Answers

Sheetal Parihar
Jul 30, 2020

The source is Bacillus thuringiensis.
Types of crygenes cry IAc, cry IIAb, cry lAb.
Changes caused by cry genes in GM crops:
(i) The cry genes code for certain crystal proteins that have Bt toxin.
(ii) Bt toxin exists as inactive protoxin and gets converted into active form (toxin) in the alkaline pH of the gut of the insect.
(iii) The activated toxin binds to the epithelial cells lining the surface of the midgut and creates pores leading to swelling and lysis of the cells and ultimately cause  death of the insect.
(iv) This way GM crops show resistance against insect pests.