Question

Β-galactosidase activity can be detected using the lactose analog β- ____ because β-glalactosidase cleaves it to a product with a yellow color.

a) Lactate
b) Lactone
c) Lactam
d) ONPG

Answer 1

The lactose analog used to detect β-galactosidase activity is β-ONPG. When cleaved by β-galactosidase, it produces a yellow color, indicating the presence of the enzyme.

Step-by-step explanation:

β-galactosidase activity can be detected using the lactose analog β-ONPG (o-nitrophenyl-β-D-galactopyranoside) because β-galactosidase cleaves it to produce a product with a yellow color, namely o-nitrophenol. This substrate is commonly used in laboratory assays because the colorimetric change is easy to observe, indicating the presence and activity level of β-galactosidase.

The lacZ gene encodes β-galactosidase, an enzyme crucial for lactose digestion in organisms like E. coli. It cleaves lactose, a disaccharide made of β-D-galactopyranose and α-D-glucopyranose bound by a β-1→4 glycosidic linkage. When lactose analogs like β-ONPG are cleaved by β-galactosidase, researchers can observe enzyme activity through a visible color change.