Question
Given below are two statements:
Statement I: Bt toxins are insect group specific and coded by a gene cry IAc.
Statement II: Bt toxin exists as inactive protoxin in B. thuringiensis. However, after ingestion by the insect the inactive protoxin gets converted into active form due to acidic pH of the insect gut.
In the light of the above statements, choose the correct answer from the options given below:
Options
Solution
Sol. [Key Concept: Bt toxin specificity and activation]
Statement I is accepted in the intended sense that cry1Ac encodes an insect group specific Bt toxin; other cry genes encode other toxins. Statement II is false because ingested protoxin is activated in the alkaline insect midgut, with proteolytic processing, rather than by acidic pH. Hence, option (1).
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