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1. The lac operon responds to lactose and glucose. If wild-type E. coli cells ar

ID: 195100 • Letter: 1

Question

1. The lac operon responds to lactose and glucose. If wild-type E. coli cells are grown in media that contains both lactose and glucose, they will consume the glucose first because: (select all that apply)

2.) The small molecule that regulates CAP's ability to bind DNA: (select all that apply)

3.) The lac operon is regulated by BOTH a repressor AND an activator because: (select all that apply)

4.) The following mutation(s) would cause the lac operon to be expressed at less than maximal levels in the presence of lactose & absence of glucose: (select all that apply)

A.) the lac repressor remains bound to lacO, preventing the lac operon from being expressed at maximal levels

Explanation / Answer

Repressor is bound at lac o and prevent lac operon to express.

Cap protein is unable to bind at caps site due to lower level of cmp hence option A and C are correct

2. CAP is present in lower level binded with cAMP in higher concentration of glucose hence option C is right.

3. Operon always need a repressor or activate a protein to express operon and they are never complete not on or off hence option D is right.

4. Mutation which remain always CAP binded at cap site will result in highr expresson of operon so option B is correct.