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

Multiple Choice

A compound known as X-gal is widely used in molecular genetic research. When wild-type (normal) E. coli is grown on medium containing X-gal, the bacterial colonies turn blue. In contrast, when lacZ mutants are grown on medium containing X-gal, the bacterial colonies remain their normal white color. X-gal is likely to be a compound ________.

A) chemically similar to glucose
B) chemically similar to galactose
C) chemically similar to lactose
D) that cannot be transported into lacZ mutants
E) that can be transported only into lacA mutants