Deck 14: Gene Regulation in Bacteria

Question 1

If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in each scenario.

A) Transcription would be difficult to repress in the presence of glucose
B) Transcription would be difficult to activate in the presence of glucose
C) Transcription would be difficult to activate in the absence of glucose

Answer 1

C

Question 2

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?

A) Expression of the lac operon is constitutive whether lacI is functional or not
B) LacI provides the binding site for the repressor
C) LacI encodes a diffusible repressor
D) The researcher added too much b-ONPG

Answer 2

A

Question 3

Enzymes involved in metabolism are most likely regulated via ________.

A) feedback inhibition
B) acetylation
C) methylation
D) none of the answers are correct

Answer 3

A

Question 4

A deletion in an operon removes the terminator. How will that affect the transcript that is produced from the operon?

A) The transcript will be produced and normal in length
B) The transcript will be produced, but shorter than normal
C) The transcript will be produced, but longer than normal
D) The transcript will produced, but will contain a deletion
E) The transcript will not be produced

Question 5

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 ________.

A) terminator, low
B) promoter, high
C) terminator, high
D) promoter, low

Question 6

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Inducer

Question 7

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Co-repressor

Question 8

What is the gene responsible for attenuation in the trp operon?

A) trpL
B) trpR
C) trpD
D) trpC

Question 9

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Inducible

Question 10

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?

A) Attenuation would occur if tryptophan was high
B) Attenuation would occur if tryptophan is low
C) Attenuation would not occur if tryptophan was high

Question 11

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Repressible

Question 12

Which of the following is an example of post translational regulation in prokaryotes?

A) Sterically blocking the ribosome
B) Phosphorylation of an enzyme
C) Incorporation of antisense RNA
D) Altering the structure of the mRNA

Question 13

A gene is inducible and under negative control. Which of the following pairs will allow expression of this gene?

A) Activator + repressor
B) Activator + inhibitor
C) Repressor + inducer
D) Repressor + co-repressor

Question 14

How many promoters are in an operon?

A) 1
B) 2
C) 3
D) It depends on how many genes are present in the operon

Question 15

A deletion in an operon removes the promoter. How will that affect the transcript that is produced from the operon?

A) The transcript will be produced and normal in length
B) The transcript will be produced, but shorter than normal
C) The transcript will be produced, but longer than normal
D) The transcript will produced, but will contain a deletion
E) The transcript will not be produced

Question 16

An activator is present and results in the increase in transcription of the target gene. This is an example of ________.

A) termination
B) positive control
C) negative control
D) feedback inhibition

Question 17

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Cis-acting element

Question 18

Allosteric regulation is accomplished by

A) a small molecule that fits into an enzyme's active site.
B) a large protein that blocks an enzyme's active site.
C) a small molecule that fits into a site on the enzyme that is not the active site.
D) a small molecule that covalently modifies a site on the enzyme that is not the active site.

Question 19

What stem-loop conformations favor attenuation?

A) 1-2
B) 1-2 and 2-3
C) 2-3
D) 1-2 and 3-4

Question 20

In Jacob, Monod, and Pardee's experiment, how many functional copies of lacI were there in the merozygote?

A) 0
B) 1
C) 2
D) 3

Question 21

Which of the following encode polycistronic mRNA? Check all that apply.

A) Lac operon
B) operator site
C) Trp operon
D) CAP site

Question 22

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

Question 23

In the lac operon, the operator is an example of a trans-effect genetic regulation.

Question 24

Repressor proteins are responsible for negative transcriptional regulation.

Question 25

Regulation of gene expression may occur at which of the following levels? Check all that apply.

A) post translation
B) constitutive expression
C) translation
D) transcription

Question 26

Translational regulatory proteins recognize specific areas of what molecule?

A) tRNA
B) ribosome
C) rRNA
D) mRNA

Question 27

Operons that code for anabolic enzyme systems are typically regulated by inducers.

Question 28

The term enzyme adaptation is used to describe an enzyme that appears in a living cell following exposure to a specific substrate.

Question 29

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?

A) no transcription
B) positive regulation
C) constitutively active
D) transcription will occur only in the presence of glucose

Question 30

Antisense RNA does which of the following?

A) Inhibits the formation of the open complex in transcription
B) Occupies the A and P sites of the ribosome
C) Binds to the mRNA and prevents translation
D) Prevents the correct folding of a newly formed peptide

Question 31

Operons that code for catabolic enzyme systems are typically regulated by repressors.

Question 32

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

Question 33

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?

A) Glucose
B) Lactose
C) Both will be processed equally
D) Neither will be processed in this environment

Question 34

The regulation of protein function is called ________.

A) posttranslational regulation
B) transcriptional regulation
C) translational regulation
D) posttranscriptional regulation

Question 35

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) ________.

A) posttranslational modification
B) allosteric enzyme
C) translational repressor
D) methylation

Question 36

Constitutive genes are those that have constant levels of expression.

Question 37

Negative transcriptional regulation is conducted by activator proteins.

Question 38

The regulation of the CAP complex using cAMP is an example of inducible genetic regulation.

Question 39

For these questions, match the following to its appropriate letter. Use each letter only once.

A) lacI gene product
B) Operator
C) Allolactose
D) Lac operon
E) Trp operon
F) Tryptophan
Trans-acting element

Question 40

In the lac operon, the operator site is recognized by an activator protein.

Question 41

A riboswitch only affects translation of an operon.

Question 42

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?

A) two
B) zero
C) three
D) one