Chapter 16: Gene regulation in bacteria

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

1

What stem-loop conformations favor attenuation in the trp operon? -1-2 -1-2 and 2-3 -2-3 -1-2 and 3-4

1-2 and 3-4

Operon

A group of two or more genes under the transcriptional control of a single promoter.

Repressor

A regulatory protein that binds to the DNA and inhibits transcription.

Activator

A regulatory protein that increases the rate of transcription.

Operator

A sequence of bases that provides a binding site for a repressor protein.

Promoter

A sequence of bases that signals the beginning of transcription.

Inducer

A small effector molecule that causes transcription to increase.

Regulation of gene expression may occur at which of the following levels? -transcription -translation -posttranslation -All of the answers are correct.

All of the answers are correct.

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

False

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 repress in the absence of glucose.

Transcription would be difficult to repress in the absence of glucose.

Constitutive genes are those that have constant levels of expression. True or False

True

Coupled transcription and translation occur under conditions in which the tryptophan concentration is very low. True or False

True

In the trp operon, tryptophan is a corepressor. True or False

True

Repressor proteins are responsible for negative transcriptional regulation. True or False

True

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

True

cAMP is a small effector molecule. True or False

True

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 a complementary RNA and prevents its translation -prevents the correct folding of a newly formed peptide

binds to a complementary RNA and prevents its translation

Which of the following is not associated with positive transcriptional regulation? -activators -inducers -corepressors -All of the answers are involved in positive regulation.

corepressors

f a bacterium 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

Translational regulatory proteins recognize specific areas of what molecule? -tRNA -Ribosome -rRNA -mRNA -None of the answers are correct.

mRNA

The lac operon is under what type of control? - positive control -negative control -The gene would be expressed constitutively. -It depends on what the gene encodes.

negative control

Which of the following is not an example of 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

The regulation of protein function, not gene expression is called ______ regulation. -posttranslational -transcriptional -translational -posttranscriptional

posttranslational

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 + corepressor

repressor + inducer

CAP affects which operon(s)? -the lac operon -the trp operon -both the lac and the trp operon -neither the lac nor the trp operon

the lac operon

Riboswitches have been shown to have regulation of ______? -transcription and translation -only transcription -only translation -only RNA splicing

transcription and translation