Question

Why the whole lacZ gene can’t be present in the plasmid at one time?

(a) Because the whole lacZ gene can’t be present anywhere

(b) The whole lac Z gene is very large in size and the plasmid size is small

(c) The whole lacZ gene is never functional

(d) Because the plasmid takes is having a restriction site only for taking up a portion of the lacZ gene

The question was posed to me at a job interview.

My doubt stems from Cloning using a Simple Plasmid and Alpha Complementation topic in chapter Simple Cloning of Genetic Engineering

Answer 1

Correct answer is (b) The whole lac Z gene is very large in size and the plasmid size is small

The explanation: The whole lacZ gene is not present in a plasmid because the plasmids are generally small in size and the lacZ gene is large in size. And if the whole gene is present, it makes the overall size very large.