DNA Technology & Genetic Engineering

1. DNA Technology & Genetic Engineering Georgia Performance Standards: Examine the use of DNA technology in forensics, medicine, and agriculture. • Essential Questions: • How are genetically modified plants and animals made and used in medicine and agriculture? • How is DNA technology applied to solving problems?

2. Selective Breeding • Selective Breeding- a method of improving a species by allowing only those individual organisms with desired characteristics to produce to the next generation • Hybridization • Inbreeding

3. Hybridization: • Hybridization is a breeding technique that involves crossing different individuals to bring together the best traits of both organisms • Ex: combining the disease resistance of one plant with the food-producing capacity of another produces a hardier plant that increased food supply.

4. Inbreeding  • Inbreeding is the continued breeding of individuals with similar characteristics. • Used to maintain desired characteristics • Inbreeding helps to ensure that the characteristics that make each breed unique will be preserved. • Risks: Most of the members of a breed are genetically similar and genetic defects can arise.

5. Organism breed B Organism breed A Organism breed A Retains desired characteristics Combines desired characteristics Concept Map Selective Breeding consists of Inbreeding Hybridization which crosses which crosses Similar Organisms Dissimilar Organisms for example for example which which

6. Increasing Variation • Sometimes breeders want more variation than exists in nature.   • Breeders can increase the genetic variation in a population by inducing mutations, which are the ultimate source of genetic variability. • Radiation • Chemicals

7. Plant Breeding • Drugs used in plant breeding sometimes cause plants to produce cells that have double or triple the normal number of chromosomes. • Plants grown from such cells are called polyploidbecause they have many sets of chromosomes. • Polyploidy produces larger and stronger plants, which increase the food supply for humans.

8. Checkpoint Questions: • Give one example of selective breeding. • Relate genetic variation and mutations to each other. 3. How might a breeder induce mutations? 4. What is polyploidy? 5. Suggest ways that plants could be altered to improve the world’s food supply.

9. Manipulating DNA: • How are changes made to DNA?   • Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules. • Different techniques are used: • to extract DNA from cells • to cut DNA into smaller pieces • to identify the sequence of bases in a DNA molecule • to make unlimited copies of DNA.

10. Genetic engineering • Genetic Engineering - making changes in the DNA code of a living organism. • Process: • DNA extraction • Cutting DNA • Separating DNA • Reading the sequence • Cutting and pasting • Making copies Molecular Biology

11. DNA Extraction • How do biologists get DNA out of a cell? • DNA can be extracted from most cells by a simple chemical procedure: • The cells are opened and the DNA is separated from the other cell parts.

12. Cutting DNA • DNA molecules from most organisms are much too large to be analyzed, so biologists cut them precisely into smaller fragments using restriction enzymes. • Restriction enzymes cut DNA at a specific sequence of nucleotides. • Very precise

13. Restriction Enzymes Cut DNA • This drawing shows how restriction enzymes are used to edit DNA. • The restriction enzyme EcoRI, for example, finds the sequence CTTAAG on DNA. • Then, the enzyme cuts the molecule at each occurrence of CTTAAG. • Different restriction enzymes recognize and cut different sequences of nucleotides on DNA molecules. VIDEO

14. In gel electrophoresis, a mixture of DNA fragments is placed at one end of a porous gel, and an electric voltage is applied to the gel. When the power is turned on, DNA molecules, which are negatively charged, move toward the positive end of the gel. The smaller the DNA fragment, the faster it moves. Uses: Comparing genomes of different organisms or individuals. Locating and identifying one particular gene out of the millions of genes in an individual’s genome. Separating DNA 

15. Gel Electrophoresis Separates DNA Power source DNA plus restriction enzyme Longer fragments Shorter fragments Mixture of DNA fragments Gel

16. In order to study genes, biologists often need to make many copies of a particular gene. A technique known as polymerase chain reaction (PCR) allows biologists to make copies of DNA. PCR Process: 1. DNA is heated to separate strands 2. DNA is cooled to allow primers to bind 3. DNA polymerase copies the strands Making Copies

17. PCR: Polymerase Chain Reaction makes copies of DNA

18. DNA fingerprinting • The pattern that results from gel electrophoresis is known as as DNA finger print. • The more similar the DNA fingerprints of two organisms, the more recently they shared a common ancestor.

19. DNA fingerprinting • Analysis of sections of DNA that have little or no known function, but vary widely from one individual to another, in order to identify individuals • The reliability of DNA evidence has helped convict criminals as well as overturn many convictions.

20. - The technicians place a DNA fingerprint from a known person next to a DNA fingerprint found at the scene of the crime. - If the DNA fingerprints match, the person can be placed at the scene of the crime.

21. It is easy to see in this example that daughter 2 is the child from the mother’s previous marriage and son 2 is adopted. • You can see that both daughter 1 and son 1 share RFLPs with both the mom and dad (colored blue and yellow respectively), while daughter 2 has RFLPs of the mom but not the dad, and son 2 does not have RFLPs from either parent. • - Even if the RFLPs were not color coded, you could still distinguish the parents of the children by looking at the position of the bands in the agarose gel. In reality, all of the bands look the same and only the positions are different.

22. Genetics and Biotechnology Chapter 13 13.2 DNA Technology • To understand how DNA is sequenced, scientists mix an unknown DNA fragment, DNA polymerase, and the four nucleotides—A, C, G, T in a tube.

23. Genetics and Biotechnology • Every time a modified fluorescent-tagged nucleotide is incorporated into the newly synthesized strand, the reaction stops. Chapter 13 13.2 DNA Technology • Each nucleotide is tagged with a different color of fluorescent dye.

24. Genetics and Biotechnology Chapter 13 13.2 DNA Technology • The sequencing reaction is complete when the tagged DNA fragments are separated by gel electrophoresis.

25. Reading a DNA Sequence Figure 22.3

26. Deriving a DNA Sequence Figure 22.4

27. Checkpoint Questions: • Describe the process scientists use to manipulate DNA. 2. Why might a scientist want to know the sequence of a DNA molecule? 3. How does gel electrophoresis work? 4. Which technique can be used to make multiple copies of a gene? What are the basic steps in this procedure? 5. How is genetic engineering like computer programming?

28. Cell Transformation • During Cell Transformation, a cell takes in DNA from outside the cell. • Plant and animal • This external DNA becomes a part of the cell’s DNA. • One way to make recombinant DNA is to insert a human gene into bacterial DNA. • The new combination of genes is then returned to a bacterial cell, and the bacteria can produce the human protein. • video

29. Cutting and Pasting  • Enzymes make it possible to take a gene from one organism and attach it to the DNA of another organism. • Such DNA molecules are sometimes called recombinant DNA because they are produced by combining DNA from different sources.

30. Transforming Bacteria • Recombinant DNA is used. • The foreign DNA is first joined to a small, circular DNA molecule known as a plasmid. • Plasmids have a DNA sequence that serves as a bacterial origin of replication. • Plasmids have a genetic marker—a gene that makes it possible to distinguish bacteria that carry the plasmid from those that don’t.

31. Transforming Bacteria

32. Plant Cell Transformation • Recombinant plasmids can be used to infect plant cells. • DNA can also be injected directly into some plant cells. • Cells transformed by either procedure can be cultured to produce adult plants.  

33. Plant Cell Transformation Agrobacterium tumefaciens Gene to be transferred Cellular DNA Inside plant cell, Agrobacterium inserts part of its DNA into host cell chromosome Recombinant plasmid Plant cell colonies Transformed bacteria introduce plasmids into plant cells Complete plant is generated from transformed cell

34. Checkpoint Questions: • What is transformation? • How can you tell if a transformation experiment has been successful? 3. How are genetic markers related to transformation? 4. What are two features that make plasmids useful for transforming cells? 5. Compare the transformation of a prokaryotic cell with the transformation of a eukaryotic cell.

35. Applications of Genetic Engineering • Scientists have developed many transgenic organisms, which are organisms that contain genes from other organisms. • scientists have removed a gene for green fluorescent protein from a jellyfish and tried to insert it into a monkey.

36. Applications of Genetic Engineering • Transgenic animals are often used in research. • What might be the benefit to medical research of a mouse whose immune system is genetically altered to mimic some aspect of the human immune system? • Transgenic plants and animals may have increased value as food sources. • What might happen to native species if transgenic animals or plants were released into the wild?

37. Transgenic Organisms: • The universal nature of genetic mechanisms makes it possible to construct organisms that are transgenic, meaning that they contain genes from other organisms. • A gene from one organism can be inserted into cells from another organism. • These transformed cells can then be used to grow new organisms.

38. Transgenic Bacteria or Yeast: • Transgenic bacteria reproduce rapidly and are easy to grow. • Therefore they now produce a host of important substances useful for health and industry. • human insulin, growth hormone, and clotting factor

39. Transgenic Animals: • Transgenic animals have been used to study genes and to improve the food supply • Strains of mice • produced with human genes that make their immune systems act similarly to those of humans. • study the effects of diseases on the human immune system. • Transgenic livestock • produced with extra copies of growth hormone genes. • such animals grow faster and produce meat that is less fatty than that from ordinary animals. • Transgenic chickens • resistant to the bacterial infections that sometimes cause food poisoning.

40. Transgenic plants help to increase our food supply. Genes produce a natural insecticide (this avoids synthetic pesticide use). Genes that enable them to resist weed-killing chemicals (allows farmers to grow more food by controlling weeds. Human antibodies that can be used to fight disease; Plastics that can now be produced only from petroleum Foods that are resistant to rot and spoilage. Transgenic Plants:

41. Cloning: • A clone is a member of a population of genetically identical cells produced from a single cell. • Cloned colonies of bacteria and other microorganisms are easy to grow, but this is not always true of multicellular organisms, especially animals.

42. Cloning: • Clones are used for medical and scientific value, but also causes ethical issues. • In 1997, Scottish scientist Ian Wilmut stunned biologists by announcing that he had cloned a sheep

43. Cloning A body cell is taken from a donor animal. An egg cell is taken from a donor animal. The nucleus is removed from the egg. The body cell and egg are fused by electric shock. The fused cell begins dividing, becoming an embryo. The embryo is implanted into the uterus of a foster mother. The embryo develops into a cloned animal.

44. Cloning of the First Mammal Section 13-4 A donor cell is taken from a sheep’s udder. Donor Nucleus These two cells are fused using an electric shock. Fused Cell Egg Cell The nucleus of the egg cell is removed. An egg cell is taken from an adult female sheep. The fused cell begins dividing normally. Embryo Cloned Lamb The embryo is placed in the uterus of a foster mother. The embryo develops normally into a lamb—Dolly Foster Mother Go to Section:

46. Checkpoint Questions: 1. List one practical application for each of the following: transgenic bacteria, transgenic animals, transgenic plants. 2. What is a transgenic organism? 3. What basic steps were followed to produce Dolly? 4. List reasons you would or would not be concerned about eating genetically modified food.

47. The Human Genome Project: • The Human Genome Project is an attempt to sequence all human DNA. • VIDEO

48. Gene Therapy • Curing genetic disorders by gene therapy. • Gene therapy is the process of changing the gene that causes a genetic disorder.   • In gene therapy, an absent or faulty gene is replaced by a normal, working gene. • This way, the body can make the correct protein or enzyme it needs, which eliminates the cause of the disorder.

49. Figure 14-21 Gene Therapy Section 14-3 Bone marrow cell Nucleus Normal hemoglobin gene Chromosomes Bone marrow Genetically engineered virus Go to Section:

50. Checkpoint Questions: • What is the Human Genome Project? • Describe how gene therapy works. 3. Name two common uses for DNA testing. 4. Describe how molecular biologists identify genes in sequences of DNA. 5. Do you think it should be legal for people to use genetic engineering to affect their children’s characteristics? Give reasons for your answer.