A compound known as X-gal is widely used in molecular biology research. When wild-type E. coli is grown on an agar plate containing X-gal, the bacterial colonies turn blue. In contrast, when lacZ mutants are grown on an agar plate containing X-gal, the bacterial colonies remain their normal white color. What is X-gal likely to be?

Question

Quizplus · Accepted Answer

X-gal is a substrate for the enzyme β-galactosidase, which is encoded by the lacZ gene. This enzyme normally processes lactose, so X-gal is designed to mimic lactose chemically. When X-gal is cleaved by β-galactosidase, it releases a blue product, indicating the presence of functional lacZ.

A Compound Known as X-Gal Is Widely Used in Molecular