Question

Why IPTG is used for expression studies than lactose/ allolactose in E. coli?a. Concentration remains constant

Answer 1

But unlike allolactose, the sulfur (S) atom creates a chemical bond which is non-hydrolyzable by the cell, preventing the cell from metabolizing or degrading the inducer. The concentration of IPTG therefore remains constant and the expression of lac p/o-controlled genes would not be inhibited during the experiment.