The proteins encoded by all the structural genes of the $lac$ operon are essential for which process?

What happens if an $ATT$ sequence appears in the middle of the template strand of the $Lac\, y$ gene?

Select the two correct statements out of the four $(i-iv)$ statements given below about the lac operon.
$(i)$ Glucose or galactose may bind with the repressor and inactivate it.
$(ii)$ In the absence of lactose,the repressor binds with the operator region.
$(iii)$ The $z$-gene codes for permease.
$(iv)$ This was elucidated by Francois Jacob and Jacques Monod.
The correct statements are:

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

Which of the following enzymes increases the permeability of the bacterial cell to lactose?

An $E. coli$ cell with a mutated $z$ gene of the $lac$ operon cannot grow in a medium containing only lactose as the source of energy because: