Question

Draw an operon of your own design – the funnier the better! Be sure to indicate if your operon is positively or negatively regulated, inducible or repressible. Indicate the co-repressor or inducer molecules. Remember that operons are only active in unicellular prokaryotes, so keep that in mind!

Answer 1

Please look in the image:

Explanation:

I have taken the Lac Operon is an example which is found in the E coli. This is the case of negative conteolled inducible operon. Because structural gene expressed in presence of inducer.

Open only the segment of DNA which includes regulatory gene, structural gene, promoter gene and operator gene.

Case 1: in the absence of lactose:

Regulatory gene and codes mRNA by the process of transcription. Then it undergo the translation process and produces repressor protein. The repressor protein is active in form it will bind to the operator. Then RNA polymerase bind to the promoter but it will not proceed further because of hinderance at the operator region. That's why there is not found expression of structural gene.

Case 2: Presence of lactose:

Lactose acts as an inducer. It will bind to the repressor protein and inactivate the repressor protein. Now repressor protein cannot bind to the operator but RNA polymerase bind to the promoter. It will proceed further to the structural genes and leads to the synthesis of mRNA by the process of transcription. Now the mRNA undergoes the translation process and produces beta galactosidase from Z gene, permease from y gene and transacetylase from a gene. Beta-galactosidase breakdown lactose into glucose and galactose. Permease allows lactose entry into E coli and transacetylase helps in the detoxification of drug.