[Lec 7] Mastering Biology: Regulation of Prokaryotic Transcription Flashcards
Which of the following statements best defines the term operon?
a. An operon is a region of DNA that consists of a single gene regulated by more than one promoter.
b. An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.
c. An operon is a region of RNA that consists of the coding regions of more than one gene.
d. An operon is a region of DNA that codes for sugar-metabolizing enzymes.
b.
What molecule binds to promoters in bacteria and transcribes the coding regions of the genes?
a. DNA polymerase
b. A nucleotide
c. RNA polymerase
d. DNA ligase
c.
What is allosteric regulation?
a. In allosteric regulation, a gene is turned off by a repressor protein.
b. In allosteric regulation, a gene is turned on by an activator protein.
c. In allosteric regulation, genes are expressed constitutively.
d. In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.
d.
Under which conditions are the lac structural genes expressed most efficiently?
a. No glucose, high lactose
b. No glucose, no lactose
c. High glucose, high lactose
d. High glucose, no lactose
a.
What happens to the expression of the lacI gene if lactose is not available in the cell?
a. The lacI gene increases its rate of transcription.
b. The lacI gene turns off.
c. There is no change—the lacI gene is constitutively expressed.
d. The lacI gene turns on.
c.
What is the function of the lacZ gene?
a. This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.
b. This gene encodes the repressor of the lac operon.
c. This gene encodes an enzyme, galactoside permease, which transports lactose into the cell.
d. This gene encodes an enzyme, b-galactosidase, that cleaves lactose into two glucose molecules.
a.
Which of the following enzymes converts ATP to cAMP?
a. Adenylyl cyclase
b. ATP synthase
c. Galactoside permease
d. b-galactosidase
a.
True or false? The mechanism by which glucose inhibits expression of the lac structural genes is known as catabolite stimulation, whereas the mechanism by which lactose stimulates expression of thelac structural genes is known as allosteric regulation.
True
False
False.
The operon model of the regulation of gene expression in bacteria was proposed by _____.
a. Watson and Crick
b. Franklin
c. Darwin
d. Jacob and Monod
e. Mendel
d.
Which of these is NOT a component of the lac operon?
a. lactose-utilization genes only
b. promoter only
c. regulatory gene only
d. operator only
e. promoter and operator
c.
Regulatory proteins bind to _____.
a. the operator
b. the lactose-utilization genes
c. the regulatory gene
d. RNA polymerase
e. transcription factors
a.
In the presence of a regulatory protein the lac operon is _____.
a. transcribed
b. not transcribed
c. transcribed at a faster than usual rate
d. is turned on
e. either transcribed or not transcribed
b.
In prokaryotes, when can basal level (constitutive) expression of a gene occur?
a. in the absence of activator and repressor binding
b. only if the expression of the gene is regulated by a repressor
c. only when an activator binds
d. when an activator and repressor bind
a.
