Concept explainers
(a)
To explain: The reason why an inactivation of O2 or O3 sequence of the lac operon causes only a two-fold loss in repression.
Introduction: Operon contains coding DNA sequences, regulatory DNA sequences, and the regulatory proteins. Regulatory proteins are both activators (TURN ON) and repressors (TURN OFF). Based on these, operons may be classified as inducible (usually ‘off’) and repressible (usually ‘off’). The lac operon is an inducible operon and controls the
(b)
To explain: The reason why inactivation of both O2 and O3 of the lac operon reduces the repression approximately to 70-fold.
Introduction: Operon contains coding DNA sequences, regulatory DNA sequences, and the regulatory proteins. Regulatory proteins are both activators (TURN ON) and repressors (TURN OFF). Based on these, operons may be classified as inducible (usually ‘off’) and repressible (usually ‘off’). The lac operon is an inducible operon and controls the metabolism of the lactose sugar through β-galactosidase enzyme.
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