Gene Regulation

how are genes regulated in prokaryotes?

• use operons

• groups of genes are regulated together

• one promoter controls multiple genes (coordinated regulation)

how are genes regulated in eukaryotes?

• don’t use operons

• genes are regulated individually

• use alternative splicing for variety

what is the function of the lac operon?

to break down lactose when it is present

what does the lac operon need in order to break down lactose?

• needs enzyme to break down lactose

• needs transporter to move lactose into cell

what happens to the lac operon when lactose is present?

• lactose binds to repressor

• repressor changes shape and falls off operator

• RNA polymerase binds to promoter and initiates transcription of genes that break down lactose

what happens to the lac operon when lactose is not present?

• repressor binds to operator and blocks RNA polymerase from binding to promoter

• transcription does not occur

• cell saves energy

negative regulation

prevents transcription

positive regulation

activates transcription

what is the role of cAMP during gene regulation?

• produced when cells are low on energy (low glucose levels)

• binds to CAP which helps RNA polymerase bind to promoter better

• helps promote transcription