Question

Explain the difference between negative and positive gene regulation in operons.

Similarities an differences between eukaryotes and prokaryotes gene regulation.

Answer 1

Negative versus positive control

The type of control is defined by the response of the operon when no regulatory protein is present.
In the case of negative control, the genes in the operon are expressed unless they are switched off by a repressor protein. Thus the operon will be turned on constitutively (the genes will be expressed) when the repressor in inactivated.
In the case of positive control, the genes are expressed only when an active regulator protein, e.g. an activator, is present. Thus the operon will be turned off when the positive regulatory protein is absent or inactivated.