Chapter 14
What would be the result if the U-rich sequnce after the fourth stem loop in the trp operon was replaced by a UG-rich sequence? -attenuation would occur if tryptophan was high -attenuation would occur if tryptophan was low -attenuation would not occur if tryptophan was high
-attenuation would not occur if tryptophan was high
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 and normal in length -the transcript will be produced but shorter than normal -the transcript will be produced but longer than normal -the transcript will be produced but will contain a deletion -transcript will not be produced
--the transcript will be produced but longer than normal
allosteric regulation is accomplished by: -a small molecule that fits into an enzymes active site -a large protein that blocks an enzyme's active site -a small molecule that fits into a site on the enzyme that is not the active site -a small molecule that covalently modifies a site on the enzyme that is not the active site
-a small molecule that fits into a site on the enzyme that is not the active site
in jacob, monad, 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 lacl is functional or not -lacl provides the binding site for the repressor -lacl encodes a diffusuble repressor -researcher added too much b-ONPG
-expression of the lac operon is constitutive whether lacl is functional or not
How many promoters are in an operon? 1 2 3 depends
1
In Jaciob, Monad, and Pardee's experiment how many functional copies of lacl were there in the merozygote? 0 1 2 3
1
what stem-loop conformations favor attenuation? 1-2 1-2 and 2-3 2-3 1-2 and 3-4
1-2 and 3-4
an enzyme catalyzes a substrate into a final product. When the concentration of the final product is high enough it binds to a regulatory site on the enzyme. This binding at the regulatory site changes the shape of the enzyme, which prevents it form bindingg the substrate and prevents formation of more final product. This is an example of: posttranslational modification allosteric enzyme translational repressor methylation
allosteric enzyme
antisense RNA does which of the following? -inhibits the formation of the open complex in transcription -occupies the A and P sites of the ribosome -binds to the mRNA and prevents translation -prevents the correct folding of a newly formed peptide
binds to the mRNA and prevents translation
DNA that contains instructions for two or more structural genes produces monocistronic mRNA true false
false
In the lac operon the operator is an example of a trans-effect genetic regulation true false
false
a riboswitch only affects translation of an operon true false
false
in the lac operon the operator site is recognized by an activator protein true false
false
negative transcriptional regulation is conducted by activator proteins true false
false
operons that code for anabolic enzyme systems are typically regulated by inducers true false
false
operons that code for catabolic enzyme systems are rtypically regulated by repressors true false
false
enzymes involved in metabolism are most likely regulated via feedback inhibition acetylation methylation none
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 lactose both will be processed equally neither will be processed
glucose
translational regulatory proteins recognize specific areas of what molecule? tRNA ribosome rRNA mRNA
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 absence of lactose? -no transcription -positive regulation -constitutively active -transcription will occur only in the presence of glucose
no transcription
Which of the following is an example of post translational regulation in prokaryotes? -sterically blocking the ribosome -phosphorylation of an enzyme -incorporation of antisense RNA -incorporation of antisense RNA -altering the structure of the mRNA
phosphorylation of an enzyme
An activator is present and results in the increase in transcription of the target gene. This is an example of: termination positive control negative control feedback inhibition
positive control
the regulation of protein function is called: posttranslational regulation transcriptional regulation translational regulation posttranscriptional regulation
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 ___. -terminator, low, -promoter, high -terminator, high -promoter, low
promoter, low
a gene is inducible and under negative control. Which of the following pairs will allow expression of this gene? activator and repressor activator and inhibitor repressor and inducer repressor and corepressor
repressor and inducer
A deletion in an operon removes the promoter. How will that affect the transcript that is produced from the operon? -the transcript will be produced and normal in length -the transcript will be produced but shorter than normal -the transcript will be produced but longer than normal -the transcript will be produced but contain a deletion -transcript will not be produced
transcript will not be produced
If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in each scenario. -transcription would be difficult to repress in the presence of glucose -transcription would be difficult to activate in the presence of glucose -transcription would be difficult to activate in the absence of glucose
transcription would be difficult to activate in the absence of glucose
what is the gene responsible for attenuation in the trp operon? trpL trpR trpD trpC
trpL
Constitutive genes are those that have constant levels of expression true false
true
The form of regulation that involves a physical change in the shape of an enzyme is called allosteric regulation true false
true
repressor proteins are responsible for negative transcriptional regulation true false
true
the regulation of the CAP complex using cAMP is an example of inducible genetic regulation true false
true
the term enzyme adaptation is used to describe an enzyme that appears in a living cell following exposure to a specific substrate true false
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 zero three one
two