Question

The given figure shows lac operon model and its functioning. Select the option which correctly labels A, B, X, Y and Z marked in the figure and also identify the label (L) which is primarily responsible for the hydrolysis of the disaccharide, lactose, into galactose & glucose

• A. A= Repressor ,B=Inducer ,X= $\beta$-Galacto-sidase ,Y= Permease ,Z= Transacetylase ,L= X
• B. A= Repressor ,B=Inducer ,X= Permease $\beta$-Galacto-sidase ,Y= ,Z=Transacetylase ,L= Y
• C. A= Inducer ,B=Repressor ,X= $\beta$-Galacto- sidase ,Y= Permease ,Z=Trans-acetylase ,L=Z
• D. A=Inducer ,B=Repressor ,X= $\beta$-Galacto- sidase ,Y= Trans- acetylase ,Z=Permease ,L=B

Answer 1

Answer: (A)

In the given figure of lac operon model (proposed by Jacob and Monad), the labels A, B, X, Y and Z are respectively repressor, inducer, $\beta$ - galactosidase $(z)$, permease $(y)$, transacetylase $(a) . z, y$ and a are three structural genes which produces three enzymes for the degradation of lactose to glucose and galactose. Label X ( $\beta$ galactosidase) is primarily responsible for the hydrolysis of disaccharide lactose into galactose and glucose.