BIOL 2500 chapter 14 mc
how many promoters are in an operon
1
in jacob, monod, and pardee's experiment, how many functional copies of lacI were there in the merozygote?
1
what stem loop conformations favor attenuation
1-2 and 3-4
allosteric regulation is accomplished by
a small molecule that fits into a site on the enzyme that is not the active site
an enzyme catalyzes a substrate into a final product. when the conc of the final product is high enough, it binds to a regulatory site o the enzyme. this binding at the regulatory site changes the shape of the enzyme, which prevents it from binding the substrate and prevents formation of more final product. this is an example of
allosteric enzyme
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
antisense RNA does which of the following
binds to the mRNA and prevents translation
operator
cis-acting element
tryptophan
co repressor
allolactose
co-repressor
in jacob, monod, and pardee's experiment, what would have been the conclusion if all four tubes produced a yellow color when b-ONPG was added
expression of the lac operon is constitutive whether lacI is functional or not
DNA that contains instructions for two or more structural genes produces monocistronic mRNA
false
a riboswitch only affects translation of an operon
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
enzymes involved in metabolism are most likely regulated via
feedback inhibition
if a bacteria 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
lac operon
inducible
which of the following encode polycistronic mRNA?
lac operon, trp operon
translational regulatory proteins recognize specific areas of what molecule
mRNA
a mutation in the lacI gene prevents the gene product from binding allolactose. what will the expression level of the operon be in the abscence of lactose?
no transcription
which of the following is an example of post-translational regulation in prokaryotes?
phosphorylation of an enzyme
an activator is present and results in the increase in transcription of the target gene. this is an example of
positive control
regulation of gene expression may occur at which of the following levels?
post translation, translation, transcription
the regulation of protein function is called
posttranslational regulation
in the lac operon, the CAP site is located next to the ___ . when both lactose and glucose are present, this leads to a rate of transcription that is ___.
promoter, low
trp operon
repressible
a gene is inducible and under negative control. which of the following pairs will allow expression of this gene?
repressor and inducer
a deletion in an operon removes the terminator. how will that affect the transcript that is produced from the operon?
the transcript will be produced but longer than normal
a deletion in an operon removes the promoter. how will that affect the transcript that is produced from the operon?
the transcript will not be produced
lacI gene product
trans-acting element
if CAP could not bind to its CAP site, then what would be the result? assume lactose is present
transcription would be difficult to activate in the absence of glucose
what is the gene responsible for attenuation in the trp operon
trpL
constitutive genes are those that have constant levels of expression
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
the regulation of the CAP complex using cAMP is an example of inducible genetic regulation
true
the term enzyme adaptation is used to describe an enzyme that appears in a living cell following exposure to a specific substrate
true
in a particular e.coli strain, a mutation in the thiMD operon results in improper formation of the stem loop secondary structure making it impossible to bind TPP. there are two enzymes encoded by the thiMD operon. how many of the enzymes encoded in the thiMD operon are translated
two