Biotechnology and its Applications — BIOLOGY STD 12 Science — Question
Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYBiotechnology and its Applications3 Marks
Question
How has the study of biotechnology helped in developing pest-resistant cotton crop? Explain.
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Answer
Cotton plants resistant to insect pests like lepidopterans have been raised through recombinant DNA technology using the genes from the bacterium, Bacillus thuringiensis, which produces Bt-toxins. The genes crylac and cryllAb, encoding the Bt toxins, have been isolated from the bacterium and incorporated into cotton plants.
The genes code for the insecticidal crystal protein, that is ingested by the insect pest along with the plant parts.
The inactive toxin is converted into its active form by the alkaline pH of the gut.
The active form of the toxin binds to the surface of the midgut epithelial cells and creates pores that cause swelling and lysis of the cell and eventually kills the insect pest (lepidopterans).
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