Question

Explain the components of the structural genes in the Lac operon system in E.coli.

Answer 1

The Components of the structural gene of Lac operon:

1. The three genes responsible for lactose catabolism are B-galactosidase, lac permease, and transacetylase.
2. The enzyme's DNA segments are represented as lac-Z, lac-Y, and lac-A.
3. They are found in a linear sequence in the bacterial chromosome.
4. Regulating genes coordinate with structural genes to form an operon.
5. An operon consists of three components: the operator gene, promoter gene, and regulatory gene.
   • Operator gene -
     1. It appears right before the structural gene.
     2. It regulates mRNA transcription in structural genes.
     3. The regulator or repressor gene produces the repressor molecule, which controls it.

   • Promoter gene -

     1. It's adjacent to the operator gene.
     2. RNA polymerase associates with the promoter gene.
     3. It regulates the rate of mRNA production.
   • Regulator gene -
     1. It is found outside the operon.
     2. It generates a repressor substance.