Question

Cry proteins are not toxic to humans because:

• A. The medium in human gut is acidic.
• B. The medium in human gut is basic.
• C. Cry proteins are destroyed by saliva.
• D. None of the above.

Answer 1

The correct option is A

The medium in human gut is acidic.

Cry proteins are released as protoxins. It is converted into active form of the toxin due to alkaline pH of the alimentary canal of the insect. This active toxin then goes and binds to its specific receptors on the midgut epithelial cells and create pores. In humans, the alimentary canal is acidic in nature and also, the epithelial cells lack the receptors for the cry protein. Hence, it has no effect on human or other mammals.