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Biology Chapter 18: Control of Gene Expression Prokaryotic
Terms in this set (23)
the three modes of gene regulation which is the fastest in response time?
Because this mode involves modification of an already synthesized protein, it is the fastest in terms of regulating the activity of the gene product.
the three modes of gene regulatio, which is the most efficient in resource use?
Transcriptional control can stop gene expression at the earliest possible step, saving the most energy and materials for the cell.
On what sequence of DNA does the lac repressor bind?
Operator of lac operon
This prevents the stable association of the RNA polymerase with the lac promoter
How would decreasing the stability of an mRNA impact the amount of protein encoded by that mRNA?
Fewer proteins will be produced by that mRNA.
Why is glucose the preferred energy source?
Glucose is the input for glycolysis and cellular respiration.
Glucose can by used for glycolysis directly.
Under conditions of high glucose and high lactose concentrations, what will happen to the levels of β-galactosidase?
Essentially no β-galactosidase will be produced.
Even though lactose is an inducer for β-galactosidase, the enzyme is not produced if glucose is present.
Which of these is NOT a component of the lac operon?
regulatory gene only
The regulatory gene, while not a part of the operon, plays a role in regulating the expression of the genes of the operon.
Regulatory LacI protein binds to _____.
Transcription is inhibited when a regulatory protein binds to the lac operon operator.
In the presence of lacI protein, the lac operon is _____.
The regulatory protein of the lac operon is a repressor.
If the binding of the CAP-cAMP complex promotes transcription of the induced lac operon, then how does the negative control of the lac operon by glucose function through the CAP-cAMP complex?
When glucose concentration is high, the concentration of cAMP and the complex are low.
When the complex concentration is low, transcription is not promoted.
How does the negative control of the lac operon by glucose function through inducer exclusion?
High glucose concentrations prevent the transport of lactose into the cell.
If lactose is excluded from the cell, the lac operon cannot be induced.
The presence of a mutant lac repressor that could not bind lactose would result in _______ transcription even when lactose was present because the mutant repressor would remain bound to the lac __________
Since the operator is occupied with the repressor, the RNA polymerase cannot bind and transcribe these genes even when lactose is present.
How many types of mRNA are transcribed from the lac operon?
The single promoter is used to initiate transcription of a single mRNA that encodes the lacZ, lacY, and lacA proteins.
When the lac repressor protein binds to lactose, why does it fall off its binding site at the operator?
When bound to lactose, the LacI protein changes its shape
Regulation of the lac operon by the CAP protein is an example of gene regulation at what level?
When cAMP levels are low, CAP does not bind the lac promoter to activate transcription.
In the lac operon, the repressor inhibits transcription when....
the repressor is not bound to the inducer.
A(n) ____________ is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway.
The _________________ is/are arranged sequentially after the promoter.
genes of an operon
A(n) ____________ is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
A(n) _________________ codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
Regulatory proteins often bind to the _________ to control expression of the operon.
A(n) ____________ is a protein that inhibits gene transcription. In bacteria, this protein binds to the DNA in or near the promoter.
A(n) ______________ is a specific small molecule that binds to a bacterial repressor protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.
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