Question

In a gene regulatory network, describe the differences between: a) Inducible versus Repressible control systems b) Up and Down regulation

Answer 1

Inducible control system. Repressible control system

1. It turns the operon on. 1. It turns the operon off

2 It start trancriptrans and 2 It stop transcription and

Translation. Translation

3.It caused by new metabolite, 3. It is caused by an excess of

which needs enzymes to get existing metabolite.

metabolised.

4.It operates in catabolic pathway. 4. It operates in anabolic pathway.

5.Represser is prevented by the 5. Aporepressor is enabled by a

inducer from joining operator gene. co-repressor to join the operator

gene.

Difference between up and down regulations:-

Up regulation:- if cell increase the number of receptors then it is called as up regulation.

persistently low levels of a hormone can cause its target cells to form additional receptors for that hormone
ex. estrogen causes progesterone to produce more receptors.
ex. insulin up-regulates glucagon.

Down-regulation:- if cell decrease the number of receptors then it is called as down regulation.

prolonged exposure to high hormone concentrations can decrease the # of receptors of that hormone; desensitizes the target cells, so they response less vigoursly to hormonal stimulation, preventing them from overreacting to persistently high hormone levels
ex. progesterone down-regulates estrogen receptors in the uterus.