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