Q) Using suitable examples, explain how genetic engineerng may result in crops that give rise to better nutritional quality and yield
Main points | |
Key idea: | Benefit of golden rice (source of vitamin A) |
· Golden rice (GM crop) - prevent vitamin A deficiency in people who consume rice as a staple food | |
Key idea: | Synthesis of golden rice |
· Rice kernel/endosperm - genetically modified to express enz in metabolic pathway · that convert geranyl geranyl diphosphate (GGPP) to β-carotene (precursor of vitamin A) · Plasmid vector fr Agrobacterium tumeficiens - introduce enz-coding genes into plant · Ref to: carry phytoene synthase (fr plant daffodil) and phytoene desaturase genes (fr soil bacterium Erwinia uredovora) into rice kernel | |
Key idea: | Benefit of Bt corn (increase crop yield via reducing spoilage by pest) |
· Corn modified to resist insect pest infestation · Adv - avoids heavy use of chemical insecticides; ref to high cost of chemical controls or remote places w limited control methods | |
Key idea: | Synthesis of Bt corn |
· Bt toxin gene fr soil bacterium Bacillus thuringiensis coding for crystal-like protein (Cry protein) transferred to genome of crop · Gene - expressed to produce inactive toxin w/n plant | |
Key idea: | Mechanism of action of Bt gene |
· Toxin - lethal to pest (e.g. European Corn Borer) but not to humans · · Cry proteins bind to specific receptors on intestinal lining, rupture cells · Gut wall breaks down, normal gut bacteria invade body cavity + multiply · Sepsis + and death of the insects w/n 2 or 3 days | |
Comments: (i) Visualize the answer through use of labelled diagram / photo (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) Underline whenever you write the scientific names (binomial nomenclature) of organism (v) Animal example is the GM salmon (increase yield) | |
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