Question

What is the difference between repressor and corepressor?

Answer 1

Structural genes:

1. These genes carry codes for the synthesis of protein.
2. These determine the primary structure of a polypeptide chain by having the coding sequence of amino acids in them.

Regulatory genes:

1. These are the genes that are synthesized for controlling the functions of structural genes.
2. Important regulatory genes include promoters, terminators, operators, and repressors.

Repressor: It is the synthesizer of the main repressive gene that blocks the function of the structural gene.

Co-repressor: It is the accessory molecule that binds to the repressor to bring about the indirect suppression of the structural genes.

Repressor	Corepressor
It is a protein synthesized by the regulatory gene. It is meant for blocking the operator gene so that the structural gene is unable to form mRNA.	It is also a protein synthesized by a regulatory gene but it binds with the repressor protein so that it can indirectly block the expression of the structural gene.
It goes and binds to the operator of an operon.	It cannot directly bind with the operator DNA sequence thus, it binds to the repressor protein.
It helps in gene regulation by blocking the attachment of the promotor region with RNA polymerase.	It helps in gene regulation by binding to the repressor protein and by activating the repressor transcription factors.