Evolution & Gen. Engineering

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Evolution & Gen. Engineering

  1. 1. 8.1 Development of the Phenotype Today’s Learning Objectives:  State the two influences on the phenotype of an organism.  Give examples of how environment can influence the phenotype of human identical twins during growth.  Give examples of how environment can influence the phenotype of humans after growth is complete.  Explain why changes in the phenotype caused by the environment are not important in evolution of new species.
  2. 2. Genotype is not the only influence on phenotype. Phenotype is also dependant on the environment which the organism has grown and developed. GENOTYPE + ENVIRONMENT = PHENOTYPE
  3. 3. 8.2 Natural Selection and Evolution Today’s Learning Objectives:  Describe how organisms such as mice, can produce more offspring than can survive.  List some factors which prevent all offspring from surviving.  State why organisms such as mice are not genetically identical.  State the meaning of the term ‘natural selection’.  State the meaning of the term ‘evolution’.  Describe the role of natural selection in evolution.  Describe the evolution of cichlid fish in Lake Victoria.
  4. 4. Breeding and Survival Starvation - Not good at competing for food Disease -weaker offspring Predators -poorly camouflaged -slow reactions Exposure -Thinner coats - not good at competing for shelter Only rabbits with the best characteristics will survive.
  5. 5. Only organisms with the best combination of genes for their environment will survive. This means that their gene combinations will be passed on to the next generation. Organisms with less useful genes will die out and therefore not pass on their genes. This process is known as Natural Selection. If natural selection operates over millions of years it can give rise to new species… EVOLUTION!!
  6. 6. 8.3 Natural Selection- A Case Study Today’s Learning Objectives:  Describe the adaptation of the speckled form of the peppered moth.  State the meaning of the term melanic.  Explain why the melanic moths usually failed to pass on their genes in the early 19th Century.  Describe the effects of the burning of coal on lichens and on exposed surfaces.  Describe how natural selection changed the survival chances for melanic moths in industrial areas.  State why the varieties of the peppered moth have not become two species.
  7. 7. The Peppered Moth Speckled Variety Melanic Variety -A nocturnal insect, rests on tree surfaces during the day. -Is preyed upon by insect eating birds which pick them up from exposed surfaces.
  8. 8. •In the early 19th century the speckled moths were well adapted to camouflage themselves against the lichen covered tree and avoid predation. •The melanic version (all black) showed up against the lichens and were easier for birds to spot. Melanic version rarely survived to pass on genes.
  9. 9. •The Industrial revolution (late 19th century) saw the use of coal burning industry. Sooty smoke and sulphur dioxide was lethal to lichens and covered exposed surfaces. •Speckled moths were now easier to spot and the melanic moths had a greater chance of survival to pass on their genes.
  10. 10. 8.4 Selective Breeding Today’s Learning Objectives:  Define the term ‘selective breeding’.  Give examples of animals which have been selectively breed.  Give examples of characteristics in farm animals that have been improved by selective breeding.  State the meaning of the term ‘hybridisation’.  State some of the limitations or problems of selective breeding.
  11. 11. The process of natural selection has led to great biodiversity. For many centuries, humans have also altered the characteristics of organisms by deliberately choosing which individuals to breed: SELECTIVE BREEDING This involves breeding desirable characteristics to produce them in the next generation. e.g Animals Cattle for milk and beef Sheep for wool Poultry for egg production
  12. 12. Limitations of Selective Breeding -New combinations are limited to the genes that the organism naturally possesses. The gene for a desired characteristic may not be present. -Difficulties in getting selected individuals to breed. -May take months or years to achieve one generation. -Fertilisation = random variation, so hybrids by chance may have an inferior combination of genes. -Can increase the frequency of recessive (often inferior) genes. Relies on sexual reproduction:
  13. 13. 8.5 Genetic Engineering Today’s Learning Objectives:  Define the term ‘genetic engineering’.  State what the genes of an organism are made of.  Describe how plasmids are used in genetic engineering.  State which organisms are most commonly used to make useful products in genetic engineering.  State some advantages of genetic engineering compare to selective breeding.  State some of the disadvantages of genetic engineering.
  14. 14. Artificial Selection Selective Breeding Traditional method Genetic Engineering Modern method Genetic engineering is the transfer of DNA from one type of organism to a different organism.
  15. 15. Insulin gene cut and removed from human chromosome. Human chromosome Insulin gene Plasmid removed from bacterial cell Human insulin gene placed into bacterial plasmid.
  16. 16. Plasmid containing insulin gene placed into new bacterial cell Plasmid multiplies inside bacterial cell. More insulin is produced Bacterial cell grows and divides producing more cells containing many more plasmids and much more insulin Human insulin is collected and purified from bacterial cell
  17. 17. Advantages of Genetic Engineering:  DNA from completely different species can be combined.  Recessive genes not a problem, desired characteristics can be specifically selected.  Can produce large quantities of desired proteins (e.g. Insulin) which are easy to purify and not contaminated.  Only needs one generation to produce results.
  18. 18. Disadvantages of Genetic Engineering:  Multicellular animals are much more complex than bacteria – only a few plant cells are able to take up plasmids.  Inserting genes using syringes instead can often damage the cell and the inserted genes often only work for a short time.  Inserting new genes into an animal may affect it’s biochemistry so that it is producing harmful by- products or long term effects.
  19. 19. 8.6 Uses of Genetic Engineering Today’s Learning Objectives:  Describe how insulin is produced by genetic engineering and state the advantages of producing it.  State the meaning of the term ‘haemophilia’.  State the advantages of producing blood-clotting proteins by genetic engineering.  Describe how genetic engineering could help people with defective genes.  Explain how genetic engineering can help fight disease.  Name some plants used to make oral vaccines.  Nam the type of medically useful substances which can be produced in the milk if genetically engineered animals.
  20. 20. Insulin Used to treat diabetes Animal Insulin Extracted from pancreas of cattle and pigs. Similar to human insulin but not identical Injected to treat diabetes. Works well but can be seen as a foreign protein and trigger an allergic reaction. Genetically Engineered Insulin Gene for human insulin isolated and inserted into a bacterium. Bacteria grow and multiply and produce human insulin. Insulin purified and injected to treat diabetes. Identical to human insulin so does not cause allergic reactions.
  21. 21. 8.7 Issues in Genetic Engineering Today’s Learning Objectives: State the meaning of the term ‘Gene Therapy’. Explain how gene therapy could lead to a cure for cystic fibrosis. State the meaning of the term genetically modified organism. Give examples of improvements that can be seen in GM crops. State some problems with GM crops. State the meaning of the terms ‘pharming’ and ‘xenotransplantation’.
  22. 22. Gene therapy is the replacement of a defective gene, which causes a genetic disorder, with a functional gene. A genetically modified organism is an organism which has had genes inserted from another organism. The development of crop plants and farm animals to make medically useful products is called ‘pharming’, short for pharmaceutical farming. GM animals could be developed with organs that would not be rejected when transplanted into humans. This is called xenotransplantation.

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