Question

Which variation of a nucleotide is involved in the lac operon and is a sign of low ATP?

A	ADP
B	PYRROPHOSPHATE
C	AMP
D	cAMP

Answer 1

Option D

Lac Operon is a type of inducible Operon. It is normally in a switched off condition whenever glucose is high in the medium and lactose is low or both glucose and lactose are high in the medium. But whenever glucose is low and lactose is high, the the Operon is switched on due to the degradation of repressor by the lactose.

Whenever the concentration of glucose in the external medium is high, the concentration of cyclic AMP is low in the cell. Under this condition, repressor is bound to operator and prevent RNA polymerase from transcribing the Operon.

But whenever the concentration of glucose in the external medium is low and lactose is high, the concentration of cyclic AMP increases inside the cell. This leads to the formation of CAP cAMP complex which then binds to the CAP site of the lac operon. This helps in the recruitment of RNA polymerase to the promoter.

In the presence of lactose in the external medium, the laptop molecules act as inducer molecules and bind to the repressor present at the operator. This leads to the degradation of repressor thereby allowing RNA polymerase to transcribe the Operon.

switched off CAP Site PROMOTER | OPERATOR llaczly A | TRNAR. REPRESSORI switched on CAP site PROMOTER OPERATOR lack/yIAT RNA P. → TRERRESSOR Olactose lac operon in prokaryotes

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