Presentation on theme: "Environmental Biology & Genetics Applied Genetics M r G R D a v i d s o n."— Presentation transcript:
Environmental Biology & Genetics Applied Genetics M r G R D a v i d s o n
Saturday, May 02, 20152Mr G Davidson Selective Breeding (Animals) Selective breeding is the selection of individuals, by man, with desirable characteristics and allowing them to breed. Individuals with undesirable characteristics are not allowed to breed.
Saturday, May 02, 20153Mr G Davidson Selective Breeding (Animals) Over a number of generations a significant improvement in the characteristics can be seen. e.g. the milk yield of dairy cattle has increased about three-fold in the last century.
Saturday, May 02, 20154Mr G Davidson Selective Breeding (Animals) Many environmental factors which influenced how a species evolved were removed when man domesticated or cultivated them. e.g. animals were provided with food. Animals were protected from predators. This allowed them to grow bigger and faster.
Saturday, May 02, 20156Mr G Davidson Selective Breeding (Plants) Man has also been selectively breeding plants. Superior varieties have been selected for breeding purposes. This has been achieved in maize plants (sweet corn).
Saturday, May 02, 20157Mr G Davidson Selective Breeding (Plants) Selected varieties are crossed in a process called hybridisation. The offspring, called hybrids, are fertile and these can then be further subjected to selective breeding.
Saturday, May 02, 20158Mr G Davidson Limitations of Selective Breeding Selective breeding relies on sexual reproduction which can cause problems for plant breeders such as: The desired characteristics may not be present. It is a long slow process. Fertilisation is not always guaranteed.
Saturday, May 02, 20159Mr G Davidson Genetic Engineering Genetic engineering is the transfer of DNA from one type of organism to another. The first organisms to have this done successfully were bacteria. Bacteria have one large chromosome in a ring and more smaller rings called plasmids.
Saturday, May 02, Mr G Davidson Genetic Engineering The genes on the chromosomes code for certain proteins. A useful gene can be removed from one organism and inserted into a plasmid, and the bacterium will now be able to produce the protein in a different organism, e.g. human insulin.
Saturday, May 02, Mr G Davidson Genetic Engineering
Saturday, May 02, Mr G Davidson Advantages of Genetic Engineering over Selective Breeding Genetic Engineering Selective Breeding Completely different species can be combined Only the same or very closely related species can be bred together Only desired characteristics are produced Some undesirable characteristics can show up Only takes one generation to get desired results Can take many generations to get desired results Large quantities of protein produced Limited quantities of protein produced Easier to purifyHarder to purify Less contaminationHigh risk of contamination
Saturday, May 02, Mr G Davidson Disadvantages of Genetic Engineering Inserting genes into animals and plants has proved to be very difficult. Some complex proteins can only be made by plants or animals. Only a few plants have been found that will accept the plasmids carrying the foreign gene.
Saturday, May 02, Mr G Davidson Disadvantages of Genetic Engineering Viruses have been used to insert genes but viruses can often cause harm to the cells. Syringes and projectiles have been used to insert the genes, but they often damage the cells, and often the inserted genes either only work for a short time or don’t work at all.
Saturday, May 02, Mr G Davidson Disadvantages of Genetic Engineering Sometimes an inserted gene can alter the biochemistry of the animal it is inserted into, and the result is harmful by-products being released. These side effects can be very difficult to detect and may even be longer term.
Saturday, May 02, Mr G Davidson Insulin Production The transferring of genes from one organism to another has lead to some very useful products being made. One excellent example of this is the production of human insulin. Insulin is a protein made in the pancreas which is a chemical messenger called a hormone.
Saturday, May 02, Mr G Davidson Insulin Production It acts on cells in the liver to convert excess sugar in the blood to glycogen which is then stored in the liver. Glycogen is a large insoluble molecule which can later be broken down to release the glucose when the body needs it.
Saturday, May 02, Mr G Davidson Insulin Production If a person cannot make insulin they suffer from diabetes and need to inject insulin. Before genetic engineering, insulin was extracted from pigs and cattle, and this was used in the treatment of diabetes. Nowadays the insulin is made by bacteria which have the gene for human insulin.
Saturday, May 02, Mr G Davidson Insulin Production It is extracted and purified before being used. Insulin made in this way is identical to human insulin and can be produced in vast quantities.
Saturday, May 02, Mr G Davidson Insulin Production Gene identified and cut out of chromosome using an enzyme. Plasmid extracted from bacterial cell. Plasmid cut open by an enzyme. Gene spliced into plasmid by an enzyme. Altered plasmid inserted into host bacterium. Plasmids duplicate. Insulin mass-produced
Saturday, May 02, Mr G Davidson Blood Many people donate blood. This blood can be used either as it is, or split up into its components, and used in operations. Blood can, however carry disease. There is a risk that the HIV virus can be transmitted.
Saturday, May 02, Mr G Davidson Blood Haemophilia is a blood disorder in which the blood fails to clot properly. This is caused by a lack of a blood clotting protein called factor VIII. This factor can be produced by genetic engineering. Unfortunately this process is extremely expensive.
Saturday, May 02, Mr G Davidson Fighting Disease The body protects itself from invading organisms by producing proteins called antibodies. The antibodies recognise the foreign organism and destroy it. The body can be stimulated to produce antibodies for particular diseases by vaccination.
Saturday, May 02, Mr G Davidson Fighting Disease Genetic engineering can produce proteins which act as vaccines, or even the antibodies themselves. These proteins can then be adapted so that they can be taken orally, resist the human digestive system and then be absorbed into the bloodstream.
Saturday, May 02, Mr G Davidson Gene Therapy Gene therapy is the replacement of a defective gene with a fully functional gene. Cystic fibrosis is one of the most common genetic disorders.
Saturday, May 02, Mr G Davidson Gene Therapy A defective gene is unable to produce a protein required for normal cell function and so the linings of the airways and pancreas become blocked with a very thick mucus. This defective gene has been identified and isolated.
Saturday, May 02, Mr G Davidson Gene Therapy Scientists are currently investigating ways of inserting the correct gene into the body cells. If this can be achieved, cystic fibrosis could be cured by gene therapy. Gene therapy is also being investigated for cancer.
Saturday, May 02, Mr G Davidson Gene Therapy Special genes called ‘suicide genes’ are placed into the cancer cells. These genes are only active in cancer cells – not normal cells.
Saturday, May 02, Mr G Davidson Gene Therapy They code for enzymes that can change harmless chemicals into toxins, which will then destroy the cancer cells. This type of gene therapy is fraught with difficulties such as: It is difficult getting the genes into the cancer cells. Using modified viruses to do this can result in diseases being inserted. In trials there have been some unexplained deaths.
Saturday, May 02, Mr G Davidson Genetically Modified Organisms These are organisms which have had genes inserted from another organism. These organisms are said to be genetically modified and are important in the development of new varieties of animals and plants.
Saturday, May 02, Mr G Davidson Genetically Modified Organisms These organisms are very beneficial in the search for new cures for diseases. Genetically modified organisms are also useful in improving the quality and quantity of food produced. It is easier to genetically modify plants than animals.
Saturday, May 02, Mr G Davidson Genetically Modified Organisms GM Crop ModificationBenefit Soya bean Resistance to weedkiller Increased yield Tomato Prevent softening Stays ripe longer Oilseed rapeProduce oilsUsed in plastics
Saturday, May 02, Mr G Davidson Genetically Modified Organisms Other improvements made to plants include: Drought tolerance Disease resistance Pest resistance Easier harvesting Richer in vitamins
Saturday, May 02, Mr G Davidson Future Developments The rapid expansion and developments in genetic modification have lead to public concern about a number of issues: The effect on the environment. Safety issues. Moral and ethical issues of whether this sort of practice is acceptable.
Saturday, May 02, Mr G Davidson Future Developments There are many other possible developments using genetic modification including: Developing crop plants and farm animals to make medicines. Developing organisms with organs which are not rejected on transplantation.