2

In ar nv ciiva«

Rc|)i<-vu>r-

blocking

promotor

Regulatory region		Gcnc
		□	V
		Signal motcculc	Signal molecule

Gcnc

FIGURĘ 9.09 Principle of Positive and Negative Regulation

In positive regulation, a signal cbanges tbe conformation of an inactive regulator, which tben becomes active and bind$ to tbe regulatory region of a gene. Its presence aids tbe birtding of tbe RNA polymerase and belps switcb on tbe gene. In negative regulation, a repressor molecule błocks tbe promołer of tbe gene. A signal cbanges tbe conformation of tbe repressor, releasing it from tbe gene and allowing tbe RNA polymerase to bind.

Gene

is

ON

RNA