Question 1

Which mechanism of gene regulation allows for the most rapid appearance of activated protein in a prokaryotic cell?

Accepted Answer

Post-translational control

Question 2

A researcher wants to minimize energy and raw material waste in a bacterial cell. Which mechanism of gene regulation should she target?

Accepted Answer

Transcriptional control

Question 3

What is an operon in prokaryotic cells?

Accepted Answer

A region of DNA that codes for a set of genes that are transcribed together as a single mRNA

Question 4

During cellular respiration, ATP binds to phosphofructokinase (PFK) and slows glycolysis. This is an example of which type of gene regulation?

Accepted Answer

Post-translational regulation

Question 5

When lactose levels in E. coli are high, how does this affect expression of the lac operon?

Accepted Answer

Lactose binds to the repressor, causing it to detach from the operator. With the repressor out of the way, RNA polymerase can transcribe the operon.

Question 6

When glucose levels are low in E. coli, what happens to the expression of the lac operon?

Accepted Answer

A regulatory protein is activated by cAMP, causing the protein to bind to a regulatory region associated with the operon, which increases expression of the lac operon.

Question 7

Suppose E. coli cells are exposed to a drug that causes the trp repressor to be permanently bound to tryptophan. What effect would this have on tryptophan synthesis?

Accepted Answer

Tryptophan synthesis would not occur because the repressor would always be bound to the operator and block transcription.

Question 8

An operon in bacteria codes for enzymes involved in synthesizing an amino acid. When the amino acid is abundant, it binds to a regulatory protein that blocks transcription. This is an example of:

Accepted Answer

Negative regulation of transcription because binding of the regulatory protein stops transcription.

Question 9

Global gene regulation in bacteria can involve regulons. What is a regulon?

Accepted Answer

A set of separate genes or operons that contain the same regulatory sequences and are controlled by a single type of regulatory protein.

Question 10

Which hypothetical drug would be most effective at preventing severe diarrhea caused by cholera infection?

Accepted Answer

A drug that binds to the activator protein and prevents it from binding to DNA.

Question 11

In eukaryotic cells, how can a regulatory protein increase gene transcription?

Accepted Answer

It can increase the association of basal transcription factors with the promoter for a gene.

Question 12

Which of the following statements about chromatin modification in eukaryotes is TRUE?

Accepted Answer

DNA is not transcribed when chromatin is packaged tightly in a condensed form.

Question 13

How do eukaryotic cells often turn on a set of genes simultaneously?

Accepted Answer

The genes all have the same regulatory regions associated with them, so an activator protein can turn them all on at once.

Question 14

The diagram shows a segment of DNA and its primary mRNA transcript with exons and introns. What could happen to this mRNA as a result of alternate splicing?

Accepted Answer

The mRNA could contain different sets of exons, for example A-C-E-G-K or A-E-G-K.

Question 15

Which of the following is commonly seen in both prokaryotes and eukaryotes?

Accepted Answer

The activity of the protein coded for by the gene can be regulated to make the protein more or less active.

Question 16

RNA interference allows a eukaryotic cell to ________.

Accepted Answer

Selectively destroy mRNAs that are no longer needed.

Question 17

A researcher finds that cells unable to increase transcription of a gene have deletions 400 bp upstream and in an intron. Could either deletion be responsible?

Accepted Answer

Yes, these deletions could have removed regulatory regions needed to increase transcription.

Question 18

A protein is coded for by a gene. The protein is present in the cell, but its activity is regulated by adding or removing a phosphate group. This is an example of:

Accepted Answer

Post-translational regulation

Question 19

A researcher measures mRNA and protein levels for a gene under two conditions. In condition 2, neither mRNA nor protein is present. What type of regulation is this?

Accepted Answer

Transcriptional regulation

Regulation of Gene Expression in Prokaryotes and Eukaryotes

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