Chapter 14

How many promoters are in an operon? 1 2 3 It depends on how many genes are present in the operon

1

In Jacob, Monod, and Pardee's experiment, how many functional copies of lacI 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

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 occur if tryptophan was high Attenuation would occur if tryptophan is low Attenuation would not occur if tryptophan was high

Attenuation would not occur if tryptophan was high

Antisense RNA does which of the following? (A) occupies the A&P sites of the ribosome (B) inhibits the formation of the open complex in transcription (C) binds to the mRNA & prevents translation (D) prevents the correct folding of a newly formed peptide

Binds to the mRNA and prevents translation

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 LacI provides the binding site for the repressor LacI encodes a diffusible repressor The researcher added too much b-ONPG

Expression of the lac operon is constitutive whether lacI is functional or not

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 in this environment

Glucose

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 Altering the structure of the mRNA

Phosphorylation of an enzyme

A gene is inducible and under negative control. Which of the following pairs will allow expression of this gene? Activator + repressor Activator + inhibitor Repressor + inducer Repressor + co-repressor

Repressor + 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 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 produced, but will contain a deletion The transcript will not be produced

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 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 produced, but will contain a deletion The transcript will not be produced

The 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

Allosteric regulation is accomplished by a small molecule that fits into an enzyme's 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.

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 from binding the substrate and prevents formation of more final product. This is an example of a(n) _______________. posttranslational modification allosteric enzyme translational repressor methylation

allosteric enzyme

A riboswitch only affects translation of an operon.

false

DNA that contains instructions for two or more structural genes produces monocistronic mRNA.

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 acetylation methylation none of the answers are correct

feedback inhibition

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

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

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

The form of regulation that involves a physical change in the shape of an enzyme is called allosteric regulation. true or false

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 zero three one

two

Repressor proteins are responsible for negative transcriptional regulation.

true