Recommended Year Level: Years 9 and 10
Required Knowledge: Biology teacher
Duration: 10 x 50 minute lessons
When growing crop plants or breeding animals for food, farmers select the best animals and crops that suit their needs. This can be the best milking cow, highest-yielding crop or juiciest fruit. These characteristics are largely controlled by the plant's or animal's genes.
Sometimes, when you cross two plants, you can end up with what you want and the 'bonus' of something you don't. For example, you may get a plant that has juicy fruit but is also susceptible to disease. Sometimes these traits cannot be separated, and are said to be linked. Linked genes are found very close together on the chromosome. Extra crossbreeding may be able to separate them, but this takes time (often years). Often it may prove impossible to seperate them.
Plants and animals with desirable traits can also be bred using modern biotechnology and gene technology. The process can be more selective than conventional breeding, by both finding the genes that control a particular characteristic, and changing one specific characteristic at a time.
Reproductive technologies such as cloning can be used to produce identical organisms, each with a specific characteristic. This can produce herds of identical animals or fields of identical crop plants. Although the selected traits may be useful, one drawback of cloning a whole crop or herd of identical organisms is the risk of them succumbing to the same disease or a parasite.
Genetic diversity is nature's way of ensuring that some members of a species will be immune to a given threat, so that the species can survive.
In nature, different species cannot interbreed, so our ancestors selected and bred with characteristics within the species. Today, gene technology can be used to transfer genes from one species to another.
Genes can be transferred between species that have been separated for hundreds of millions of years by evolution (e.g. transfer of a gene from a bacterium into a plant). Therefore, a much greater range of traits can be bred into an agriculturally important species. This has led to a concern that gene technology allows scientists to ‘play God'.
Gene technology can be used in agriculture and food production to:
- increase crop or animal resistance to pests while reducing the use of chemicals
- increase crop or animal tolerance to chemicals that are used to kill harmful pests
- create disease resistance in crops and animals
- improve the food yield per plant or animal
- make plants and animals more suited to special environmental conditions such as drier regions or saline water
- improve the nutritional quality of the food produced by the plant or animal.
Researchers are using gene technology to develop potential benefits for the forestry and fishing industries.
In Australia, a lot of research focuses on the agriculture and food applications of gene technology. So far, commercial use of the products of this Australian research has been limited to Bt cotton, (also called Bollgard®II cotton), and five varieties of genetically modified (GM) carnation (Florigene Moon series). Australia is now involved in growing genetically modified canola.
The most common GM crops grown overseas are soybeans, corn, cotton, sugar beet, and beet grown for use in processed foods or in animal feed. Ninety-eight percent of GM crops are grown in four countries: Canada, the USA, Argentina, and China. Other countries that have approved GM crops include South Africa, Australia, Mexico, Bulgaria, Uruguay, Romania, Spain, Indonesia, Germany, India and the Philippines.
Products from these crops may be a part of the food we eat in Australia, if approved by Australia's food regulator.
Fish Genes in Tomatoes
Scientists once tried to transfer a gene from the Arctic flounder fish to tomatoes. It was hoped that transgenic tomatoes containing this protein could be used to produce products with better freezing quality, so that they could be frozen and thawed without going mushy.
The experiments failed to work. The antifreeze proteins were present in the tomato, but they did not improve the texture of the tomato fruit following freezing. No tomatoes with fish genes are actually in existence.
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