Question

Describe the 'Lac-operon'.

Answer 1

The lac operon (lactose operon) is anoperon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. ... The gene product of lacZ is β-galactosidase which cleaves lactose, a disaccharide, into glucose and galactose.


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Answer 2

Answer:

Lac operon consists of the following Components:

(1) Regulator gene :

(a) Regulator gene precedes the promoter gene.

(b) It may not be present immediately adjacent to operator gene.

(c) Regulator gene codes for a repressor protein which binds with operator gene and represses (stops) its action.

(2) Promoter gene:

(a) lt precedes the operator gene.

(b) t is present adjacent to operator gene.

(c) RNA Polymerase enzyme binds at promoter site. Promoter gene base sequence determines which strand of DNA acts a template.

(3) Operator gene :

(a) It precedes the structural genes.

(b) When operator gene is turned on by an inducer, the structural genes get transcribed to form m-RNA

(4) Structural gene

(a There are 3 structural genes in the sequence lac-z, lac-Y and lac-A.

(b) Enzymes produced are. B-galactosidase, B-galactoside permease and transacetylase respectively.

Inducer: Allolactose acts as an inducer. It inactivates the repressor by binding with it.