Chapter 18: Regulation of Gene Expression

Question 1

Operator

Answer 1

• In bacterial and phage DNA, sequence of nucleotides near the start of an operon
• An active repressor can attach here
• Binding of the repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon

Question 2

Operon

Answer 2

Unit of genetic function found in bacteria and phages
-Consists of a promoter, an operator, and a coordinately regulated cluster of genes whose products function in a common pathway

Question 3

Repressor

Answer 3

• Protein that inhibits gene transcription
• In prokaryotes, it binds to the DNA in or near the promoter
• In eukaryotes, it may bind to control elements within enhancers, to activators, or to other proteins in a way that blocks activators from binding to DNA

Question 4

Regulatory Gene

Answer 4

• Gene that codes for a protein (i.e. a repressor)

- Controls the transcription of another gene or group of genes

Question 5

Corepressor

Answer 5

• Small molecule
• Binds to a bacterial repressor protein
• Changes a repressor protein’s shape so that it can bind to the operator and switch the operon off

Question 6

Cyclic AMP (cAMP)

Answer 6

• Cyclic adenosine monophosphate
• Ring-shaped molecule made from ATP
• Common intracellular signaling molecule (second messenger) in eukaryotic cells
• Regulator of some bacterial operons

Question 7

Activator

Answer 7

• Protein that binds to DNA and stimulates gene transcription
• In prokaryotes, it binds in or near the promoter
• In eukaryotes, generally bind to elements in enhancers