Question

What are the components of lac operon?

Answer 1

Lac operon:

1. $\beta$ galactosidase, lac permease, and transacetylase are three genes that are responsible for lactose catabolism.
2. The DNA segments of the enzyme are represented as lac-Z, lac-Y, and lac-A.
3. They are located in a linear sequence in the bacterial chromosome.
4. These genes are controlled in a coordinated fashion by some regulatory genes which in turn along with structural genes form an operon.
5. There are three components of an operon namely- the operator gene, promoter gene, and regulatory gene.

Operator:

1. It lies just before the structural gene.
2. It controls the transcription of mRNA from structural genes.
3. It is controlled by the repressor molecule, produced by the regulator or repressor gene.

Promoter gene:

1. It is adjacent to the operator gene.
2. RNA polymerase bind to the promoter gene.
3. It controls the rate of mRNA synthesis.

Regulator gene:

1. It is located outside the operon.
2. It produces a repressor substance.
3. This repressor binds to the operator gene and suppresses the transcription of structural genes.

Figure showing lac operon: