lecture 20

What is the role of a repressor in gene expression?

• It activates transcription.

• It inhibits transcription.

• It recruits RNA polymerase.

• It binds to the promoter.

What is the function of an activator in gene expression?

• It inhibits transcription.

• It binds to the operator.

• It induces transcription.

• It dissociates from DNA.

What is the primary reason the metabolism of lactose needs to be regulated in cells?

• Lactose is the only sugar available.

• Breakdown of lactose requires a dedicated enzyme, which is wasteful to produce if not needed.

• Lactose is easier to break down than glucose.

• Lactose does not require any enzymes for breakdown.

Which enzyme is specifically required for the breakdown of lactose?

• Lactase

• β-galactosidase

• Amylase

• Sucrase

In the context of the lac operon, what role does lactose play in E. coli?

• It acts as a repressor.

• It is imported into the cell and used as a carbon source.

• It is exported out of the cell.

• It inhibits the production of glucose.

Where on this slide is a (β1-4) bond?

• Between glucose and galactose in lactose

• Between glucose and fructose in sucrose

• Between two glucose molecules in maltose

• Between two galactose molecules in lactose

What is an operon?

• A group of genes regulated together

• A single gene expressed independently

• A type of RNA molecule

• A protein that binds to DNA

What is the role of the promoter in an operon?

• It binds to transcriptional repressors

• It is the site of RNA polymerase binding

• It enhances the transcription of genes

• It codes for proteins

What are operators in the context of an operon?

• Sites for RNA polymerase binding

• Binding sites for transcriptional repressors

• Genes that code for proteins

• Enhancers of transcription

What is the function of enhancers in an operon?

• They bind to RNA polymerase

• They are binding sites for transcriptional activators

• They code for repressor proteins

• They are involved in DNA replication