In $lac$ operon,the gene '$i$' codes for repressor protein,the letter '$i$' indicates . . . . . . .

Describe the regulation of gene expression in prokaryotes with an example.

Lac operon is:

In eukaryotes,the regulation of gene expression could be exerted at $:-$
$(I)$ Transcriptional level (formation of primary transcript)
$(II)$ Processing level (regulation of splicing)
$(III)$ Transport of $\text{mRNA}$ from nucleus to the cytoplasm
$(IV)$ Translational level
Choose the correct order for given statements $:-$

Which of the following switches off the $lac$ operon?

The one gene-one enzyme hypothesis was postulated by