Question

Describe how the lac operon functions, and explain how it permits E. coli to produce the enzymes needed to break down lactose when it is present in the bacterium.

Answer 1

The lac operon functions under two mechanisms. The cell has to be lacking glucose and has to be in the presence of lactose. The lac operon is a gene that codes for the enzyme lactase that allows the cell to break down lactose into glucose and galactose for the cell to metabolize for energy.

When glucose levels are high, cAMP has low levels and doesn't bind to the CAP protein allowing the protein to bind to DNA to transcribe the protein. When glucose levels are low though, more cAMP is produced binding to the CAP protein allowing the transcription of the gene.

When lactose is not present, there is a repressor protein that is bound to the gene inhibiting the transcription but when lactose is present it binds to the repressor protein releasing it from the gene allowing transcriptoin.

So for this process to occur you need to have both the presence of lactose and the absense of lactose

Answer 2

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