Lecture 3701-lecture 26
10 November 2010
Foods that have had their genomes modified so as to increase their resistance to disease, competing plants, drought or insects
- can also be used to increase components of food –increased amounts of the 6 nutrient classes
Carbohydrate
Lipid
Protein
Vitamins
Minerals
Water
Specific carbohydrates, lipids, proteins, vitamins, minerals
-can be used to improve appearance or taste of food
Eg softening enzyme in tomatoes- blocked by antisense technology
What would be the advantages of genetic engineering?
Engineer strains of organisms that have been engineered to produce substances that occur in nature in small amounts or not at all
Bacteria –production of rennin-used to curdle milk to make cheese- rennin comes from lining of calves stomachs- but this is expensive- so put rennin gene in bacteria and this produces the rennin in large scale amounts and fairly cheaply
Cotton plants and other plants that produce its own herbicide-
Limitations : include a lack of control of pests not killed by the plant herbicide
High cost of transgenic plants
Development of resistance by pests
Growth enhancing gene in salmon- market ready faster
Creation of pharmaceutical producing plants and animals
Nourishment and drugs vaccines all from plants and animals
Economical way of producing food, drugs and vaccines for isolated villages for example
Rice and beta carotene- gene for beta-carotene put in rice so that people can avoid blindness (remember that vitamin A is derived from beta carotene and that vitamin A is responsible for maintaining tissue quality- in the case of vitamin A deficiency it is the cornea( piece of clear tissue on the front of the eye that loses function due to tissue damage to the cornea brought on by the deficiency of vitamin A)
This is the focus of the debate between organic and genetically modified foods
Organic camp says that there products are safer (the all-natural argument) and that they contain more nutrients than conventional foods because organic compost fertilizes plants with more vitamins and trace minerals than those provided by synthetic chemical fertilizers
However plants do not take up vitamins from either compost or other fertilizers-rather through their roots they absorb only water and elements making vitamins in the tissues of the plants
Trace minerals do get into plants and trace minerals are richer in organic compost compared to synthetic fertilizers
As to nutrient content of organic foods versus conventional foods only trace amounts of extra nutrients and the extra amounts were not significant to human health
GMOs also do not have significant greater nutrient value than either organic or conventional foods-therefore there is no health advantage
However can supplement or add additional vitamins minerals, proteins, carbohydrates and lipids into various products by virtue of genetic modification- leads to elimination of human error_how
Pesticides also occur in organic foods- drifted over from fields sprayed with pesticides
-pesticide residue limits are set well below threat to human health so organic people do not really have an argument about the risk of pesticides
-washing of foods dramatically lowers the risk of pesticides
-plant pesticides are denatured in the human body and therefore bioengineering is alright-but what about allergy or intolerance?
Unforeseen events- are the central issue with GMOs- this is why the Europeans refer to them as Frankenstein foods or Frankenfoods
Creation of unique proteins never encountered by human body
Ethical and moral issues-playing God
Imperfect technology- If a disease producing organism is used to donate genetic material to a rDNA food then it must be shown that this is not a problem-ie no dangerous characteristic comes from the disease producing organism has also entered the food
Environmental concerns
Genetic pollution
outcrossing to non GMO plants
But this can be overcome by terminator technology where offspring of outcrossed plants automatically die- such terminator technology prevents GMO genome from getting in to weeds and also does not allow farmers to save fertile seeds from their own harvests from year to year- thus poor substistence farmers would be hardest hit by all this
One alternative possibility would be to genetically modify only genes of structures (eg chloroplasts whose genetic material passes through female liness- remember only male genes are carried in the pollen
Possibly other animals may be affected by dining on transgenic plants
Crop vulnerability-outcrossing
Loss of gene pool-variabilty is reduced
Profit motive-companies are just in this for the money
Unproven safety- DNA- fear of incorporation into our genome
Increased allergens-new proteins being formed
Decreased nutrients-long storage will decrease nutrients
No product tracking- who knows where things come from-no labeling and identification to source
Over use of herbicides-to combat herbicide resistance of GMOs
Increased consumption of pesticides- cannot wash-off pesticides
Lack of oversight-no one is regulating the industry and concerned about the consumer
Risks of organic foods
E-coli
unpasteurised organic juices milk or cheeses
tend to spoil faster- no preservatives
Benefits of GMOs
Safety-GMOs are only modified in a minor way
Boost economy
Ethical and moral issues-benefits of feeding more people- Bumper crops on far fewer acres with less erosion and use of water and use of pesticides and herbicides
Genetic engineering could save rainforest-less acreage needed to supply a living to farmers
Genetic improvements are more likely to benefit than harm
Improved crop resistance-disease, drought, plant competitors, and insects
Gene pool preserved- in laboratories
Control of allergens-most allergens are known and no new ones are being created in GMOs
Increased nutrients – eg beta carotene in rice
Excellent product tracking-easy to regulate
Conservative use of herbicides-not trying to overcome GMO herbicide capability
Reduced use of pesticides-pesticide resistance built in
Sufficient regulation and rapid response-good tracking and regulations laid down-