Chapter 14 - Induction and Catabolite Repression Lab Quiz

Genes control

The synthesis of proteins and enzymes

To conserve energy if an enzyme is not needed

The gene may be “turned off”

Substrate

A molecule that reacts with an enzyme

Catabolite

A substrate used as an energy source by the cell; large complex molecule

Constitutive enzyme

An enzyme that is continually produced by the cell

Inducible enzyme

an enzyme produced only when appropriate substrate is present

Transcription

the first step in the process by which the information in the genetic code results in the manufacture of a protein. Transcription is followed by translation.

Beta-galactosidase

Breaks down lactose

Beta-galactosidase cuts the lactose down into

Glucose and galactose

What happens in absence of lactose?

Repressor molecule binds to the promotor gene. RNA polymerase cannot attach; b-galactosidase is not made

What happens when lactose is present?

Lactose binds to repressor, RNA polymerase binds to promotor and operator gene is switched on, enzyme starts production

Starch

a large molecule or catabolite which must be broken down before it can enter the cell

Amylase

The exoenzyme that breaks down starch and is secreted outside the cell so it can break down starch in the environment

Starch + iodine on agar plate =

purple color

If starch is not present

iodine will not bind to agar and there will be a clear area