6.4: lac Operon (SB015)

Multiple Choice

What is occurring in this picture?

• Translation
• DNA Replication
• Polymerase is unzipping the DNA
• Transcription

Multiple Choice

What process is occurring in the diagram?

• Transcription
• Translation
• DNA Replication

• Duplication of ribosomes

Multiple Choice

Operons are found in the cells of which of the following types of organisms?

• Animals

• Bacteria

• Plants

• Viruses

Multiple Choice

lac operon was proposed by ___

• Meselson and Stahl

• Jacob and Monod

• Hershey and Chase

• Watson and Crick

Multiple Choice

What is the purpose of the lac operon?

• to produce lactose

• to inhibit lactose

• to hydrolyze lactose

• to transmit lactose

žThe control of transcription of DNA to mRNA.

žDepends on the role of repressor (protein):

  -- is allosteric

  -- encoded by regulatory gene

  -- Two forms:  Active @ inactive

​What is gene regulation?

Multiple Choice

The lacI gene is transcribed to produce repressor protein. Where does the transcription occur?

• nucleus

• cytoplasm

• ribosome

• nucleolus

Multiple Choice

The "I" letter in gene lacI is derived from ___.

• inducer

• inhibitor

• interphase

• incision

Match

Match the following components of the lac operon with the correct function.

• Operator

• Promoter

• lacZ

• lacY

• lacA

Binding site for repressor protein.

Binding site for RNA polymerase.

Encodes for β-galactosidase.

Encode for permease.

Encode for transacetylase.

• Binding site for repressor protein.

• Binding site for RNA polymerase.

• Encodes for β-galactosidase.

• Encode for permease.

• Encode for transacetylase.

Multiple Choice

Which one is lac operon?

• 1

• 2

• 3

• 4

Multiple Choice

Which of the following is NOT true of the lac operon?

• It contains one regulatory gene that codes for the repressor.

• It contains an inducer, a promoter, and an operator.

• It contains three structural genes.

• The repressor binds to the operator when lactose is absent.

Multiple Choice

How many genes are contained in the lac operon?

• 1

• 2

• 3

• 4

Multiple Choice

Which of these acts as an inducer of the lac operon?

• Allolactose

• Lactose

• Glucose

• Galactose

Multiple Choice

When does transcription of the lac operon stop?

• When the cell has had enough lactose.

• When more lactose is needed.

• When all of the lactose has been broken down.

• When the repressor is absent.

Multiple Choice

The correct option regarding the lac operon in E. coli from the following is

• lac operon is switched on in the absence of lactose.

• Repressor protein binds to the promoter.

• β-galactosidase is the only enzyme produced in large quantities when lac operon is turned on.

• lac operon messenger RNA is a polycistronic mRNA.

Dropdown

When allolactose binds to the repressor of the lac operon, the repressor binds to the operator.
This statement is ​

Select answer

Multiple Choice

In the lac operon, when lactose is present ___

• It will not transcribe and translate to produce β-galactosidase.

• It will transcribe and translate to produce β-galactosidase.

• The repressor is active.

• It will stop all transcription.