Question

You are creating a transgenic Drosophila where the gene EY is regulated by a conditional promoter under control of the LacI protein. You want the gene EY to be expressed during embryonic development but then not expressed in adults. What sequences would you need to add to the Drosophila genome to regulate EY expression with the LacI protein? How would you turn EY’s expression on? How would you turn it off?You are creating a transgenic Drosophila where the gene EY is regulated by a conditional promoter under control of the LacI protein. You want the gene EY to be expressed during embryonic development but then not expressed in adults. What sequences would you need to add to the Drosophila genome to regulate EY expression with the LacI protein? How would you turn EY’s expression on? How would you turn it off?

Answer 1

Lac I protein controls the expression of EY gene in Drosophila. The operator sequences are added in the Drosophila's genome to regulate EY expression by lacI protein.

Because the operator sequences allows the binding of Lac I protein to it and regulates the expression of EY gene (structural genes in case of bacteria).

* lactose is added in the medium of Drosophila during its embryonic development. This lactose binds to the repressor protein. It inactivates the repressor protein (Lac I) . The repressor protein can not bind to the operator. RNA polymerase binds to the promoter. RNA polymerase proceeds further to the EY gene and it will express in embryonic development in Drosophila.

* Lactose is not provided to the adult Drosophila and glucose is added. In this case repressor remains in active form. It will bind to the operator. RNA polymerase can not bind to promoter. There is not found any expression of EY gene in adult.