Please answer all parta of this question with full details. Thanks 5. In the res
ID: 81894 • Letter: P
Question
Please answer all parta of this question with full details. Thanks 5. In the research lab, you are growing E coli bacteria which encode the lac operon. You can either grow the bacteria in a solution of glucose, lactose, or a combination of glucose and lactose. a. When the E coli are grown in the glucose solution, do you expect the lac genes to be expressed or not? Explain in your answer how the repressor protein and operator are working to control lac gene expression (you may use picture if you wish). b. When the E coli are grown in the lactose solution, do you expect the lac genes to be expressed or not? Explain in your answer how the repressor protein and operator are working to control lac gene expression (you may picture if you wish). c. When the E coli are grown in the solution containing glucose and lactose, do you expect the lac genes to be expressed or not? Explain in your answer how the repressor protein and operator are working to control lac gene expression (you may use a picture if you wish)
Explanation / Answer
a. No, lac genes are not expressed in glucose solution.
b. In lactose solution, lac genes are expressed. The lac operon contains 3 structural gene genes controlled by lac repressor. One gene codes for beta- galactosidase, a second gene codes for beta- galactosidase permease responsible for lactose uptake. 3rd codes for the enzyme beta-galactoside transacetylase.
c. In lactose and glucose solution, the lac operon will continue to be expressed as long as lactose are present. Transcription of gene are maximum when lactose is present. The lac repressor is responsible for inhibiting transcription when there is no lactose. Lac repressor is a tetramerous composed of two dimer. Each dimer binds to one of three different lac operator sites, O1,O2 and O3. O1 is the main operator site and must be bound by repressor if transcription is to be inhibited. The promoter to which RNA polymerase bind is located near the operator sites The repressor binding to operator 1 prevent imitation of transcription so that he expression is halted.
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