GM food Product of biotechnology Wan Hing Lung(26)

What are GM foods? The food produced by genetically modified organisms,which were produced by the transfer of genes from one organism to another,was called GM food(Genetically Modified food).

Examples of GM food.

Chymosin During the production of cheese,an enzyme from the rennet is needed.However,it is expensive to obtain such enzyme and the quantity was too low. However, Microorganisms have been modified genetically to yield chymosin that is identical to the enzyme obtained from animals. Today about 90% of the hard cheese in the UK is made using chymosin from genetically- modified microbes.

How to make GM food? (example:pest resistant GM plant) a)A bacterium produces a toxic protein which kills caterpillars and other pest larvae.

b)The gene coded for the toxin was isolated

c)The gene for the toxin is introduced into a bacterial vector which is ring of DNA which has been cut open by enzymes.

d)The vector is put into another bacterium. e)The bacterium divides repeatedly,producin g many bacteria.Gene in vector is replicated.

f)The bacteria are incubated with plant cells and the vector will be transferred from the bacterial cells to the plant cells.

g)The plant cells develop to a plantlet. h)The plantlet develops to a plant that carries the gene for making the toxin.

What are the potential benefits of GM food? Increase crop yields Increase the tolerance of crops to adverse growing conditions, e.g. drought Improve the nutrient composition of crops, e.g. increase the protein content of rice Provide resistance to crop pests and reduce the use of pesticides Improve sensory attributes of food, e.g. flavor, texture Improve processing characteristics so as to reduce wastage and costs Eliminate allergy-causing properties in some foods

a.Providing resistance to pests GM corn can produce a toxin against insects,thus reducing the need for application of chemical pesticides.

b.Increasing tolerance to poor environmental conditions Antifreeze genes are inserted to potatoes with the result that the potatoes with the result that the potatoes can tolerate cold temperatures.

c.Improving nutritional content of crops People in third world countries rely on a single crop for their diet.GM rice contains additional vitamins and minerals.This solves the problem of malnutrition.

d.Reducing wastage and costs GM tomatoes have a longer shelf-life

e.Increasing crop yields Larger tomatoes can be produced.

f.Eliminating allergy-causing properties in some foods A protein in peanuts causes allergy.GM peanut has the protein removed.

Are GM food safe? World Health Organization (WHO) has pointed out that GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved.

Criticisms against GM food Development of super germs disturbing the balance of ecosystems Domination of world market for food products by a few large countries Ethical problems

a.Development of super germs GM food result in transfer of some antibiotic-resistant genes to germs. As a result,the germs became stronger and more difficult to kill.

b.Disturbing the balance of ecosystem If GM organisms are leased to the ecosystem,what will happen?

c.Domination of world market for food products by a few large countries Most GM food are produced by industrialized countries.Thus the income of farmers in developing countries may be greatly reduced. What will happen if GM organisms were released to the ecosystem? Will the food chain be changed by the GM organisms?

d.Ethical problems Is it logical to produce GM organisms? Do we have the right to change the genotype of other organisms?

Will these be produced?

Discussion Today,many environmental groups oppose the production of GM foods.Their major concern is the possible environmental impacts caused by GM food.Do you think that GM foods should be banned?

Reference Scope GM food National Centre for Biotechnology education National Centre for Biotechnology education Genetically Modified Food Howstuffworks” What are genetically modified (GM) foods?” Howstuffworks” What are genetically modified (GM) foods?” 基因改造食物教材套參考手冊 改造基因生物

END