Trp Operon & Lac Operon

Question 1

Organisms cope with environmental fluctuations by exerting what control?

Answer 1

Metabolic control

Question 2

First, cells can vary the number of SPECIFIC enzyme by?

Answer 2

Regulating gene expression

Question 3

Second, cells adjust the activity of enzymes already present - enzymatic regulation for example?

Answer 3

Feedback regulation

Question 4

Is eukaryotic or prokaryotic gene expression regulation more complex?

Answer 4

Eukaryotic gene expression regulation is more complex

Question 5

Who propoesed the operon model for control of bacteria gene expression (used E.coli)?

Answer 5

Jacob and Monod (1961)

Question 6

What 3 elements does the operon contain and describe each?

Answer 6

1. Genes - Genes coding for enzymes of a particular bacterial pathway are clustered together and transcribed as one long mRNA molecule polycistronic mRNA
2. Promoter - Site on DNA template for RNA polymerase binding, it is upstream (5’) to first gene
3. Operator - Short sequence of DNA (between the promoter and genes that it controls) to which the regulatory protein - repressors and activators - bind

Question 7

If tryptophan levels are high, some trp molecules can inhibit first enzyme in pathway – “saves” prescursor material. This is called?

Answer 7

Feedback inhibition

Question 8

Trp operon is responsible for?

Answer 8

The genes that code for SYNTHESIS of Tryptophan