Chapter 14 Genetics Study Guide Questions

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

A) 1

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

A) No transcription

If the Trp codons in the trpL gene were mutated to encode another amino acid, what would the result be? A) The trp operon would never be transcribed. B) The trp operon would always be transcribed. C) The trp operon would only be transcribed when tryptophan in the cell was low. D) The trp operon would only be transcribed when tryptophan in the cell was high.

A) The trp operon would never be transcribed.

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

A) Two

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 whetherlacIis functional or not B)LacIprovides the binding site for the repressor C)LacIencodes a diffusible repressor D)The researcher added too much b-ONPG

A)Expression of the lac operon is constitutive whetherlacIis 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? A)Glucose B)Lactose C)Both will be processed equally D)Neither will be processed in this environment

A)Glucose

Enzymes involved in metabolism are most likely regulated via __________. A)feedback inhibition B)acetylation C)methylation D)None of these choices are correct.

A)feedback inhibition

The regulation of protein function is called __________. A)posttranslational regulation B)transcriptional regulation C)translational regulation D)posttranscriptional regulation

A)posttranslational regulation

What is the gene responsible for attenuation in the trp operon? A)trpL B)trpR C)trpD D)trpC

A)trpL

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

B)1

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

B)Phosphorylation of an enzyme

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/an __________. A)posttranslational modification B)allosteric enzyme C)translational repressor D)methylation

B)allosteric enzyme

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

B)positive control

What would be the result if the U-rich sequence after the 3/4 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

C) 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? 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

C) The transcript will be produced, but longer than normal

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

C)Binds to the mRNA and prevents translation

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

C)Repressor + inducer

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

C)Transcription would be difficult to activate in the absence of glucose

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

C)a small molecule that fits into a site on the enzyme that is not the active site

What stem-loop conformations favor attenuation? A)1-2 B)1-2 and 2-3 C)2-3 D)1-2 and 3-4

D)1-2 and 3-4

Translational regulatory proteins recognize specific areas of what molecule? A)tRNA B)Ribosome C)rRNA D)mRNA

D)mRNA

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

D)promoter; low

You are studying riboswitches in different bacterial strains and you mix up two of your samples! One sample is from E. coli and the other is from B. subtilis. You have an assay in the lab that allows you measure the levels of the enzymes encoded by the thi/thiMD operon (assume the enzymes from the two organisms are similar). Would this assay allow you to distinguish between the two strains? A) Yes - if TPP levels are low and the proteins are produced, the strain is E. coli. B) Yes - if TPP levels are low and the proteins are produced, the strain is B. subtilis. C) Yes - if TPP levels are high and the proteins are produced, the strain is E. coli. D) Yes - if TPP levels are high and the proteins are produced, the strain is B. subtilis. E) No - it would be difficult to distinguish between the strains using this assay.

E) No - it would be difficult to distinguish between the strains using this assay.

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

E)The transcript will not be produced

Which of the following encode polycistronic mRNA? (Check all that apply.) A)Lacoperon B)Operator site C)Trpoperon D)CAP site

Lac operon Trp operon

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

Posttranslation Constitutive expression Translation