Molecular Genetics Ch.14 - Learnsmart

how can an inducer cause transcription to increase?

1. it can bind to a repressor protein and prevent it from binding to DNA 2. it can bind to an activator protein and cause it to bind to DNA

CAP site

DNA sequence recognized by an activator protein

A conformational change that prevents the lac repressor from binding to the lac operator occurs when ___________ binds to the lac repressor.

allolactose

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

allolactose

A regulatory site on a protein that is not the active site is called an __________ site.

allosteric

When lactose is depleted from the environment, the _______________.

concentration of intracellular allolactose becomes lower due to the action of metabolic enzymes

When both lactose and glucose are absent, concentrations of cAMP are ____________.

high

When four molecules of allolactose are bound to lac repressor, and repressor can no longer bind to operator, and RNA polymerase is free to transcribe the operon, the operon has been ___________.

induced

negative control

transcriptional regulation by a repressor

induced

a gene that has been transcriptionally activated by an inducer

repressible genes

a gene that is regulated by a corepressor or inhibitor, which are small effector molecules that cause transcription to decrease

inducible genes

a gene that is regulated by an inducer, which is a small effector molecule that causes transcription to increase

operon

a group of two or more genes that are transcribed from a single promoter

an operon encodes what?

a polycistronic mRNA

lac repressor

a protein that binds to the operator site of the lac operon and inhibits transcription

repressor

a regulatory protein that binds to the DNA and inhibits transcription

inducer

a small effector molecule that increases the rate of transcription.

polycistronic mRNA

an RNA that contains the sequences of two or more genes

The small effector molecule produced by the enzyme adenylyl cyclase is ____________.

cAMP

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

catabolite repression

Many bacterial species use sugars sequentially. This is called __________.

diauxic growth

The enzyme beta-galactosidase cleaves the sugar lactose into __________ and ___________.

galactose and glucose

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

glucose ; decrease

how does an effector molecule influence gene expression?

it binds to a regulatory protein and affects its ability to bind DNA

in the absence of allolactose, what happens?

lac repressor is bound to the operator site most of the time

The three protein-encoding genes in the lac operon are ________, ___________, and _________.

lacZ, lacY, and lacA

What is the name for a strain of bacteria containing F' factor?

merozygote

A loss-of-function mutation in a gene encoding a repressor protein has the same effect as a mutation in the __________.

operator site

The lacY gene encodes lactose _______________, a membrane protein.

permease

an operon allows a bacterium to do what?

regulate a group of two or more genes that are involved with a common functional goal: the expression of the genes occurs as a single unit

positive control

regulation by an activator protein

activator

regulatory protein that increases the rate of transcription

enzyme adaptation

the phenomenon in which a particular enzyme appears within a living cell after the cell has been exposed to the substrate for that enzyme

allosteric regulation

the phenomenon in which an effector molecule binds to a noncatalytic site on a protein and causes a conformational change that regulates its function

in bacteria, the most common way to regulate gene expression is by influencing

the rate of transcription initiation

corepressor

a small molecule that binds to a repressor protein, thereby causing the protein to bind to the DNA and it reduces the rate of transcription

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

a trans-acting factor

effector molecules

bind regulatory proteins

inhibitor

binds to an activator protein and prevents it from binding to the DNA and it reduces the rate of transcription

allosteric sites

the site on a protein where a small effector molecule binds to regulate the function of the protein

What type of regulatory element does not need to be adjacent to the gene(s) is it regulating?

trans-acting factor