BIO311: Ch 14 Gene Regulation in Bacteria
True or false: Gene regulation is constant.
False
True or false: The rate of transcription initiation rarely influences overall gene expression.
False
The intracellular concentration of the inducer _________ remains high as long as lactose is available in the environment.
allolactose
A DNA segment that must be adjacent to the gene(s) it regulates is a ________-_______ element
cis-acting
Unregulated genes have ______
constant levels of expression.
When four molecules of allolactose are bound to lac repressor, and repressor can no longer bind to operator, and RNA polymerase is free to transcribe the operon, the operon has been ________ .
induced
An operon __________ encodes a mRNA, an RNA that contains the sequences of two or more genes.
polycistronic
Transcription regulation by an activator protein is considered to be ______ control.
positive
The term _________ regulation refers to control of proteins already present in the cell.
posttranslational
A regulatory protein that inhibits translation is called a ______ _______
translational repressor
True or false: The lac repressor does not completely inhibit transcription of the lacZ, lacY, and lacA genes.
True
An operon is a group of two or more genes under the transcriptional control of ______.
a single promoter
A regulatory protein that increases the rate of transcription is a(n) _________
activator
The transport of glucose into a bacterial cell causes the intracellular level of cyclic-AMP to fall because the enzyme _______ ________ is inhibited
adenyl ; cyclase
When bound to operator, the lac repressor ______.
allows very small amounts of the lac enzymes to be made
When the lac repressor is bound to the operator, RNA polymerase ______ the lacZ, lacY, or lacA genes.
cannot transcribe
The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose is _______ ________
catabolite repression
The sequential use of sugars by a bacterial cell is called ________ ______
diauxic growth
When the product of a gene produced in a metabolic pathway inhibits an enzyme that acts early on in the pathway it is called _____ ______
feedback ; inhibition
The enzyme beta-galactosidase cleaves the sugar lactose into _______ and _________
galactose ; glucose
The transport of ______ into a cell causes a _______ in the concentration of cyclic-AMP by inhibiting adenylate cyclase.
glucose; decrease
When lactose is depleted from the environment, the ______.
intracellular concentration of allolactose falls
The three protein-encoding genes in the lac operon are _______ , ______ , and _______ .
lacZ ; lacY ; lacA
A translational repressor recognizes sequences within ______ and ______ translation.
mRNA; inhibits
What is the name for a strain of bacteria containing an F' factor?
merozygote
A protein such as a repressor that inhibits transcription is exerting ________ control of transcription.
negative
It has been shown that the lac operon has three _______ sites to which the lac repressor can bind.
operator
The research of Jacob and Monod provided ______.
our initial understanding of gene regulation
Allolactose is a small effector molecule that binds to the lac repressor and ______.
prevents repressor from binding to DNA
The operon is flanked by a ________ that signals the beginning of transcription and a __________ that signals the end of transcription.
promoter ; terminator
The phenomenon in which the level of gene expression can vary under different conditions is gene __________ .
regulation
A regulatory protein that binds to DNA and inhibits transcription is a(n) _________ .
repressor
As levels of allolactose increase within an E. coli cell, allolactose binds to the lac _________ , promoting a conformational change that prevents binding to the __________ site on the DNA.
repressor ; operator
In bacteria, the most common way to regulate gene expression is by influencing ______.
the rate of transcription initiation
A polycistronic mRNA contains the sequence(s) ______.
of two or more genes
When the lac repressor binds to the lac _________ site, RNA polymerase cannot transcribe the lacZ, lacY or lacA genes.
operator
