Question

For this assignment you will complete an illustration(s) (by hand) of how the lac operon works. You should be sure to include details in your drawing such as the names of relevant structural genes (lac Z and lac Y) and controlling sequences (operator, promoter, repressor). 1. Show the influence of lactose (in the form of allolactose) on the repressor protein. 2. Show what effect the primary structural genes have on lactose. 3. Show how glucose levels can influence the expression of the lac operon (through the CRP-cAMP complex, etc...). 4. How do cAMP levels influence the expression of the lac operon and what is the mechanism? 5. Your illustrations should be detailed and make it clear how the lac operon works. Feel free to include multiple drawings and written explanations with arrows drawn to make your illustration clear. Also, creativity will be appreciated.

Answer 1

when the glucose level is low then cAMp concentration is high.

e operator lac z lacy lat A 3 5' INDUCER promote TERMA 22 blocked I Pranscript on represor active) In the presence of lactose : RNA POT lac mRNA. 3 lactose Callolactose) 1 Inactive солсоел CRP. CAMP RN pel I P 2 A y More у cupression,

Many bacteria contain a protein NAMELY CRP which is called camp receptor protein.

CRP and camp binds together and forms dimer. And it binds with the promoter sequences with a particular consensus sequence.,CRP induces a more than 90 degree bend into DNA at its binding site .

Large bends in DNA allows the CRP to contact RNA polymerase at the promoter and starts transcription from the transcription start site.

Thus camp- Cro is a positive regulator