BHU PMT BHU PMT (Screening) Solved Paper-2010

  • question_answer
    \[\text{Cry-I}\] endotoxins obtained from Bacillus thuringiensis are effective against

    A)  mosquitoes                      

    B)  flies

    C)  nematodes      

    D)  boll worms

    Correct Answer: B

    Solution :

                     Insect resistant transgenic plants contain either a gene from the bacterium Bacillus thuringiensis or some other gene. The Cry gene of Bacillus thuringiensis produces a protein, which forms cry stalline inclusion in the bacterial spores. These crystal proteins are responsible for the insecticidal activities of the bacterial strains. Cry-\[\text{I}\]   endotoxins   are   effective   against Lepidoptera (eg, flies). Cry\[\text{-V}\] and Cry\[\text{-VI}\] proteins are effective against nematodes. Cry\[\text{-IV}\]proteins   are   effective   against   Diptera (mosquitoes). When Cry proteins are ingested by insects, they are dissolved in the alkaline juices present in the midgut lumen. The gut proteases process them hydrolytically to release the core toxic fragments. The toxic fragments are believed to bind to specific high affinity receptors presents in the brush border of midgut epithelial cells and causing their swelling and eventual lysis.


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