sperm
D) They can continue to reproduce for an indefinite period
E) They can give rise to all cell types in the organism - ANSWERE) They can give
rise to all cell types in the organism
DNA microarrays have made a huge impact on genomic studies because they
A) can be used to eliminate the function of any gene in the genome
B) allow the expression of many or even all of the genes in the genome to be
compared at once
C) allow physical maps of the genome to be assembled in a very short time
,D) dramatically enhance the efficiency of restriction enzymes
E) can be used to introduce entire genomes into bacterial cells - ANSWERB) allow
the expression of many or even all of the genes in the genome to be compared at
once
Which of the following, when taken up by a cell, binds to a repressor so that the
repressor no longer binds to the operator?
A) inducer
B) promoter
C) repressor
D) corepressor - ANSWERA) inducer
Most repressor proteins are allosteric. Which of the following binds with the
repressor to alter its conformation?
A) inducer
B) promoter
C) transcription factor
D) cAMP - ANSWERA) inducer
A mutation that inactivates a regulatory gene of a repressible operon in an E. coli cell
would result in _____.
A) continuous transcription of the structural gene controlled by that regulator
B) complete inhibition of transcription of the structural gene controlled by that
regulator
C) irreversible binding of the repressor to the operator
D) continuous translation of the mRNA because of alteration of its structure -
ANSWERA) continuous transcription of the structural gene controlled by that
regulator
The lactose operon is likely to be transcribed when _____.
A) there is more glucose in the cell than lactose
B) there is glucose but no lactose in the cell
C) the cyclic AMP and lactose levels are both high within the cell
D) the cAMP level is high and the lactose level is low - ANSWERC) the cyclic AMP
and lactose levels are both high within the cell
Transcription of structural genes in an inducible operon _____.
A) occurs continuously in the cell
B) starts when the pathway's substrate is present
C) starts when the pathway's product is present
D) stops when the pathway's product is present - ANSWERB) starts when the
pathway's substrate is present
For a repressible operon to be transcribed, which of the following must occur?
A) A corepressor must be present.
B) RNA polymerase and the active repressor must be present.
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
D) RNA polymerase must not occupy the promoter, and the repressor must be
inactive. - ANSWERC) RNA polymerase must bind to the promoter, and the
repressor must be inactive.
, Altering patterns of gene expression in prokaryotes would most likely serve an
organism's survival by _____.
A) organizing gene expression, so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing an organism to adjust to changes in environmental conditions
D) allowing environmental changes to alter a prokaryote's genome - ANSWERC)
allowing an organism to adjust to changes in environmental conditions
In positive control of several sugar-metabolism-related operons, the catabolite
activator protein (CAP) binds to DNA to stimulate transcription. What causes an
increase in CAP activity in stimulating transcription?
A) an increase in glucose and an increase in cAMP
B) a decrease in glucose and an increase in cAMP
C) an increase in glucose and a decrease in cAMP
D) a decrease in glucose and a decrease in the repressor - ANSWERB) a decrease
in glucose and an increase in cAMP
There is a mutation in the repressor that results in a molecule known as a super-
repressor because it represses the lac operon permanently. Which of these would
characterize such a mutant?
A) It cannot bind to the operator.
B) It cannot make a functional repressor.
C) It cannot bind to the inducer.
D) It makes a repressor that binds CAP. - ANSWERC) It cannot bind to the inducer.
If she moves the promoter for the lac operon to the region between the beta
galactosidase (lacZ) gene and the permease (lacY) gene, which of the following
would be likely?
A) The three structural genes will be expressed normally.
B) RNA polymerase will no longer transcribe permease.
C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be
translated.
D) Beta galactosidase will not be produced. - ANSWERD) Beta galactosidase will
not be produced.
If she moves the operator to the far end of the operon, past the transacetylase (lacA)
gene, which of the following would likely occur when the cell is exposed to lactose?
A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The structural genes will be transcribed continuously. - ANSWERD) The structural
genes will be transcribed continuously.
If she moves the repressor gene (lacI), along with its promoter, to a position at some
several thousand base pairs away from its normal position, we would expect the
_____.
A) repressor will no longer bind to the operator
B) repressor will no longer bind to the inducer
C) lac operon will be expressed continuously
ANSWERS (RATED A+)
Which of the following is a protein produced by a regulatory gene?
A) operon
B) inducer
C) promoter
D) repressor - ANSWERD) repressor
A lack of which molecule would result in a cell's inability to "turn off" genes?
A) operon
B) inducer
C) promoter
D) corepressor - ANSWERD) corepressor
Which method is utilized by eukaryotes to control their gene expression that is NOT
used in bacteria?
A) control of chromatin remodeling
B) control of RNA splicing
C) transcriptional control
D) control of both RNA splicing and chromatin remodeling - ANSWERD) control of
both RNA splicing and chromatin remodeling
The phenomenon in which RNA molecules in a cell are destroyed if they have a
sequence complementary to an introduced double-stranded RNA is called _____.
A) RNA interference
B) RNA obstruction
C) RNA blocking
D) RNA disposal - ANSWERA) RNA interference
Which of the following is true of embryonic stem cells but not of adult stem cells?
A) One aim of using them is to provide cells for repair of diseased tissue
B) They can provide enormous amounts of information about the process of gene
regulation
C) They normally differentiate into only eggs and sperm
D) They can continue to reproduce for an indefinite period
E) They can give rise to all cell types in the organism - ANSWERE) They can give
rise to all cell types in the organism
DNA microarrays have made a huge impact on genomic studies because they
A) can be used to eliminate the function of any gene in the genome
B) allow the expression of many or even all of the genes in the genome to be
compared at once
C) allow physical maps of the genome to be assembled in a very short time
,D) dramatically enhance the efficiency of restriction enzymes
E) can be used to introduce entire genomes into bacterial cells - ANSWERB) allow
the expression of many or even all of the genes in the genome to be compared at
once
Which of the following, when taken up by a cell, binds to a repressor so that the
repressor no longer binds to the operator?
A) inducer
B) promoter
C) repressor
D) corepressor - ANSWERA) inducer
Most repressor proteins are allosteric. Which of the following binds with the
repressor to alter its conformation?
A) inducer
B) promoter
C) transcription factor
D) cAMP - ANSWERA) inducer
A mutation that inactivates a regulatory gene of a repressible operon in an E. coli cell
would result in _____.
A) continuous transcription of the structural gene controlled by that regulator
B) complete inhibition of transcription of the structural gene controlled by that
regulator
C) irreversible binding of the repressor to the operator
D) continuous translation of the mRNA because of alteration of its structure -
ANSWERA) continuous transcription of the structural gene controlled by that
regulator
The lactose operon is likely to be transcribed when _____.
A) there is more glucose in the cell than lactose
B) there is glucose but no lactose in the cell
C) the cyclic AMP and lactose levels are both high within the cell
D) the cAMP level is high and the lactose level is low - ANSWERC) the cyclic AMP
and lactose levels are both high within the cell
Transcription of structural genes in an inducible operon _____.
A) occurs continuously in the cell
B) starts when the pathway's substrate is present
C) starts when the pathway's product is present
D) stops when the pathway's product is present - ANSWERB) starts when the
pathway's substrate is present
For a repressible operon to be transcribed, which of the following must occur?
A) A corepressor must be present.
B) RNA polymerase and the active repressor must be present.
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
D) RNA polymerase must not occupy the promoter, and the repressor must be
inactive. - ANSWERC) RNA polymerase must bind to the promoter, and the
repressor must be inactive.
, Altering patterns of gene expression in prokaryotes would most likely serve an
organism's survival by _____.
A) organizing gene expression, so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing an organism to adjust to changes in environmental conditions
D) allowing environmental changes to alter a prokaryote's genome - ANSWERC)
allowing an organism to adjust to changes in environmental conditions
In positive control of several sugar-metabolism-related operons, the catabolite
activator protein (CAP) binds to DNA to stimulate transcription. What causes an
increase in CAP activity in stimulating transcription?
A) an increase in glucose and an increase in cAMP
B) a decrease in glucose and an increase in cAMP
C) an increase in glucose and a decrease in cAMP
D) a decrease in glucose and a decrease in the repressor - ANSWERB) a decrease
in glucose and an increase in cAMP
There is a mutation in the repressor that results in a molecule known as a super-
repressor because it represses the lac operon permanently. Which of these would
characterize such a mutant?
A) It cannot bind to the operator.
B) It cannot make a functional repressor.
C) It cannot bind to the inducer.
D) It makes a repressor that binds CAP. - ANSWERC) It cannot bind to the inducer.
If she moves the promoter for the lac operon to the region between the beta
galactosidase (lacZ) gene and the permease (lacY) gene, which of the following
would be likely?
A) The three structural genes will be expressed normally.
B) RNA polymerase will no longer transcribe permease.
C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be
translated.
D) Beta galactosidase will not be produced. - ANSWERD) Beta galactosidase will
not be produced.
If she moves the operator to the far end of the operon, past the transacetylase (lacA)
gene, which of the following would likely occur when the cell is exposed to lactose?
A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The structural genes will be transcribed continuously. - ANSWERD) The structural
genes will be transcribed continuously.
If she moves the repressor gene (lacI), along with its promoter, to a position at some
several thousand base pairs away from its normal position, we would expect the
_____.
A) repressor will no longer bind to the operator
B) repressor will no longer bind to the inducer
C) lac operon will be expressed continuously
