Mendel drew from his monohybrid cross was that the two alleles  in each plant separate when gamete are formed, and one allele goes into each gamete.

The two alleles of an individual plant separate with equal probability into the gametes.

Independent assortment

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#Unit 2. Cellular Organization

When polymerase binding causes transition to the open complex and initiates transcription. This gives a low level of constitutive expression called the basal level.  Binding of RNA polymerase is the rate-limiting step in this case.

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#Unit 2. Cellular Organization

Lac repressor binds as a tetramer to two operators.

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#Unit 2. Cellular Organization

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#Unit 2. Cellular Organization

lacZ encodes for b-galactosidase,a tetramer of 500 kD. The enzyme breaks lactose is cleaved into glucose and galactose.  This enzyme also produces an important byproduct, b-1,6-allolactase.

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#Unit 2. Cellular Organization

The lac mRNA (as most mRNA is in bacteria) is extremely unstable and decays with a half-life of only 3 minutes.

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#Unit 2. Cellular Organization

B-1,6-allolactase is a true inducer of Lac operon which activates Lac ZYA gene expression by inhibiting Lac Repressor