List any six features of genetic code.

Explanation

Structural genes: .Z. for `beta` - gataclosidase, `gamma` for galactoside permease, .A. for galactosidetransacetylase.
Regulatory gene - Regulator, promoter and operator Operon - off (switch off) - in the absence of lactose in the medium regulator directs the synthesis of repressor protein that finds to operator.
Operator gets repressed. RNA polymerase cannot bind to the promoter since a part of operator overlaps promoter. Structural genes are switched-off and therefore neither mRNA nor the enzymes are synthesized.
Operor - On (switch on) - In the presence of lactose in the medium represent binds to lactose forming lactose-repressor complex.. Operator is derepresented RNA polymerase interacts with the exposed promoter. Structural genes are switched on and therefore a polycistronic mRNA is synthesized followed by the synthesis of the enzymes.