Biotechnology and Its Applications Question 17
17. Bacillus thuringiensis forms protein crystals which contain insecticidal protein that [2011M]
(a) binds with epithelial cells of midgut of the insect pest ultimately killing it
(b) is coded by several genes including the gene cry
(c) is activated by acid $pH$ of the foregut of the insect pest.
(d) does not kill the carrier bacterium which is itself resistant to this toxin
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Answer : a
Hints & Solutions
(a) Bacillus thuringiensis produces a large amount of crystalline protein during sporulation. In the cell, toxins are formed along with the spore and are referred to as parasporal body. The bacteria are capable of entering the insect’s blood and using the host insect to reproduce. The proteins from ingested spores are activated by gut high $pH$ and the polypeptide toxins destroy gut epithelial cells and kill the pest.
