Bio Ch 18: Prokaryotic Gene Regulation

Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?

Although the expression of most genes is tightly regulated, some genes are expressed at roughly constant rates. Which of the following genes would you predict to be constitutively (constantly) expressed? a. genes involved in the degradation of tryptophan b. genes that code for regulatory proteins c. genes involved in the degradation of arabinose, a sugar d. genes involved in the biosynthesis of the amino acid tryptophan

The greatest expression of the lac operon occurs when lactose levels are _____.

On what sequence of DNA does the lac repressor bind?

Why is glucose the preferred energy source?

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator? a. ubiquitin b. inducer c. repressor d. promoter e. corepressor

An E. coli cell without a functional lacI gene is expected to _____.

The operon model of the regulation of gene expression in bacteria was proposed by _____.

Which of these is NOT a component of the lac operon? a. lactose-utilization genes only b. promoter only c. regulatory gene only d. operator only e. promoter and operator

Regulatory proteins bind to _____.

In the presence of a regulatory protein the lac operon is _____.

The product of the lacI gene functions most like a car's _____.

Jacob and Monod were intellectually primed to draw the conclusions they did concerning regulation of the lac operon. In part, this was due to their fascination with mechanisms of enzyme regulation. They knew that the activity of some enzymes is regulated when their reaction product binds to the enzyme, changing its shape and, therefore, its activity. This knowledge allowed them to easily make the intellectual leap to propose _____.

According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?

The product of the lacI gene is _____.

Which of the following is a protein produced by a regulatory gene? a. repressor b. corepressor c. operon d. promoter e. inducer

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation? a. inducer b. promoter c. cAMP d. RNA polymerase e. transcription factor

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is exposed to lactose?

How does the negative control of the lac operon by glucose function through inducer exclusion?

The presence of a mutant lac repressor that could not bind lactose would result in _______ transcription even when lactose was present because the mutant repressor would remain bound to the lac __________

High glucose levels decrease activity of the galactoside permease transporter. When lactose and glucose levels are high outside the cell, what will be the effect on lactose transport?

When the lac repressor protein binds to lactose, why does it fall off its binding site at the operator?

Regulation of the lac operon by the CAP protein is an example of gene regulation at what level?

A(n) ... is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway.

the ... is/are arranged sequentially after the promoter.

A(n) ... is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.

a ... codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes

Regulatory proteins often bind to the ... to control expression of the operon.

A(n) ... is a protein that inhibits gene transcription. In bacteria, this protein binds to the DNA in or near the promoter

A(n) ... is a specific small molecule that binds to a bacterial repressor protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.

Under what condition is the AraC protein an activator?

One interesting and surprising finding regarding the regulation of the ara operon is that it is under both positive and negative control. What protein is responsible for the dual action of this operon?

Regarding regulation of the ara operon, what would be the effect of a mutation that removes the part of the AraC protein that binds to RNA Polymerase?

When arabinose is absent, how will the AraC protein dimer interact with the arabinose operon region?