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1. An ___ 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.


2. The ___ is/are arranged sequentially after the promoter.

genes of an operon

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


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

regulatory gene

5. Regulatory proteins bind to the ___ to control expression of the operon.


6. A ___ is a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter.


7. An ___ is a specific small molecule that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.


Which of the following statements best defines the term operon?

An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.

What molecule binds to promoters in bacteria and transcribes the coding regions of the genes?

RNA polymerase

What is allosteric regulation?

In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.

Under which conditions are the lac structural genes expressed most efficiently?

No glucose, high lactose

What happens to the expression of the lacI gene if lactose is not available in the cell?

There is no change—the lacI gene is constitutively expressed.

What is the function of the lacZ gene?

This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.

Which of the following enzymes converts ATP to cAMP?

Adenylyl cyclase

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

Jacob and Monod

Which of these is NOT a component of the lac operon?

regulatory gene only

Regulatory proteins bind to _____.

the operator

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

not transcribed

Which statements about the modification of chromatin structure in eukaryotes are true?

Some forms of chromatin modification can be passed on to future generations of cells. Methylation of histone tails in chromatin can promote condensation of the chromatin. Acetylation of histone tails in chromatin allows access to DNA for transcription. Acetylation of histone tails is a reversible process. DNA is not transcribed when chromatin is packaged tightly in a condensed form.

Which of the following terms describes the DNA-protein complexes that look like beads on a string?


Which of the following regulatory elements is not composed of DNA sequences?


Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene?


Which of the following events in transcription initiation likely occurs last?

RNA polymerase binds to the promoter of the gene.

_____ bind(s) to DNA enhancer regions.


Enzyme complexes that break down protein are called _____.


The nuclear membrane's role in the regulation of gene expression involves _____.

regulating the transport of mRNA to the cytoplasm

What is the function of a spliceosome?

RNA processing

Protein-phosphorylating enzymes' role in the regulation of gene expression involves _____.

protein activation

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