Index >> Bacteriophages - Part Two >> Lysogeny and Lytic Development

Lysogeny and Lytic Development -
The early stages of both lytic and lysogenic cycles require the products of the delayed early genes. It is only subsequently that the two pathways diverge, leading to either lysogenic or lytic development.

This is brought about by an interplay of regulator proteins. The lambda repressor, a product of the cI gene, blocks the action of the left promoter and the right promoter.

The gene cro of the immunity region codes a protein which can block the production of the repressor protein.

Thus whether development with follow the lytic or the lysogenic cycle depends, on whether the cro gene product is synthesized to a greather ex tent than the repressor protein.