Which is likely to occur in E. coli cells that are grown in milk (Hint: Milk...

Which is likely to occur in E. coli cells that are grown in milk (Hint: Milk contains lactose sugar)?

The lac operon is shut off, and the cells will not produce lactose-utilizing enzymes.

The lac repressor is inactivated, and the cells will produce lactose-utilizing enzymes

The lac operon is turned on, but the bacteria will not produce lactose-utilizing enzymes. ---- wrong

Solutions

Expert Solution

Answer: The lac repressor is inactivated, and the cells will produce lactose-utilizing enzymes

Explanation: Lac operon is an inducible operon that is only activated when the medium contains lactose. Lac operon consists of a regulatory gene, operator, promotor, and three structural genes. The regulatory gene encodes for active repressor proteins. The repressor protein binds to the operator gene so that RNA polymerase could not bind to the promoter resulting in the turning off of the operon. Let's consider two cases:

The case I: When the lactose is present in the medium.

Lactose will bind to the repressor resulting in the inactivation of repressor molecules. So repressor molecules could not bind to the operator and RNA polymerase initiates transcription of structural genes. The structural genes encoding for the enzymes for the metabolism of lactose.

The case II: When lactose is absent in the medium:

When lactose is absent in the medium, the repressor protein binds to the operator gene so that RNA polymerase could not bind to the promoter resulting in the turning off of the operon.

gladiator answered 1 year ago

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