Question

Explain the following term in connection with the concept of the lac operon in E.coli:

Structural genes

Answer 1

In the lac operon, structural genes are the specific DNA sequences that code for the enzymes required to metabolise lactose. There are three primary structural genes, lacZ, lacY, and lacA, which are positioned sequentially and transcribed together as a single unit. lacZ encodes the enzyme β-galactosidase, which breaks lactose down into glucose and galactose; lacY encodes permease, which increases the cell’s permeability to lactose; and lacA encodes a transacetylase enzyme. Because these genes are linked under a single regulatory system, the cell can ensure that all the necessary components for lactose processing are produced simultaneously only when the sugar is present and needed.