Question

Absence of B-galactosidase activity in recombinant pUC8 is

a)Observed in blue colonies with intact AmpR gene

b)Observed in blue colonies with disrupted AmpR gene

c)Observed in white colonies with intact AmpR gene

d)Observed in white colonies with inactivated Amp gene
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Answer 1

Answer:-β-galactosidase is important for organisms as it is a key provider in the production of energy and a source of carbons through the break down of lactose to galactose and glucose. It is also important for the lactose intolerant community as it is responsible for making lactose-free milk and other dairy products.

Explanation: so the option is a-a)Observed in blue colonies with intact AmpR gene

Answer 2

The correct answer is observed in white colonies with intact AmpR gene, so the correct option is (c).

• β- galactosidase is the source of energy as it is the enzyme that hydrolyses the lactose into galactose and glucose. Glucose acts as energy.
• It also catalyzes the isomerization of lactose into allolactose, which binds with lac repressor and causes a change in shape so that it does not bind to DNA.
•  Its absence causes the decrease in copy number of pUC8 plasmid which does not cause the expression of beta-galactosidase activity in a host and causes the expression in white colonies with intact AmpR gene.