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Some questions of this chapter are given here.
Q. Compare and contrast the advantages and disadvantages of production of genetically modified crops.
Answer. The production of genetically modified (GM) or transgenic plants has several advantages.
(i) The post harvesting loss of crops can be decreases by the use of GM crops. However, there are certain controversies regarding the use of genetically modified crops around the world, In an area, the native biodiversity can affected by the use of GM crops .For example, the use of Bt toxin to decrease the amount of pesticide is posing a threat for a beneficial insect pollinators such as honey bee. If the gene expressed for Bt toxin gets expressed in the pollen, then the honey bee might be affected. As a result, the process of pollination by honey bees would be affected.
(ii) GM crops are mostly developed for pest resistance, which increases the crop productivity and therefore, reduces the dependency on chemical pesticides.
(iii) GM crops are developed to increase the nutritional quality. For example, golden rice is a transgenic variety in rice, which is rich in vitamin A
(iv) GM plants are also accountable to prevent the loss or fertility of soil by increasing the efficiency of mineral usage.
(v) They are highly tolerant to unfavorable abiotic conditions.
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Q. What are Cry proteins? Name the organism that produces it. How has man exploited this?
Answer. Cry genes are mainly responsible to encode the Cry proteins. These proteins are toxins, which are produced by Bacillus thuringiensis bacteria. This bacterium contains these proteins in their inactive from when the inactive toxin protein is ingested by the insect. Alkaline pH of the gut makes them active. This results in the lysis of epithelial cell and eventually the death of the insect Therefore, man has exploited this protein to develop certain transgenic crops with insect resistance such as of cotton, Bt corn, etc.
Q. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Answer. Correction of defective gene through gene manipulation by using the technology is known as gene therapy. It involves the delivery of a normal gene into the individual to replace the defective gene, for example, the introduction of gene for adenosine deaminase (ADA) in ADA deficient individual. The adenosine deaminase enzyme is accountable for the normal functioning of the immune system. This disorder can be cured by transplantation of bone marrow cells. The first step involves the extraction of lymphocyte from the patient’s bone marrow. Then, a functional gene for ADA is introduced into lymphocytes with the help of retrovirus. These treated lymphocytes containing ADA gene are then introduced into the patient's bone marrow. Once the gene gets activated, it will produce functional T- lymphocytes and activating the patient's immune system.