Genetics Ch. 16
The term enzyme adaptation is used to describe an enzyme that appears in a living cell following exposure to a specific substrate.
True
cAMP is a small effector molecule.
True
How many promoters are in an operon?
1
In Jacob, Monod, and Pardee's experiment, how many functional copies of lacl were there in the merozygote?
1
What stem-loop conformations favor attenuation?
1-2 and 3-4
For these questions, match the following to its appropriate letter. Use each letter only once. 1) Cis-mutation 2) Trans-mutation 3) Inducer 4) Corepressor 5) Repressible 6) Inducible
5) Trp operon 3) Allolactose 1) Operator 6) Lac operon 2) Lacl 4) Tryptophan
Regulation of gene expression may occur at which of the following levels?
All of the answers are correct.
Which of the following encode polycistronic mRNA?
All of the answers are correct.
Which of the following is found in an operon?
All of the answers are correct.
What would be the result if the U-rich sequence after the fourth stem loop in the trp operon was replaced by a UG-rich sequence?
Attenuation would not occur if tryptophan was high.
In the Jacob Monod merozygote experiment, what was indicated by the presence of a yellow color when b-ONPG was added?
Beta-galactosidase was present.
Because it stabilizes mRNA, antisense RNA enhances translation.
False
DNA that contains instructions for two or more structural genes produces monocistronic mRNA.
False
In the lac operon, the operator is an example of a trans-effect genetic regulation.
False
In the lac operon, the operator site is recognized by an activator protein.
False
Negative transcriptional regulation is conducted by activator proteins.
False
Operons that code for anabolic enzyme systems are typically regulated by inducers.
False
Operons that code for catabolic enzyme systems are typically regulated by repressors.
False
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.
A riboswitch is an RNA molecule that can exist in two different conformations. Conversion from one to another is due to the binding of a small molecule to the riboswitch.
True
Constitutive genes are those that have constant levels of expression.
True
Coupled transcription and translation occur under conditions in which the tryptophan concentration is very low.
True
In the E. coli riboswitch, mRNA gets translated when TPP is low.
True
In the trp operon, tryptophan is a corepressor.
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.
Antisense RNA does which of the following?
binds to the mRNA and prevents translation.
Which of the following is not associated with positive transcriptional regulation?
corepressors
Enzymes involved in metabolism are most likely regulated via ________.
feedback inhibition
If a bacterium 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
Translational regulatory proteins recognize specific areas of what molecule?
mRNA
The lac operon is under what type of control?
negative control
Which of the following is not an example of translational regulation in prokaryotes?
phosphorylation of an enzyme
The regulation of protein function, not gene-expression is called ______ regulation.
posttranslational
A gene is inducible and under negative control. Which of the following pairs will allow expression of this gene?
repressor + inducer
CAP affects which operon(s)?
the lac operon
Riboswitches have been shown to have regulation of ___________?
transcription and translation
What is the gene responsible for attenuation in the trp operon?
trpL
