Question

Assertion : 'Cry' proteins are named so because they are crystal proteins.
Reason : 'Cry' proteins are solubilised in acidic environment of insect midgut and then release toxic core fragments after proteolytic action.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

The cry gene of Bacillus thuringiensis produces a protein, which forms crystalline inclusions (i.e., is crystal in nature) in the bacterial spores. These proteins are named 'cry' proteins due to their crystal nature and are responsible for the insecticidal activities of the bacterial strains. 'Cry' proteins are solubilised in alkaline environment of insect midgut. Then these proteins undergo proteolytic digestion to release core toxic fragments. These toxins bind to receptors in brush border of midgut epithelial cells. As a result, brush border membrane develops pores, most likely non-specific in nature and cause influx of ions and water into the cells resulting in their swelling and eventually lysis.