Question

Proteins encoded by the genes _____and ____, which control the cotton bollworms.

• A. Cry I Ab and CryI Ac
• B. Cry I Ab and Cry II Ac
• C. Cry I Ac and Cry II Ab
• D. Cry II Ab and Cry II Ac

Answer 1

Answer: (C)

Cry I Ac and Cry II Ab

Answer 2

The correct answer is option (C): Cry I Ac and Cry II Ab
The cry genes encode the crystal protein (Bt toxin)that is toxic to some plant species. The cry genes are produced during the growth of Bacillus thuringiensis. The cry genes cry I Ac and cry II Ab , help in killing the cotton bollworms. The cry toxin has specific activity against the insects of the order Diptera, Coleoptera, and Lepidoptera. When the insect ingests these crystals, the alkaline medium provided by their digestive system denatures the insoluble crystal. This will be cut with proteases in the gut, which will further liberate toxins. The toxin will eventually form pores in the digestive tract and thus paralyze the insect.