E. coli cells with a mutated Z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because

in the presence of glucose, E. coli cells do not utilize lactose

they cannot transport lactose from the medium into the cell

the lac operon is constitutevely active in these cells

they cannot synthesize functional $β$ - galactosidase

Solution

they cannot synthesize functional $β$ - galactosidase

Lac operon is a cluster of genes encoding three proteins that bacteria use to obtain energy from the sugar lactose. There are three structural genes in lac operon.

(i) Lac Z (3063bp)- This genes codes for enzyme $β$ - galactosidase. It breaks lactose into glucose and galactose. Therefore, E. coili cells with a mutated Z genes cannot grow in medium containing only lactose as the source of energy because they cannot synthesize functional $β$ - galactosidase.

(ii) Lac Y (800 bp)- This gene codes for enzyme $β$ galactose permease. It is a membrane bound protein and helps in the transport of metabolites.

(iii) Lac A (800bp)- This gene codes for enzyme $β$ - galactose transacetylase. It transfers an acetyl group from acetyl Co- A to $β$ - galactosidase.

Some More Questions From Molecular Basis of Inheritance Chapter

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Molecular Basis Of Inheritance

Some More Questions From Molecular Basis of Inheritance Chapter

Suggest one evidence to prove that RNA was first genetic material.

Why was RNA unstable ?

What made DNA more preferrable as genetic material ?

Process of replication is completed in how much time in E.coli ?

What is average rate of polymerization ?

List three components of transcription unit.

Which RNA acts as an adapter ?

Name three kinds of polymerases.

What is splicing ?

Which is more stable DNA or RNA?

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