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IB Genetics Topic 4:

IB Genetics Topic 4:. Genetic Engineering. Topics in Genetic Engineering. Polymerase Chain Reaction (PCR) Gel electrophoresis DNA profiling The genome project Gene transfer Genetic modification in plants and animals Cloning. We will be brief!.

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IB Genetics Topic 4:

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  1. IB Genetics Topic 4: Genetic Engineering

  2. Topics in Genetic Engineering • Polymerase Chain Reaction (PCR) • Gel electrophoresis • DNA profiling • The genome project • Gene transfer • Genetic modification in plants and animals • Cloning

  3. We will be brief! • The Blog has videos and games for you to cement your understanding of each topic!

  4. 4.4.1: The Polymerase Chain Reaction • Kary Mullis, 1984, Nobel Prize 1993 • ‘Reviewers and Biographers often latch on to his enjoyment of drugs, womanising and surfing to paint him as some sort of cool rock star rebel…but…’

  5. What does PCR do? • It quickly amplifies a tiny sample of DNA into millions of identical copies • This produces enough DNA to allow further analysis and study.

  6. The DNA sequences amplified by PCR are used for: • Forensic identification - crime (CSI….) • Paternity suits • The Genome project: determination of the entire human genetic code • Diagnosing diseases and genetic disorders – genotype analysis • Detection of bacteria and viruses in the environment • Evolutionary research

  7. How does PCR work? First, you need to extract DNA from cells. Next, PCR requires: • Custom-made DNA primers • (TAQ) DNA polymerase • Nucleotides for complementary base pairing • HEATING and COOLING: Thermocycler machine PCR can produce 100 billion copies of the DNA sample in a few hours

  8. Let’s do it! • PCR the movie • PCR the cartoon • PCR the game

  9. 4.4.2: Gel electrophoresis • Commonly the DNA sample is first amplified by PCR • The DNA sample is chopped into fragments using restriction enzymes • Gel electrophoresis separates fragments of DNAaccording to their size • DNA samples are placed in a gel, fluorescent marker added (tag attached to a triplet), and an electric charge is applied to push fragments along • The shortest fragments travel furthest through the gel, while the longest (heaviest) remain closer to their origin • This lets us ‘match’ the sample against another DNA sample or standard

  10. Let’s do it! • Virtual Lab 1 • Virtual lab

  11. 4.4.3: DNA profiling HOW? APPLICATIONS Numerous techniques for DNA profiling: Criminal forensics Paternity suits Ecology – identifying relationships in migrating birds, whales etc Evolutionary genetics • DNA sample (blood, semen, cheek swab) • Sample is amplified by PCR, then matched against known samples using gel electrophoresis • We look for standard tandem repeating DNA: highly repetitive sequences from non-coding region of DNA • STR’s are unique to individuals

  12. Famous examples of DNA profiling • The innocence project • The famous blue dress • Identifying the Mona Lisa • Identifying the Romanovs

  13. DNA profiling: paternity and forensics • The fluorescent banding pattern shows up for each DNA fragment and can be compared with test/ known sample • Usually >4 ‘STR’ sites are used to establish paternity or identity

  14. 4.4.6: The Human Genome project We’re all the same! We’re all different! Welcome to the human genome

  15. Started in 1990, first draft published in 2003, ongoing refinement… Amazing international effort • The BBC tell us about the genome 10 years on • Hank tells us some surprises about the human genome project • ..so what has the human genome project achieved, so far?

  16. Key outcomes of the Human Genome project • We identified the number (30,000) and loci of all the genes of our genome 1. Human health: Medical diagnostics, treatments, pharmacogenomics, gene therapy • We identified many new proteins and their functions 2. Transgenics: move production of beneficial proteins from one species to another, design novel proteins • We compared human DNA with that of other species 3. Evolutionary genetics and evolutionary history 4. Bio-informatics: Genetic databases and the bio-informatics industry

  17. The HGP and human health • 2 out of 3 of us will die of a genetically related disease • Many (some say all) diseases have a genetic cause • Genetic report cards can identify ‘potential risk’ of future illnesses • The future is here...

  18. Do you want to know your genome? Do you want to know your genome? Are you sure?

  19. The human genome and new medicine (1): Gene therapy • Find defective genes and ‘fix them’ • Insert a healthy normal gene or gene product (lipid, protein)to achieve normal function • Most effective for single gene disorders: cystic fibrosis, Sickle Cell disease, • gene therapy in depth • A lucrative business...

  20. The human genome provides avenues for new medicines • Identify beneficial molecules which are produced in healthy people • Identify the gene which produces the desirable molecule • Copy that gene and use it as a recipe to synthesise the molecule in a laboratory (or in another organism!) • Distribute the beneficial molecule as a new treatment

  21. The HGP and medicine (3): Pharmacogenomics Uses information about your genetic make-up to determine the drug, and drug doses, that will work best for you Currently used for treatment of: • HIV • Breast cancer • Colon cancer • Mental illness more info here...

  22. 3. Using the HGP to understand human evolution By sequencing and databasing genes, we can see similarities and differences between species • The closer the genome match, the closer their evolutionary history • Human Chromosome 2 came from fusion of two great ape chromosomes • Karl Miller on human evolution • The time-tree of evolution

  23. Ethics and the human genome How companies are patenting your genetic code

  24. 4.4.8: GENETIC ENGINEERING, (MODIFICATION, TRANSGENICS)BIOTECHNOLOGY

  25. The basic premise for genetic engineering… The genetic code is universal • All living things share the same code • Each codon codes for the same animoaacid, regardless of the species • Genes can be transferred from species to species, to produce the same product We can cut, copy and paste DNA between species

  26. Gene transfer 101: the basics of cutting, copying, pasting and cloning genes • An introduction • Step-by-step

  27. How does genetic engineering work? • Cut out desired DNA using restriction endonuclease • Prepare plasmid using the same restriction enzyme • Insert DNA into plasmid using DNA ligase • Insert plasmid (vector) into host cell

  28. Applied gene transfer: Gene Therapy Gene therapy for treatment of Severe Combined Immunodeficiency Disease (2)

  29. Genetic Engineering: Making Human insulin • E. Coli make human insulin

  30. Genetic Engineering: Making Factor IX in sheep… 1997: Factor IX isolated and purified from sheep’s milk to treat one hereditary form of haemophilia (Haemophilia B, Christmas Disease)

  31. Polly and Molly the Factor IX sheep

  32. Transgenic (GM) plants

  33. Transgenic plants: The controversies… The controversies….

  34. Transgenic (GM) animals

  35. Glowing animals?....what’s the big deal? Worth a Nobel prize….

  36. Further Applications of Transgenic Technology • Vaccines (transgenic yeast produces vaccine for Hepatitis B) • Transgenic mice widely used for human disease research • Transgenic male mosquitoes carrying ‘lethal gene’ used to reduce the incidence of Dengue fever

  37. Genetic modification: the PROs… • GM crops should improve yields, quality and food security • Pest-resistant crops will reduce the need for pesticides • GM can produce crops which provide dietary supplements such as retinol • GMO’s used to produce rare proteins for medicine or vaccines will be cheaper and less polluting than conventional methods • GM allows farmers greater control for selective breeding of crops and animals

  38. Genetic modification: the CONs… • No one knows the long-term effects of GMO’s in the biosphere PRECAUTIONARY PRINCIPLE • Genes from GM crops are easily integrated into the wild type crop • Genes may be able to cross species • Crops which produce toxins to kill insects could prove toxic to humans • Large portions of the human food supply may fall under the control of a small number of companies • High-tech agricultural ones are not necessarily better than simpler solutions • A proliferation of GMO’s could drastically reduce natural biodiversity

  39. Where do you stand?

  40. 4.4.11: CLONING

  41. What is a clone? • A group of genetically identical organisms • A group of cells artificially derived from a single parent

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