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Food Chemistry Chapter 17 in Green / Damjii Chapter X in Nuess Chapter X in Oxford Study (no resource in Chang)
Homework Read F5– GM Foods- pp. 486 Do Qs 34-37 on p 493 F.5: Genetically Modified Food
Genetically modified food is a food that is produced by modifying the DNA sequence of micro-organisms, plants and animals. Genetic engineering in plant foods may involve… – Put a gene in to change behavior of cell – Inactivate a gene to remove undesired behavior – Modify a gene to get higher yields of products F.5.1: Define a genetically modified (GM) food.
Genetic engineering may be used – Directly – develop a transgenic plant / animal Plants resistant to herbicides, contain more vitamins, can grow in poor soils or harsh conditions – Indirectly – produce enzymes for food processing using genetically modified micro-organisms GM bacteria make enzyme (protease chymosin) to help convert milk into cheese – reducing the need for rennet from the stomachs of calves. Ascorbic acid, aspartame, caffeine-free coffee F.5.1: Define a genetically modified (GM) food.
ADVANTAGES (1)Pest, herbicide, and disease resistance Reduce need to use herbicides, pesticide, vaccines… all of which add to production costs, may impact our environment, and may leave their own toxic residues in food. – Ex: Crop is made to be more resistant to a particular herbicide so that less of the herbicide needs to be used to get rid of weeds – Ex: Bananas have gene that resists attack by nematods – Ex: Potatoes have gene added to resist fungal disease F.5.2: Discuss the benefits and concerns of using GM foods.
ADVANTAGES (2)Improved qualities and range Enable a food to be grown in a wider range of climatic conditions (drought, high salt content in soil &/or groundwater)... produce greater yields… mature in a shorter time. – Ex: tobacco and potato plants get a gene that makes them more cold tolerant – Ex; higher yielding rice varieties &/or rice that contains additional vitamins and minerals to prevent nutrient deficiencies – Ex: maize that can grow in areas with lower rainfall – Ex: FlavrSavr tomato – PG gene is inhibited allowing tomato to stay firm longer… to allow for harvesting, storage, and distribution… tomato is still able to ripen… just not loose its firmness. F.5.2: Discuss the benefits and concerns of using GM foods.
DISADVANTAGES (1)Possible impact on health Subtle differences in composition may cause allergic reactions in people Unknown impact on our digestive system ??? (2)Possible damage to natural ecosystems Currently gm plants are limited to particular farms… but there is a risk that pollen from them will escape into the wild population with unforeseen consequences. F.5.2: Discuss the benefits and concerns of using GM foods.