Textbook Question
Contrast positive versus negative control of gene expression.
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Contrast positive versus negative control of gene expression.
Contrast the role of the repressor in an inducible system and in a repressible system.
How do we know that the trp operon is a repressible control system, in contrast to the lac operon, which is an inducible control system?
How do we know that the lac repressor is a protein?
For the lac genotypes shown in the following table, predict whether the structural genes (Z) are constitutive, permanently repressed, or inducible in the presence of lactose. Genotype Constitutive Repressed Inducible I⁺O⁺Z⁺ x I⁻O⁺Z⁺ I⁻OᶜZ⁺ I⁻OᶜZ⁺/F'O⁺ I⁺OᶜZ⁺/F'O⁺ IˢO⁺Z⁺ IˢO⁺Z⁺/F'I⁺
What led researchers to conclude that a repressor molecule regulates the lac operon?