What does the operon model attempt to explain the coordinated control of gene expression in bacteria bacterial resistance to antibiotics how genes move between homologous regions of DNA the mechanism of viral attachment to a host cell ID: 535245
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Slide1
Regulation of Gene ExpressionSlide2
What does the operon model attempt to explain?
the coordinated control of gene expression
in bacteriabacterial resistance to antibioticshow genes move between homologous regions of DNAthe mechanism of viral attachment to a host cellhorizontal transmission of plant virusesSlide3
What does the operon model attempt to explain?
the coordinated control of gene expression
in bacteriabacterial resistance to antibioticshow genes move between homologous regions of DNAthe mechanism of viral attachment to a host cellhorizontal transmission of plant virusesSlide4
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?
The repressor is active and binds to the operator.
The repressor is inactive, and RNA polymerase moves through the operator.The operator is bound, and mRNA is made.Genes are inactive.
The
corepressor
binds to the repressor.Slide5
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?
The repressor is active and binds to the operator.
The repressor is inactive, and RNA polymerase moves through the operator.The operator is bound, and mRNA is made.
Genes are inactive.
The
corepressor
binds to the repressor.Slide6
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?mutation in lac
(
-
galactosidase
gene)
mutation in
lac
(cannot bind to operator)
mutation in operator (cannot bind to repressor)
mutation in
lac (cannot bind to inducer)Slide7
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?mutation in lac
(
-
galactosidase
gene)
mutation in
lac
(cannot bind to operator)
mutation in operator (cannot bind to repressor)
mutation in
lac (cannot bind to inducer)Slide8
Which element(s) from the following list constitute(s) a bacterial operon?
repressor gene
promoterinducerrepressor proteinall of the aboveSlide9
Which element(s) from the following list constitute(s) a bacterial operon?
repressor gene
promoterinducerrepressor proteinall of the aboveSlide10
Which of the following statements about specific transcription factors is false?
The
binding of specific transcription factors to the control elements of enhancers influences the rate of gene
expression.
Specific
transcription factors include activators and
repressors.
MyoD
is
one.
Some
act indirectly by affecting chromatin
structure.
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.Slide11
Which of the following statements about specific transcription factors is false?
The
binding of specific transcription factors to the control elements of enhancers influences the rate of gene
expression.
Specific
transcription factors include activators and
repressors.
MyoD
is
one.
Some
act indirectly by affecting chromatin
structure.
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.Slide12
Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA?
83%
46%32%13%1.5%Slide13
Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA?
83%
46%32%13%1.5%Slide14
A specific gene is known to code for three different but related proteins. This could be due to which of the following?
premature mRNA degradation
alternative RNA splicinguse of different enhancersprotein degradationdifferential transportSlide15
A specific gene is known to code for three different but related proteins. This could be due to which of the following?
premature mRNA degradation
alternative RNA splicinguse of different enhancersprotein degradationdifferential transportSlide16
RNA is cut up into small 22-nucleotide fragments to regulate another
“target” mRNA. Which of the following is/are true?
The target mRNA is degraded, and its protein is not made.The RNA fragments enhance protein synthesis by
the mRNA.
The RNA fragments bind the ribosome to enhance use of the mRNA and protein synthesis.
The target mRNA is blocked from being used in translation.
The RNA fragments act on the ribosome to shut down translation of all mRNAs.Slide17
RNA is cut up into small 22-nucleotide fragments to regulate another
“target” mRNA. Which of the following is/are true?
The target mRNA is degraded, and its protein is not made.The RNA fragments enhance protein synthesis by
the mRNA.
The RNA fragments bind the ribosome to enhance use of the mRNA and protein synthesis.
The target mRNA is blocked from being used in translation.
The RNA fragments act on the ribosome to shut down translation of all mRNAs.Slide18
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?Specific transcription factors made in the cell determine which genes are expressed.
At fertilization, specific cells are destined for
certain functions.
The activators needed for expression of the
crystallin
gene are present in all cells.
The promoters are different for the different genes.Slide19
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?
Specific transcription factors made in the cell determine which genes are expressed.
At fertilization, specific cells are destined for
certain functions.
The activators needed for expression of the
crystallin
gene are present in all cells.
The promoters are different for the different genes.Slide20
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?cytoplasmic determinantsinductionthe environment around a particular cell
corepressor
proteinsSlide21
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?cytoplasmic determinantsinduction
the environment around a particular cell
corepressor
proteinsSlide22
Initially, cytoplasmic determinants are localized in one part of a zygote and could be which of the following? (Choose more than one answer.)
gene
mRNAtranscription factorribosomemyoblastSlide23
Initially, cytoplasmic determinants are localized in one part of a zygote and could be which of the following? (Choose more than one answer.)
gene
mRNAtranscription factorribosomemyoblastSlide24
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?
Anterior structures would form at both ends.Posterior structures would form at both ends.The embryo would have no dorsal-ventral axis.
Bicoid
mRNA wouldn
’t be translated into protein.Slide25
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?
Anterior structures would form at both ends.Posterior structures would form at both ends.The embryo would have no dorsal-ventral axis.
Bicoid
mRNA wouldn
’t be translated into protein.Slide26
Mutations in _______ genes caused the development of legs in the place of antennae.
homeotic
embryonic lethal myoD Ras
wild-type
Wild type
Eye
MutantSlide27
Mutations in _______ genes caused the development of legs in the place of antennae.
homeotic
embryonic lethal myoD Ras
wild-type
Wild type
Eye
MutantSlide28
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?
certain cells becoming much larger
certain cells shrinkingcertain cells dyingformation of embryonic cellsconcentration of
Bicoid
proteinSlide29
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?
certain cells becoming much larger
certain cells shrinkingcertain cells dyingformation of embryonic cellsconcentration of
Bicoid
proteinSlide30
Which of the following would not typically cause a proto-oncogene to become an oncogene?
gene suppression
translocationamplificationpoint mutationretroviral activationSlide31
Which of the following would not typically cause a proto-oncogene to become an oncogene?
gene suppression
translocationamplificationpoint mutationretroviral activationSlide32
Which of the following statements about the APC gene is false?
It is a tumor-suppressor gene.
It is mutated in 60% of colorectal cancers.It regulates cell migration and adhesion.It may be deleted in colon cancer.Mutations in one allele are enough to lose the gene
’
s function.Slide33
Which of the following statements about the APC gene is
false?
It is a tumor-suppressor gene.It is mutated in 60% of colorectal cancers.It regulates cell migration and adhesion.It may be deleted in colon cancer.Mutations in one allele are enough to lose the gene
’
s function.Slide34
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%).
Scientific Skills ExerciseSlide35Slide36
What was the independent variable in this experiment?
the length of time that the cells were incubated
the relative level of reporter gene mRNAthe distance between the promoter and the enhancerthe possible control element that was deletedSlide37
What was the independent variable in this experiment?
the length of time that the cells were incubated
the relative level of reporter gene mRNAthe distance between the promoter and the enhancerthe possible control element that was deletedSlide38
What was the dependent variable in this experiment?
the length of time that the cells were incubated
how many of the artificial DNA molecules were taken up by the cellsthe relative level of reporter gene mRNAthe distance between the promoter and the enhancerSlide39
What was the dependent variable in this experiment?
the length of time that the cells were incubated
how many of the artificial DNA molecules were taken up by the cellsthe relative level of reporter gene mRNAthe distance between the promoter and the enhancerSlide40
What was the control treatment in this experiment?
the reporter gene
the construct that had no DNA deleted from the enhancerthe temperature, pH, and salt concentration of the incubation mediumthe construct that resulted in the lowest amount of reporter mRNASlide41
What was the control treatment in this experiment?
the reporter gene
the construct that had no DNA deleted from the enhancerthe temperature, pH, and salt concentration of the incubation mediumthe construct that resulted in the lowest amount of reporter mRNASlide42
Do the data suggest that any of these possible control elements are actual control elements?
Only control elements 1 and 2 appear to be control elements.
Only control element 3 appears to be a control element.All three appear to be control elements.None of the possible control elements appear to be actual control elements.Slide43
Do the data suggest that any of these possible control elements are actual control elements?
Only control elements 1 and 2 appear to be control elements.
Only control element 3 appears to be a control element.All three appear to be control elements.None of the possible control elements appear to be actual control elements.Slide44
Did deletion of any of the possible control elements cause a
reduction
in reporter gene expression? How can you tell?Deletion of element 3 caused a reduction in reporter gene expression; that construct resulted in less than 50% of the control level of mRNA.
Deletion of elements 2 and 3 caused a reduction in reporter gene expression; those constructs resulted in less than the highest level of mRNA.
None of the deletions caused a reduction in reporter gene expression; all of them still resulted in reporter mRNA being made.Slide45
Did deletion of any of the possible control elements cause a
reduction
in reporter gene expression? How can you tell?Deletion of element 3 caused a reduction in reporter gene expression; that construct resulted in less than 50% of the control level of mRNA.Deletion of elements 2 and 3 caused a reduction in reporter gene expression; those constructs resulted in less than the highest level of mRNA.
None of the deletions caused a reduction in reporter gene expression; all of them still resulted in reporter mRNA being made.Slide46
If deletion of a control element causes a reduction in gene expression, what must be the normal role of that control element?
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression decreases.To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the
level of gene expression decreases.
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.
To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.Slide47
If deletion of a control element causes a reduction in gene expression, what must be the normal role of that control element?
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression decreases.To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the level of gene expression decreases.
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.
To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.Slide48
Did deletion of any of the possible control elements cause an
increase
in reporter gene expression? How can you tell?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.
Deletion of control element 1 caused an increase in
reporter gene expression; that construct resulted in the highest level of mRNA.
Deletion of control element 3 caused an increase in
reporter gene expression; that construct resulted in less reporter mRNA than the control.
All of the deletions caused an increase in reporter gene expression; all of them still resulted in reporter mRNA being made.Slide49
Did deletion of any of the possible control elements cause an
increase
in reporter gene expression? How can you tell?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.
Deletion of control element 1 caused an increase in
reporter gene expression; that construct resulted in the highest level of mRNA.
Deletion of control element 3 caused an increase in
reporter gene expression; that construct resulted in less reporter mRNA than the control.
All of the deletions caused an increase in reporter gene expression; all of them still resulted in reporter mRNA being made.Slide50
If deletion of a control element causes an increase in gene expression, what must be the normal role of that control element?
To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.To repress gene expression; without the control element, activators are not able to bind to the enhancer, and the
level of gene expression decreases.
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.
To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the
level of gene expression decreases.Slide51
If deletion of a control element causes an increase in gene expression, what must be the normal role of that control element?
To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the
level of gene expression increases.To repress gene expression; without the control element, activators are not able to bind to the enhancer, and the
level of gene expression decreases.
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.
To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the
level of gene expression decreases.