CH 16
Riboswitches can regulate
*splicing *translation *transcription *RNA stability
How do a corepressor and an inhibitor differ?
A corepressor binds to a repressor protein, while an inhibitor binds to an activator protein
Proteins binding Catabolite acitivator protein
CAP site
Which processes are regulated at the genetic level
Cell division Response to the environment Metabolism
Gene expression is always the same
False
Gene regulation is constant
False
- researched (with Monod) lactose metabolism in bacteria and established many of the principles of enzyme adaptation
Jacob, Franҫois
determined the crystal structure of lac repressor and confirmed that its structure allows it to bind two operator sites (1996).
Lewis, Mitchell
in the 1950s who studies the lac operon in E. coli.?
Monod, Jacob and Pardee
- researched (with Jacob) lactose metabolism in bacteria and established many of the principles of enzyme adaptation
Monod, Jacques -
Proteins binding Repressor
Operatorq
experimentally determined (with Monod and Jacob) that the lacI gene encodes a repressor protein that is not part of the lac operon.
Pardee, Arthur
If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in this scenario.
Transcription would be difficult to activate in the absence of glucose.
The transport of glucose into a bacterial cell causes the intracellular level of cyclic-AMP to fall because the enzyme ___ ___ is inhibited
adenylyl cyclase
The binding of ___ to the lac repressor promotes a conformational change that prevents the repressor from binding to the lac operator.
allolactose
The binding of _____ to the lac repressor promotes a conformational change that prevents the repressor from binding to the lac operator
allolactose
An enzyme may contain two sites: a catalytic site, and a regulatory or ______ site
allosteric
A regulatory site on a protein where an effector molecule binds is called a
allosteric site
Mutations in the gene for the lac repressor that result in a lac repressor that cannot bind allolactose would mean that transcription from the lac operon is
always repressed
The trp operon is regulated by a repressor and by _____ in which transcription I stopped prematurely
attenuation
Transcription begins but terminates before the entire mRNA is made during
attenuation
Riboswitches may be found in
bacteria, archaea, fungi and plants
The Lac repressor proteins binds to the operator and
blocks transcription
When tryptophan levels are low, the trp repressor ___ bind to the operator site. RNA polymerase ___ transcribe the trp operon.
cannot; can
Induced 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
A DNA segment that must be adjacent to the gene(s) it regulates is a _______-_____ element
cis-acting
Antisense RNA is an RNA strand that is _____to an mRNA molecule
complementary
Unregulated genes are also called
constitutive genes
What type of genes encode proteins the bacteria cell needs all the time
constitutive genes
The product of an operon may act as a _____ if the operon is repressible
corepressor
Genes that are regulated by inducers are called repressible genes.
false
In catabolite repression, transcription is influenced by the presence of
glucose
The transport of ___ into a cell causes a ___ in the concentration of cyclic-AMP by inhibiting adenylate cyclase
glucose; decrease
In feedback inhibition, the final product in a metabolic pathway
inhibits an enzyme that acts early in the pathway
Genetic regulation of translation is usually aimed at preventing the _____ step
initiation
When translation is regulated genetically, which phase of translation is usually blocked?
initiation
The following are protein-encoding genes in the lac operon
lacA, lacY, lacZ
A stain of bacteria containing F (prime ) facto genes is called a ___, or a partial diploid
merozygote
The lac operon is under what type of control?
negative control
A loss-of-function mutation in a gene encoding a repressor has the same effect as a mutation in the
operator site
An ____ is a group of two or more genes under the transcriptional control of a single promoter.
operon
An operon encodes a _____ mRNA, an RNA that contains the sequences of two or more genes
polycistronic
Transcription regulation by an activator is consider to be ___ control
positive
The term_____ regulation refers to control of proteins already present in the cell
posttranslational
Types of _____ covalent modifications include disulfide bond formation and attachment of prosthetic groups
posttranslational
Allolactose is a small effector molecule that binds to the lac repressor and
prevents the repressor from binding to DNA
Proteins binding RNA polymerase
promoter
A regulatory protein that binds to DNA and inhibits transcription is a
repressor
An inducer could bind to an _____ and prevent it from binding to the DNA, or it could bind to a ____ and cause it to bind to the DNA
repressor; activator
an RNA molecule that can exist in two different secondary conformation and thereby affect gene regulation is known as a
riboswitch
A translational repressor protein may bind to the mRNA and
stabilize a secondary structure that prevents translation
When lactose is depleted from the environment,
the intracellular concentration of allolactose falls
The corepressor for a repressible operon may be
the product of that operator
In bacteria, the most common way to regulate gene expression is by influencing
the rate of transcription elongation
The mRNA made form the trpL gene contains codons for 14 amino acids that form
the trp leader peptide
Riboswitches have been shown to have regulation of ______?
transcription and translation
Genes in the trp operon
trpL, trpE, trpD, trpC, trpB, trpA