All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit

All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit

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All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit. Such units are generally called operons (from operational units). The lac operon is only transcribed when lactose is present and the gene products are therefore needed. DNA: . ...... Jacob and Monod proposed their model of regulation solely on the basis of genetic data derived from mutants. We will only talk about the model and not about the genetic data that led them to this model. Mutants showed that there are two distinctive DNA sequences that are necessary for
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Unformatted text preview: lac operon regulation (Fig. 6.8): lac O (called operator , a non-coding DNA sequence that lies just downstream of the transcription start site) lac I (a gene somewhere else on the chromosome that encodes a repressor protein called lac repressor ) With no lactose present : The lac repressor binds to the operator and blocks transcription. When lactose is present : lactose binds to the lac repressor, the repressor cannot bind the operator anymore and transcription is initiated....
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This document was uploaded on 11/03/2011 for the course BIOLOGY MCB2010 at Broward College.

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