BIO 140 CH. 14 Connect CONCEPTS
In the trpL gene, which stem-loop together with the U-rich attenuator sequence acts as an intrinsic terminator
3-4
An operon is a group of two or more genes under the transcriptional control of
A single promoter
What happens when levels of allolactose rise inside an E. Coli cell?
Allolactose binds to the lac repressor and prevents it from binding to the operator.
T/F: Gene expression is always the same
False
T/F: The rate of transcription initiation rarely influences overall gene expression
False
The trp operon is regulated by a repressor protein and by ______ in which transcription is stopped prematurely
attenuation
Transcription begins but terminates before the entire mRNA is made during ________
attenuation
The conversion of a riboswitch form one conformation to another is due to
binding of a small molecule
During attenuation, transcription begins
but it is terminated before the entire mRNA is made
When the lac repressor is bound to the operator, RNA polymerase _______ the lacZ, lacY, or lacA genes
cannot transcribe
Inducible operons usually encode ______ enzymes, and repressible operons usually encode _________ enzymes
catabolic; anabolic
The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose is ___________ __________.
catabolite repression
Posttranslational regulation refers to ____________-
control of proteins already in the cell
In catabolite repression, transcription is influenced by the presence of _______
glucose
In feedback inhibition, the final product in a metabolic pathway ________
inhibits an enzyme that acts early in the pathway
An operon encodes a _____ mRNA, an RNA that contains the sequences of two or more genes
polycistronic
The term ________ regulation refers to control of proteins already present in the cell.
posttranslational
In the thi operon, when the levels of TPP are low, the mRNA folds into a stem-loop structure that
prevents formation of the terminator stem-loop
Phenomenon in which the level of gene expression can vary under different conditions is gene
regulation
When lactose is depleted from the environment, the
Intracellular concentration of allolactose fails
A polycistronic mRNA contains the sequence(s)
of 2+ genes
In the trpl sequence, the 3-4 stem-loop together with the U-rich attenuator sequence acts as a(n) ___________ ____________
intrinsic sequence
In the trpL gene, the 3-4 stem-loop together with the U-rich attenuator sequence acts as an _________________ ________________
intrinsic terminator
When the tryptophan level in the cell is _______, the ribosome pauses in region one of the trpL mRNA, causing region 2 to bind to region 3 and transcription to continue.
low
A translational repressor recognizes sequences within _______ and _____ translation
mRNA; inhibits
It has been shown that the lac operon has three _________ sites to which the lac repressor can bind
operator
When the lac repressor binds to the lac _____ site, RNA polymerase cannot transcribe the lacZ, lacY, or lacA genes
operator
An _______ is a group of two or more genes under the transcriptional control of a single promoter
operon
The research of Jacob and Monod provided
our initial understanding of gene regulation
An RNA molecule that can exist in two different secondary conformations and thereby affect gene regulation is known as a(n) ___________
riboswitch
In bacteria, the most common way to regulate gene expression is by influencing
the rate of transcription regulation
Riboswitches can regulate
transcription or translation
The TPP riboswitch in E.coli controls _______, whereas the TPP riboswitch in B. sutilis controls ______
translation; transcription
Why does transcription of the trp operon continue when tryptophan levels are low?
The ribosome pauses in region 1, preventing the 3-4 stem-loop from forming
The intracellular concentration of the inducer ____ remains high as long as lactose is available in environment
allolactose
In the thi operon, when levels of TPP are low, the 5' end of the mRNA forms an __________ stem-loop structure that allows transcription to continue
antiterminator
Anabolic enzymes are usually encoded by ______ operons, and _________ operons usually encode catabolic enzymes
repressible; inducible
Studies indicate that the lac operon has ____ operator site(s) for the lac repressor
three
The research of Monod and Jacob that led to the initial understanding of gene regulation stemmed from an interest in
enzyme adaptation
The genes in the trp operon encode
enzymes used in tryptophan biosynthesis
As levels of allolactose increase within an E. coli cell, allolactose binds to the lac _________, promoting a conformational change that prevents binds to the _______site on the DNA
repressor, operator
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
In attenuation, transcription
is stopped prematurely
A regulatory protein that inhibits translation is called a __________ ________
translational repressors
Select the genes in the trp operon
trpE, trpD, trpC, trpB, and trpA,