Question

Distinguish between structural gene, regulatory gene and operator gene.

Answer 1

• Structural genes are the segments of DNA, which carry codes for the synthesis of proteins. These genes determine the primary structure of a polypeptide chain by having the coding sequence of amino acids in them. For eg, the lac operon of E.coli contains three structural genes, i.e, z, y and a.

• Regulatory genes are responsible for the synthesis of a protein called repressor. The repressor may be active or inactive (aporepressor).

• Operator gene is the segment of DNA, which exercises control over transcription. The repressor substance of regulator gene has an affinity for operator gene.