Question

1.How is recombinant DNA reintroduced into a bacterial cell?

2.How does cryIAc gene express itself in its host?

Answer 1

Ans1)
Host organisms such as bacterial cells are made competent by various methods. Competent host gain ability to take up the recombinant molecule of DNA ( cloning vector and gene of interest).

•Various steps involved in making cell competent are as follows:

Cells are treated with divalent cations (e.g. Ca2⁺) which increases the efficiency with which DNA enters the bacterium through pores in its cell wall.Then, these cells are incubated with recombinant DNA on ice, followed by heat shock (at 42º), and then putting them back on ice. By this, bacteria become able to take up recombinant DNA.


Ans2) CryIAc gene are naturally found in Bacillus thuringiensis (bacterium) that code for Cry proteins , which are toxins acting against pests such as cotton bollworms . Thes genes are transferred through genetic engineering in plants so these transgenic plants become resistant towards cotton bollworms. Trangenes are inserted in the host genome along with some essential elements that ensure expression of the transgene in a regulated manner. These essential elements are a promoter, (a regulatory sequence that will determine where and when the transgene is active), a segment of DNA coding for protein of interest, and a stop sequence.