Describe how bacteria are used to genetically modify crops. Describe two examples of GM crops. Describe the reasons why some are opposed to GM crops

Describe how bacteria are used to genetically modify crops.• Certain bacteria (Agrobacterium) can cause plant cells to multiply and form tumours by inserting plasmid DNA into genome of plant• Restriction enzyme used to remove tumour-forming gene, replacing it with a gene for e.g. drug resistance • Thus when recombinant bacteria infect plant, gene for drug resistance added to genome Describe two examples of GM crops • Soya: major source of food; treated to be tolerant to weed killer; sprayed onto crops but only weeds die; this breaks down in soil into harmless component• Tomatoes: ripen when enzyme breaks down pectin in cell wall; complement of gene for enzyme added to genome. Thus both enzyme and complement transcribed forming two mRNAs which form a ds-mRNA molecule, which cannot be translated - Flavr Savr; longer shelf life of tomatoes Describe the reasons why some are opposed to GM crops• Pollination - genes transferred to plants/wild counterparts with unforeseen effects• Some contain marker genes for antibiotics resistance - concerns of transfer back to bacteria of intestine of consumer• Commercialisation leads to decrease in biodiversity of crops meaning susceptibility to attack increases• Commercial growth could compromise organic farming due to cross pollination by wind and insects