Gene expression, Protein Production, and Degradation: Transcription Regulation | Lac Operon

What protein allows lactose to enter the cell?

Lactose permease

The genes that code for the proteins involved in lactose digestion are always “on”, that is to say, continuously being transcribed.

False

When both glucose and lactose are present, the cell would prefer to digest glucose.

True

In what situation would the repressor not be bound to the operators?

When lactose is present

In what scenario would the genes that code for proteins involved in lactose digestion need to be transcribed?

Lacotse present and glucose absent

The binding of the repressor to the operator blocks transcription by:

Twisting the DNA into a loop

Catabolite activator protein is activated by:

cAMP

How many carbon atoms are present in a single glucose molecule?

6

What domain of the repressor protein interacts with the operators?

DNA-binding domains

CAP is a

Homodimer

The repressor protein is composed of:

A dimerization domain, a tetramerization domain, and a DNA-binding domain

What is an operon?

A cluster of genes under the control of a single promoter and transcribed as a single mRNA

How many of the four possible combinations described involve turning on gene transcription for genes that code for proteins involved in lactose digestion?

1

When lactose is present and glucose is absent, the genes that code for proteins involved in lactose digestion would not be transcribed.

False

Any given protein is typically produced:

Only when needed

When glucose is present, the presence or absence of lactose does not matter, with regards to the turning on of genes that code for proteins involved in lactose digestion.

True

The operator is a regulatory region of DNA.

True

Which genes code for proteins involved in lactose import and digestion?

Lac Z, lacY, lacA

What protein cleaves lactose into glucose and galactose?

Beta-galactosidase

The repressor is:

A homotetramer

Binding of CAP to the CAP-binding site promotes:

The recruitment of RNA polymerase to the promoter

Given the choice, which of the following molecules would E. coli prefer to use as the starting point for glucose digestion?

Glucose

In order to efficiently regulate the transcription of genes that code for lactose-digesting proteins, the cell must be able to detect the presence or absence of:

Glucose and lactose

Which of the following proteins is found in the cell membrane?

Lactose permease

For which of the following proteins is its function unclear?

Galactoside acetyltransferase

In the absence of lactose:

A repressor protein binds to operators

Lactose is composed of:

1 glucose molecule and 1 galactose molecule

CAP is an:

Activator of gene transcription

The lac operon contains:

Three operators

When glucose levels are low, intracellular cAMP levels are:

High

The lac operon promoter and regulatory elements are located upstream of the lac operon.

True

When CAP is not bound to the CAP-binding site, RNA polymerase does not bind to the lac operon promoter.

False