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1.Briefly describe the lac operon and how it controls the metabolism of lactose. 2 .What is...

1.Briefly describe the lac operon and how it controls the metabolism of lactose. 2

.What is catabolite repression? How does it allow a bacterial cell to use glucose in preference to other sugars?

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1. The lac operon is the group of genes involved in the metabolism and transport of lactose in the bacteria. The structure of this operon include :

I. 3 structural genes that are lac Z, lac Y and lac A.

II. The promoter sequence.

III. The operator sequence

This operon is induced type of operon as these genes are transcribed only when lactose is present in the cell and bacteria need to metabolize. Normally this operon is off.

2. The catabolite repression is the mechanism of gene control in  some bacteria operon where sugar glucose is preferable used as compare to other sugars . Therefore this mechanism allow bacteria to metabolize the glucose sugar when all other sugars like lactose is present in the cell. The catabolite repression is the positive control of lac operon and increase the expression of gene involved in the transcription.

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