Question

What is the function of the enzyme coded by the gene Z?

Answer 1

Lac operon:

1. The lactose operon is involved in the lactose catabolism of E. coli. Operons are composed of regulatory genes and structural genes.
2. The famous operon model was proposed by Jacob and Monod in 1961. It is used to break down the lactose of bacteria.
3. The lac operon is composed of regulatory genes (regulators, operators, promoters), and structural genes. These structural genes are regulated by promoter and regulator genes.

Structural genes:

1. These are the segments of DNA that determine the primary structure of a polypeptide that is synthesized under the control of an operator, and the operator is controlled by a regulator.
2. These three structural genes encode specific enzymes required for the breakdown of lactose.

Three types of structural genes present in the lac operon are:

1. Z gene: Synthesizes the enzyme β-galactosidase, which has the function of breaking down lactose into glucose and galactose.
2. Y gene: Synthesizes the enzyme Lac permease, which has the function of transporting lactose into cells.
3. A Gene: Synthesizes transacetylase, an enzyme that protects cells from toxins.

Thus, the structural gene "Z" synthesizes an enzyme that hydrolyzes lactose into glucose and galactose by cleaving glycosidic bonds.