ch. 16

contains the sequences of two or more genes

A polycistronic mRNA

the inhibition of the first enzyme in the pathway by the final product of the pathway.

Feedback inhibition frequently involves

promoter

In an operon, the ______ signals the beginning of transcription.

allolactose

The intracellular concentration of the inducer ________ remains high as long as lactose is available in the environment.

Z Y A

the three protein-encoding genes in the lac operon.

cis-acting

A DNA segment that must be adjacent to the gene(s) it regulates is a ___-_____ element.

prevents the repressor from binding to DNA.

Allolactose is a small effector molecule that binds to the lac repressor and

repressor

A regulatory protein that binds to DNA and inhibits transcription is a ____

activator

A regulatory protein that increases the rate of transcription is a(n)

allosteric

A regulatory site on a protein where an effector molecule binds is called a(n) ____ site.

short DNA segments

The CAP site and the operator site are ______ that function in gene regulation.

It probably binds to mRNAs and inhibits translation.

A small RNA is isolated from a bacterial cell. When a comparison is performed between this RNA and other RNAs from this bacterium there are no sequences that match. However, many of the complementary sequences of this short RNA do match other RNAs from the cell. What is the function of this small RNA?

merozygote

A strain of bacteria containing F' factor genes is called a _____ , or a partial diploid.

The lac operon cannot be induced because lactose cannot enter the cell.

If a cell has a mutant lacY gene that produces a non-function product, which of the following statements is true?

glucose

In catabolite repression, transcription is influenced by the presence of

Permease (LacY)

LacY encodes lactose ___

control of proteins already in the cell.

Posttranslational regulation refers to

blocks transcription

The Lac repressor protein binds to the operator and

the protein domain that binds to DNA.

The active site of the lac repressor protein is composed of

posttranslational

The term _____ regulation refers to control of proteins already present in the cell.

glucose decreases

The transport of ______ into a cell causes a _______ in the concentration of cyclic-AMP by inhibiting adenylate cyclase.

adenylyl cyclase

The transport of glucose into a bacterial cell causes the intracellular level of cyclic-AMP to fall because the enzyme __ ___ is inhibited.

1

Transcription of the lac operon results in the production of how many different mRNA transcripts?

lactose

Monod and Jacob studied ____ metabolism in E. coli.

F factor

Monod, Jacob, and Pardee learned about the lac operon using bacterial strains called merozygotes. Since lacI encodes a diffusible protein, in a merozygote, the gene on the __ ____ could supply the mutant cell with functional repressor protein.

allolactose

The binding of ______ to the lac repressor promotes a conformational change that prevents the repressor from binding to the lac operator.

LacZ

The enzyme β-galactosidase is encoded by which gene?

the transport of lactose into the bacterial cell.

The product of the lacY gene is required for

diauxic growth

The sequential use of sugars by a bacterial cell is called __ ___

allolactose

The small effector molecule ___ prevents the lac repressor from binding to the operator site.

catabolite repression

The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose is

onstant levels of expression.

Unregulated genes have ______

the intracellular concentration of allolactose falls.

When lactose is depleted from the environment,

inducible, under negative and positive control

Which of the following best describes regulation of the lac operon?

A cis-acting element must be adjacent to the gene it is regulating.

Why is a merozygote better at complementing a mutation in a trans-acting factor than in a cis-acting element?

trans

Would using a merozygote better indicate regulation of a gene by a trans-acting factor or a cis-acting element?

diauxic growth

Many bacterial species use sugars sequentially. This is called

promoter terminator

The operon is flanked by a ____ that signals the beginning of transcription and a _____ that signals the end of transcription.

polycistronic

An operon encodes a ___ mRNA, an RNA that contains the sequences of two or more genes.

a single promoter

An operon is a group of two or more genes under the transcriptional control of

galactose glucose

The enzyme beta-galactosidase cleaves the sugar lactose into ___ and ___

diffusible protein

The normal lacI gene on the F' factor could rescue the lacI-mutants because the product of the lacI gene encodes a