Gene Regulation

What does an operon consist of?

promoter, operator, and structural genes

What is a promoter?

sequence of DNA-RNA polymerase recognizes and binds

What is an operator?

DNA where regulatory proteins bind

What is upstream?

to the left (beginning) of the promoter

What is downstream?

to the right (after) the promoter

What are two approaches to regulation?

regulation of gene expression and alter activity of enzymes and proteins

How does the regulation of gene expression occur?

transcription initiation, transcription elongation, translation

What is altering activity of enzymes and proteins?

posttranslational

Which domains of life have genome structure and regularly mechanisms?

All three domains of life differ but all have it

How does regulation of transcription initiation occur?

replacement of degraded enzymes

What are constitutive genes?

housekeeping genes that are expressed continuously by the cell

What are inducible genes?

genes that code foe inducible enzymes needed only in certain environments

Where do inducible genes function?

catabolic pathway

When are inducible genes present?

when their substrate (inducer-effector molecule) is available

What is an example of inducible genes?

β-glactosidase reaction catalyzed is lactose hydrolysis into galactose and glucose

What are products of repressible genes?

enzymes that function in biosynthetic pathways

Where are repressible genes present?

generally, always present unless the end product in the biosynthetic pathway is available

What is an example of repressible genes?

enzymes from the trp operon (synthesis of tryptophan)