Control of Gene Expression Quiz Flashcards
Which of the following is NOT a basic concept of gene regulation?
RNAi is required for all genes to be expressed
Not all genes are expressed all of the time
All proteins are encoded by genes
Gene expression makes biochemical sense
RNAi is required for all genes to be expressed
What does methylation of DNA typically do to gene expression?
Recruit RNA polymerase
Induces gene expression
Leads to insulator sequence formation
Transcriptional repression
Activate transcription
Transcriptional repression
In E. coli, what happens to the expression of the trp operon if there is a lot of tryptophan in the cell?
It is turned off, because tryptophan acts as an inducer
It is turned off, because tryptophan acts a corepressor
It is turned on, because tryptophan acts as an inducer
It is turned on, because tryptophan acts a corepressor
There is no change in the expression, it is always the same
It is turned off, because tryptophan acts a corepressor
Genes that are always expressed are called
structural genes
operon genes
repressible genes
constitutively expressed genes
inducible genes
constitutively expressed genes
If there is no glucose and lots of allactose, you would expect the transcriptional output from the lac operon would be :
Relatively high
All of the following are true about glucose and lactose utilization in E. coli, except:
The CAP protein and its effector molecule cAMP exert positive control over the transcription of the lac operon.
High glucose concentrations decrease the intracellular concentration of cAMP, the effector molecule of the CAP protein.
Glucose is preferred over lactose as an energy source for E. coli and is utilized by the bacteria when it is available.
The CAP protein inhibits RNA polymerase from binding to the promoter.
The CAP protein inhibits RNA polymerase from binding to the promoter.
If the lac operator sequence was mutated so that it no longer bound to the lac repressor, which of the following would probably be true?
The bacteria with the mutation would express the genes of the lac operon at very high levels especially in the presence of glucose.
The bacteria with the mutation would NOT express the genes of the lac operon in the absence of allactose.
The bacteria with the mutation would express the genes of the lac operon at very high levels especially in the absence of glucose.
The bacteria with the mutation would NOT express the genes of the lac operon in the presence of allactose.
The bacteria with the mutation would express the genes of the lac operon at very high levels especially in the absence of glucose.
If neither glucose or allactose is present, the transcriptional output from the lac operon would be:
Very, very low (practically nothing)
The lac repressor protein (along with allactose) is an example of:
a negative inducible repressor system
a negative repressible repressor system
a positive inducible activator system
a positive repressible activator system
a negative inducible repressor system
Which of the following is true regarding the lac operon?
If neither CAP and the Lac repressor are binding to the DNA, RNA polymerase will not be able to easily access the promoter
If both CAP and the Lac repressor are binding to the DNA, RNA polymerase will not be able to easily access the promoter
If bound to the operator, the Lac repressor enhances or helps bring RNA polymerase to a promoter
If allactose is present, the Lac repressor binds tightly to DNA
If both CAP and the Lac repressor are binding to the DNA, RNA polymerase will not be able to easily access the promoter
Enhancers work to:
initiate RNA transcription from a promoter by binding to the start site.
increase the amount of translation that occurs from a single mRNA transcript.
degrade mRNA transcripts before translation occurs
increase the level of transcription from a particular promoter
increase the level of transcription from a particular promoter
If a mutation occurred in the promoter for the lacI gene (indicated by the asterisk) that prevented the association of RNA polymerase, which of the following would likely be true:
The bacteria would not be able to metabolize lactose.
The bacteria would express genes for lactose metabolism all the time, especially when no glucose was available.
The bacteria would over-express the lacI gene product, the lac repressor.
The presence of lactose would be lethal to the bacteria
The bacteria would express genes for lactose metabolism all the time, especially when no glucose was available.
If a mutation in the DNA sequence corresponding to the lac operon operator (indicated by the speckles in the picture above) prevented association/binding of the lac repressor, you might expect
enhanced expression of lacZ, but not lacY or lacA
reduced expression of lacZ, and no change to lacY or lacA
reduced expression of lacZ, lacY, and lacA
enhanced expression of lacZ, lacY, and lacA
enhanced expression of lacZ, lacY, and lacA
Changes in the chromatin structure that lead to altered gene expression are called ____________ changes.
repressible
positive
epigenetic
negative
constitutive
Epigenetic
RNAi is involved in
controlling DNA replication by blocking DNA polymerases
preventing translation by binding to the CAP sight of DNA
controlling gene expression by dismantling histone proteins
controlling gene expression by cleaving RNA
controlling transcription by binding to RNA polymerase
controlling gene expression by cleaving RNA
