Genetics Chapter 14 Test Bank
How many promoters are in an operon?
1
Antisense RNA does which of the following?
Binds to the mRNA and prevents translation
A region of DNA with a single promoter and terminator that contains instructions for two or more structural genes produces monocistronic mRNA.
False
In the lac operon, the operator site is recognized by an activator protein.
False
Negative transcriptional regulation is conducted by activator proteins.
False
If a bacteria is placed in an environment that contains both glucose and lactose, the regulation of the lac operon will allow which nutrient to be processed first?
Glucose
A mutation in the lacl gene prevents the gene product from binding allolactose. What will the expression level of the operon be in the absence of lactose?
No transcription
Which of the following is an example of post translational regulation in prokaryotes?
Phosphorylation of an enzyme with a protein kinase.
A gene is inducible and under negative control. Which of the following pairs will allow expression of this gene?
Repressor + Inducer
Consider an activator/inducer system of regulation in prokaryotes. Which of the following is FALSE?
The active activator binds to the operator of the operon. This is an example of negative control.
Which of the following are TRUE about the lac operon? Choose all that are TRUE.
The lacl repressor protein is inactivated by allolactose binding to the lacl allosteric site. B-galactosidase, an enzyme encoded within the lac operon, catalyzes the conversion of lactose to galactose and glucose, lactose to allolactose and allolactose to galactose and glucose.
A deletion in an operon removes the terminator. How will that affect the transcript that is produced from the operon?
The transcript will be produced, but longer than normal
A deletion in an operon removes the promoter. How will that affect the transcript that is produced from the operon?
The transcript will not be produced
One reason genes are regulated is because it is an energy-savings system. It is wasteful to make proteins and other nutrients if they aren't needed.
True
Regulated genes have variable levels of the gene expression, while constitutive genes are transcribed at constant levels of expression.
True
Repressor proteins are responsible for negative transcriptional regulation
True
The form of regulation that involves a physical change in the shape of an enzyme is called allosteric regulation.
True
Allosteric regulation is accomplished by _______________
a small molecule that fits into a site on the enzyme that is not the active site.
An enzyme catalyzes a substrate into a final product. When the concentration of the final product is high enough, it binds to a regulatory site on the enzyme. This binding at the regulatory site changes the shape of the enzyme, which prevents it from binding the substrate and prevents formation of more final product. This is an example of a(n) ___________.
allosteric enzyme
Enzymes involved in metabolic pathways are most likely regulated via __________.
feedback inhibition
Translational regulatory process such as antisense RNA recognize specific areas of what molecule?
mRNA
An activator is present and results in the increase in transcription of the target gene. This is an example of _______.
positive control
The regulation of a protein's ability to function is called ________.
post-translational regulation
In the lac operon, the CAP site is located next to the _________. When both lactose and glucose are present, this leads to a rate of transcription that is _______.
promoter, low
If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in each scenario.
Transcription would be difficult to activate in the absence of glucose
Constitutive genes are those that have constant levels of expression.
True
In the absence of glucose, cAMP binds to CAP, which allows CAP to bind to the activator region and transcription is activated in the presence of lactose. T/F The regulation of the CAP using cAMP is an example of inducible regulation.
True
