12th Class Biology Principals And Processes Of Biotechnology

  • question_answer 21)   While isolating DNA from bacteria, which of the following enzymes is not used? (a) Lysozyme                       (b) Ribonuclease            (c) Deoxyribonuclease       (d) Protease


                      (c) In the process of 'recombinant DNA technology' the first step is isolation of DNA. Since; the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. This can be achieved by treating the bacterial ceils/plant of animal tissue with enzymes such as lysozyme (bacteria), cellutase (plant cells) and chitinase (fungus). As we know that genes are located on long molecules of DNA interwined with proteins such as histones. The RNA can be removed by treatment with ribonuclease, whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol. Deoxyribo nuclease is not used in this process as this enzyme causes the lysis of DNA molecules.

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