Transcript File - jj-sct

CAMPBELL
BIOLOGY
TENTH
EDITION
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
18
Regulation of
Gene Expression
Clicker Questions by
Roberta Batorsky
© 2014 Pearson Education, Inc.
What does the operon model attempt to explain?
a) the coordinated control of gene expression
in bacteria
b) bacterial resistance to antibiotics
c) how genes move between homologous regions of
DNA
d) the mechanism of viral attachment to a host cell
e) horizontal transmission of plant viruses
© 2014 Pearson Education, Inc.
What does the operon model attempt to explain?
a) the coordinated control of gene expression
in bacteria
b) bacterial resistance to antibiotics
c) how genes move between homologous regions of
DNA
d) the mechanism of viral attachment to a host cell
e) horizontal transmission of plant viruses
© 2014 Pearson Education, Inc.
When tryptophan (an amino acid) is present in the
external medium, the bacterium brings in the
tryptophan and does not need to make this amino acid.
Which of the following is true when there is no
tryptophan in the medium?
a) The repressor is active and binds to the operator.
b) The repressor is inactive, and RNA polymerase
moves through the operator.
c) The operator is bound, and mRNA is made.
d) Genes are inactive.
e) The corepressor binds to the repressor.
© 2014 Pearson Education, Inc.
When tryptophan (an amino acid) is present in the
external medium, the bacterium brings in the
tryptophan and does not need to make this amino acid.
Which of the following is true when there is no
tryptophan in the medium?
a) The repressor is active and binds to the operator.
b) The repressor is inactive, and RNA polymerase
moves through the operator.
c) The operator is bound, and mRNA is made.
d) Genes are inactive.
e) The corepressor binds to the repressor.
© 2014 Pearson Education, Inc.
Each of a group of bacterial cells has a mutation in its
lac operon. Which of the following will make it
impossible for the cell to metabolize lactose?
a) mutation in lac (-galactosidase gene)
b) mutation in lac (cannot bind to operator)
c) mutation in operator (cannot bind to repressor)
d) mutation in lac (cannot bind to inducer)
© 2014 Pearson Education, Inc.
Each of a group of bacterial cells has a mutation in its
lac operon. Which of the following will make it
impossible for the cell to metabolize lactose?
a) mutation in lac (-galactosidase gene)
b) mutation in lac (cannot bind to operator)
c) mutation in operator (cannot bind to repressor)
d) mutation in lac (cannot bind to inducer)
© 2014 Pearson Education, Inc.
Which element(s) from the following list constitute(s) a
bacterial operon?
a) repressor gene
b) promoter
c) inducer
d) repressor protein
e) all of the above
© 2014 Pearson Education, Inc.
Which element(s) from the following list constitute(s) a
bacterial operon?
a) repressor gene
b) promoter
c) inducer
d) repressor protein
e) all of the above
© 2014 Pearson Education, Inc.
Which of the following statements about specific
transcription factors is false?
a) The binding of specific transcription factors to the control
elements of enhancers influences the rate of gene
expression.
b) Specific transcription factors include activators and
repressors.
c) MyoD is one.
d) Some act indirectly by affecting chromatin structure.
e) Interaction of specific transcription factors and RNA
polymerase II with a promoter leads to a low rate of
initiation and production of a few RNA transcripts.
© 2014 Pearson Education, Inc.
Which of the following statements about specific
transcription factors is false?
a) The binding of specific transcription factors to the control
elements of enhancers influences the rate of gene
expression.
b) Specific transcription factors include activators and
repressors.
c) MyoD is one.
d) Some act indirectly by affecting chromatin structure.
e) Interaction of specific transcription factors and RNA
polymerase II with a promoter leads to a low rate of
initiation and production of a few RNA transcripts.
© 2014 Pearson Education, Inc.
Approximately what proportion of the DNA in the
human genome codes for proteins or functional RNA?
a) 83%
b) 46%
c) 32%
d) 13%
e) 1.5%
© 2014 Pearson Education, Inc.
Approximately what proportion of the DNA in the
human genome codes for proteins or functional RNA?
a) 83%
b) 46%
c) 32%
d) 13%
e) 1.5%
© 2014 Pearson Education, Inc.
A specific gene is known to code for three different but
related proteins. This could be due to which of the
following?
a) premature mRNA degradation
b) alternative RNA splicing
c) use of different enhancers
d) protein degradation
e) differential transport
© 2014 Pearson Education, Inc.
A specific gene is known to code for three different but
related proteins. This could be due to which of the
following?
a) premature mRNA degradation
b) alternative RNA splicing
c) use of different enhancers
d) protein degradation
e) differential transport
© 2014 Pearson Education, Inc.
RNA is cut up into small 22-nucleotide fragments to
regulate another “target” mRNA. Which of the following
is/are true?
a) The target mRNA is degraded, and its protein is
not made.
b) The RNA fragments enhance protein synthesis by
the mRNA.
c) The RNA fragments bind the ribosome to enhance
use of the mRNA and protein synthesis.
d) The target mRNA is blocked from being used in
translation.
e) The RNA fragments act on the ribosome to shut
down translation of all mRNAs.
© 2014 Pearson Education, Inc.
RNA is cut up into small 22-nucleotide fragments to
regulate another “target” mRNA. Which of the following
is/are true?
a) The target mRNA is degraded, and its protein is
not made.
b) The RNA fragments enhance protein synthesis by
the mRNA.
c) The RNA fragments bind the ribosome to enhance
use of the mRNA and protein synthesis.
d) The target mRNA is blocked from being used in
translation.
e) The RNA fragments act on the ribosome to shut
down translation of all mRNAs.
© 2014 Pearson Education, Inc.
Even though the two cells have numerous transcription
factors and many are present in both cells, the lens cell
makes the crystallin protein (not albumin), whereas the
liver cell makes albumin (not crystallin). Which of the
following explains this cell specificity?
a) Specific transcription factors made in the cell
determine which genes are expressed.
b) At fertilization, specific cells are destined for
certain functions.
c) The activators needed for expression of the
crystallin gene are present in all cells.
d) The promoters are different for the different genes.
© 2014 Pearson Education, Inc.
Even though the two cells have numerous transcription
factors and many are present in both cells, the lens cell
makes the crystallin protein (not albumin), whereas the
liver cell makes albumin (not crystallin). Which of the
following explains this cell specificity?
a) Specific transcription factors made in the cell
determine which genes are expressed.
b) At fertilization, specific cells are destined for
certain functions.
c) The activators needed for expression of the
crystallin gene are present in all cells.
d) The promoters are different for the different genes.
© 2014 Pearson Education, Inc.
Differential gene expression (different genes turned on
in different cells) leads to different tissues developing in
the embryo. Which of the following is not a cause of
differential gene expression?
a) cytoplasmic determinants
b) induction
c) the environment around a particular cell
d) corepressor proteins
© 2014 Pearson Education, Inc.
Differential gene expression (different genes turned on
in different cells) leads to different tissues developing in
the embryo. Which of the following is not a cause of
differential gene expression?
a) cytoplasmic determinants
b) induction
c) the environment around a particular cell
d) corepressor proteins
© 2014 Pearson Education, Inc.
Initially, cytoplasmic determinants are localized in one
part of a zygote and could be which of the following?
(Choose more than one answer.)
a) gene
b) mRNA
c) transcription factor
d) ribosome
e) myoblast
© 2014 Pearson Education, Inc.
Initially, cytoplasmic determinants are localized in one
part of a zygote and could be which of the following?
(Choose more than one answer.)
a) gene
b) mRNA
c) transcription factor
d) ribosome
e) myoblast
© 2014 Pearson Education, Inc.
Scientists showed that bicoid mRNA, and then its
Bicoid protein, is normally found in highest
concentrations in the fly’s anterior. What would happen
if Bicoid were injected at the posterior end?
a) Anterior structures would form at both ends.
b) Posterior structures would form at both ends.
c) The embryo would have no dorsal-ventral axis.
d) Bicoid mRNA wouldn’t be translated into protein.
© 2014 Pearson Education, Inc.
Scientists showed that bicoid mRNA, and then its
Bicoid protein, is normally found in highest
concentrations in the fly’s anterior. What would happen
if Bicoid were injected at the posterior end?
a) Anterior structures would form at both ends.
b) Posterior structures would form at both ends.
c) The embryo would have no dorsal-ventral axis.
d) Bicoid mRNA wouldn’t be translated into protein.
© 2014 Pearson Education, Inc.
Mutations in _______ genes caused the development
of legs in the place of antennae.
a) homeotic
b) embryonic lethal
c) myoD
Wild type
d) Ras
Eye
e) wild-type
© 2014 Pearson Education, Inc.
Mutant
Mutations in _______ genes caused the development
of legs in the place of antennae.
a) homeotic
b) embryonic lethal
c) myoD
Wild type
d) Ras
Eye
e) wild-type
© 2014 Pearson Education, Inc.
Mutant
The shape of an organ, the number of brain cells in an
embryonic brain, the removal of mutated cells, and the
webbing cells between the toes of a human embryo are
all regulated by which of the following?
a) certain cells becoming much larger
b) certain cells shrinking
c) certain cells dying
d) formation of embryonic cells
e) concentration of Bicoid protein
© 2014 Pearson Education, Inc.
The shape of an organ, the number of brain cells in an
embryonic brain, the removal of mutated cells, and the
webbing cells between the toes of a human embryo are
all regulated by which of the following?
a) certain cells becoming much larger
b) certain cells shrinking
c) certain cells dying
d) formation of embryonic cells
e) concentration of Bicoid protein
© 2014 Pearson Education, Inc.
Which of the following would not typically cause a
proto-oncogene to become an oncogene?
a) gene suppression
b) translocation
c) amplification
d) point mutation
e) retroviral activation
© 2014 Pearson Education, Inc.
Which of the following would not typically cause a
proto-oncogene to become an oncogene?
a) gene suppression
b) translocation
c) amplification
d) point mutation
e) retroviral activation
© 2014 Pearson Education, Inc.
Which of the following statements about the APC gene
is false?
a) It is a tumor-suppressor gene.
b) It is mutated in 60% of colorectal cancers.
c) It regulates cell migration and adhesion.
d) It may be deleted in colon cancer.
e) Mutations in one allele are enough to lose the
gene’s function.
© 2014 Pearson Education, Inc.
Which of the following statements about the APC gene
is false?
a) It is a tumor-suppressor gene.
b) It is mutated in 60% of colorectal cancers.
c) It regulates cell migration and adhesion.
d) It may be deleted in colon cancer.
e) Mutations in one allele are enough to lose the
gene’s function.
© 2014 Pearson Education, Inc.
Scientific Skills Exercise
The diagrams on the next slide show an intact DNA
sequence (top) and three experimental DNA sequences. A
red X indicates the possible control element (1, 2, or 3) that
was deleted in each experimental DNA sequence. The area
between the slashes represents the approximately 8
kilobases of DNA located between the promoter and the
enhancer region. The horizontal bar graph shows the
amount of reporter gene mRNA that was present in each
cell culture after 48 hours relative to the amount that was in
the culture containing the intact enhancer region (top bar =
100%).
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
What was the independent variable in this experiment?
a) the length of time that the cells were incubated
b) the relative level of reporter gene mRNA
c) the distance between the promoter and the
enhancer
d) the possible control element that was deleted
© 2014 Pearson Education, Inc.
What was the independent variable in this experiment?
a) the length of time that the cells were incubated
b) the relative level of reporter gene mRNA
c) the distance between the promoter and the
enhancer
d) the possible control element that was deleted
© 2014 Pearson Education, Inc.
What was the dependent variable in this experiment?
a) the length of time that the cells were incubated
b) how many of the artificial DNA molecules were taken
up by the cells
c) the relative level of reporter gene mRNA
d) the distance between the promoter and the
enhancer
© 2014 Pearson Education, Inc.
What was the dependent variable in this experiment?
a) the length of time that the cells were incubated
b) how many of the artificial DNA molecules were taken
up by the cells
c) the relative level of reporter gene mRNA
d) the distance between the promoter and the
enhancer
© 2014 Pearson Education, Inc.
What was the control treatment in this experiment?
a) the reporter gene
b) the construct that had no DNA deleted from the
enhancer
c) the temperature, pH, and salt concentration of the
incubation medium
d) the construct that resulted in the lowest amount of
reporter mRNA
© 2014 Pearson Education, Inc.
What was the control treatment in this experiment?
a) the reporter gene
b) the construct that had no DNA deleted from the
enhancer
c) the temperature, pH, and salt concentration of the
incubation medium
d) the construct that resulted in the lowest amount of
reporter mRNA
© 2014 Pearson Education, Inc.
Do the data suggest that any of these possible control
elements are actual control elements?
a) Only control elements 1 and 2 appear to be control
elements.
b) Only control element 3 appears to be a control
element.
c) All three appear to be control elements.
d) None of the possible control elements appear to be
actual control elements.
© 2014 Pearson Education, Inc.
Do the data suggest that any of these possible control
elements are actual control elements?
a) Only control elements 1 and 2 appear to be control
elements.
b) Only control element 3 appears to be a control
element.
c) All three appear to be control elements.
d) None of the possible control elements appear to be
actual control elements.
© 2014 Pearson Education, Inc.
Did deletion of any of the possible control elements
cause a reduction in reporter gene expression? How
can you tell?
a) Deletion of element 3 caused a reduction in
reporter gene expression; that construct resulted
in less than 50% of the control level of mRNA.
b) Deletion of elements 2 and 3 caused a reduction in
reporter gene expression; those constructs resulted
in less than the highest level of mRNA.
c) None of the deletions caused a reduction in reporter
gene expression; all of them still resulted in reporter
mRNA being made.
© 2014 Pearson Education, Inc.
Did deletion of any of the possible control elements
cause a reduction in reporter gene expression? How
can you tell?
a) Deletion of element 3 caused a reduction in
reporter gene expression; that construct resulted
in less than 50% of the control level of mRNA.
b) Deletion of elements 2 and 3 caused a reduction in
reporter gene expression; those constructs resulted
in less than the highest level of mRNA.
c) None of the deletions caused a reduction in reporter
gene expression; all of them still resulted in reporter
mRNA being made.
© 2014 Pearson Education, Inc.
If deletion of a control element causes a reduction in gene
expression, what must be the normal role of that control
element?
a) To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression decreases.
b) To activate gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
c)
To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
d) To activate gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
© 2014 Pearson Education, Inc.
If deletion of a control element causes a reduction in gene
expression, what must be the normal role of that control
element?
a) To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression decreases.
b) To activate gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
c)
To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
d) To activate gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
© 2014 Pearson Education, Inc.
Did deletion of any of the possible control elements cause
an increase in reporter gene expression? How can you tell?
a) Deletion of control element 1 or 2 caused an increase
in reporter gene expression; both constructs resulted in
over 100% of the control level of mRNA.
b) Deletion of control element 1 caused an increase in
reporter gene expression; that construct resulted in the
highest level of mRNA.
c)
Deletion of control element 3 caused an increase in
reporter gene expression; that construct resulted in less
reporter mRNA than the control.
d) All of the deletions caused an increase in reporter gene
expression; all of them still resulted in reporter mRNA being
made.
© 2014 Pearson Education, Inc.
Did deletion of any of the possible control elements cause
an increase in reporter gene expression? How can you tell?
a) Deletion of control element 1 or 2 caused an increase
in reporter gene expression; both constructs resulted in
over 100% of the control level of mRNA.
b) Deletion of control element 1 caused an increase in
reporter gene expression; that construct resulted in the
highest level of mRNA.
c)
Deletion of control element 3 caused an increase in
reporter gene expression; that construct resulted in less
reporter mRNA than the control.
d) All of the deletions caused an increase in reporter gene
expression; all of them still resulted in reporter mRNA being
made.
© 2014 Pearson Education, Inc.
If deletion of a control element causes an increase in gene
expression, what must be the normal role of that control
element?
a) To activate gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
b) To repress gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
c)
To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
d) To activate gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
© 2014 Pearson Education, Inc.
If deletion of a control element causes an increase in gene
expression, what must be the normal role of that control
element?
a) To activate gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
b) To repress gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
c) To repress gene expression; without the control element,
repressors are not able to bind to the enhancer, and the
level of gene expression increases.
d) To activate gene expression; without the control element,
activators are not able to bind to the enhancer, and the
level of gene expression decreases.
© 2014 Pearson Education, Inc.