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The map of the lac operon is POZY. The promoter (P) region is the start site of

ID: 19826 • Letter: T

Question

The map of the lac operon is POZY. The promoter (P) region is the start site of transcription through the binding of the DNA polymerase molecule before actual mRNA production. Mutationally altered promoters (P -) apparently cannot bind the RNA polymerase molecule. Certain predictions can be made about the effect of P - mutations. Use your predictions and your knowledge of the lactose system to complete the following table. Insert a “+” where and enzyme is produced and a “-” where no enzyme is produced. The first one has been done as an example.

ß-Galactosidase Permease
Genotype No lactose Lactose No lactose Lactose

a. I- P+ OC Z+ Y- / I+ P+ O+ Z- Y+

b. I+ P- OC Z- Y+ / I- P+ OC Z+ Y-

e. I- P+ OC Z+ Y- / I- P+ O+ Z- Y+

f. I- P- O+ Z+ Y+ / I- P+ OC Z+ Y-

Could you guys explain one of them? (a, b, e, f)



Explanation / Answer

a) I- P+ OC Z+ Y- / I+ P+ O+ Z- Y+ ans) b-Glactosidase : No lactose(+) ,Lactose (+) Premease : No lactose(-) ,Lactose (+) b) I+ P- OC Z- Y+ / I- P+ OC Z+ Y- ans) b-Glactosidase : No lactose(+) ,Lactose (+) Premease : No lactose(-) ,Lactose (-) e) I- P+ OC Z+ Y- / I- P+ O+ Z- Y+ ans) b-Glactosidase : No lactose(+) ,Lactose (+) Premease : No lactose(+) ,Lactose (+) f) I- P- O+ Z+ Y+ / I- P+ OC Z+ Y- ans) b-Glactosidase : No lactose(+) ,Lactose (+) Premease : No lactose(-) ,Lactose (-)