The Colorless Molecule O-Nitrophenyl Galactoside (ONPG) Can Be Used as an Artificial

Multiple Choice

The colorless molecule o-nitrophenyl galactoside (ONPG) can be used as an artificial substrate to assay b-galactosidase in cell extracts of Escherichia coli in which lacZ is used as a reporter gene. Which of the following statements is NOT true with respect to the use of ONPG?

A) Hydrolysis of ONPG by b-galactosidase produces yellow o-nitrophenol.
B) o-nitrophenol can be measured with a spectrophotometer.
C) Hydrolysis of ONPG by b-galactosidase also releases colorless galactose.
D) The o-nitrophenol moiety is blue and more suitable for use in solid media.
E) The o-nitrophenol moiety is green and less suitable for use in solid media.