Transcript document
GENETICALLY MODIFIED FOODS Genetically from the word ‘Gene’. Genes control the characteristics that are passed from one generation to the next. Genes are copied every time a cell reproduces and is made up from Deoxyribonucleic Acids (DNA). GM food is copying a gene with its code for a particular characteristic and inserting it into another living organism. This will then be reproduced in the new organism. Genetic engineers use enzymes to do this. Often done to improve crop yield, offspring, resistance to disease, increased storage, resistance to chemicals. Most come crops are oilseed rape, soya beans, cotton, kiwi fruit, maize, sugar beet, potato and tomatoes. Working on bacteria, fungi, animals and fish to grow faster, less fat, disease resistance. What are GM foods? All living things are made up of genetic material. Nature has always changed the genetic properties of living things by mutation and natural selection. Now modern scientists can change the genetic make up of cells to change their properties. For example, genetic engineering could allow certain characteristics of wild wheat to be transferred to wheat grown as a crop to make it more resistant to disease. How are foods genetically modified? Scientists use chemical ‘scissors’ to obtain the DNA or gene they want to transfer. It could come from an animal, a plant or bacteria. They then place it into a plant cell. The DNA then gets into the nucleus of the plant, and new cells grow from the altered ones to make plants with the new characteristics. The DNA will have been chosen to pass on the feature they want the new plant to have. Gene taken from bacterium that produces a natural insecticide Added to wheat cells Wheat that does not need to be sprayed against insects Why are foods genetically modified? Some genetic engineering is done for economic reasons – the crop will grow bigger or faster and so make more money. GM crops may be useful to poorer countries if they need less water, or are more resistant to pests and diseases. Some genetic research is for medical developments such as new vaccines or cancer treatments. It may be possible to make biodegradable plastics from plants to reduce the amount of fossil fuel we use and help the environment. Tomatoes, modified to contain three times the normal amount of vitamin A, may help prevent cancer, scientists claim. Genetically modified enzymes Enzymes are proteins that speed up chemical reactions such as digesting food. Chymosin is an enzyme extracted from the stomach of calves which is added to milk as rennet to make cheese. An equivalent enzyme can be made from genetically modified micro-organisms such as yeast. This means the cheese that is produced is suitable for vegetarians and as a result fewer calves are slaughtered. Concerns about GM • Pollen from GM crops mix with wild plants to affect the ecology. • New resistant microorganisms could develop which could cause problems in plants and animals. • People become allergic to GM foods if allergens from other plants inserted. • Often GM crops are not fertile, so seeds from current crop can’t be kept for following year. You can only tell if it is a GM crop if it is stated on the label.