Session 3 Outline

The students will already have learned about genes and chromosomes
And they will have seen worm mutants
1. Review (Al)
  • Punnett square - Sickle Cell Anemia
  • Recessive mutations
  • Mitosis
  • Chromosomes
  • Genes - instructions; part of a chromosome
2. Genes contain information (Drew)
  • Cell as a factory
    • Factory has a machine that can make any product
    • Factory has the instructions needed to make each product (genes)
    • In each factory, only some of the instructions are used
  • Hereditary skin disease in man - consequence of faulty instructions
3. DNA (Drew/Bob)
  • A chromosome is a strand of DNA
  • A gene is a stretch of DNA
  • DNA is made up of four "bases:" G,A, T and C
  • The information in a gene is "written" as a string of three-letter words (GCA, TGT, AAC and so on)
  • A mutation is a change (misspelling) in a gene
4. Worm mutants: rol-6 (Bob)
  • A gene product found in worms and humans in collagen
    • Structural protein
  • In humans:
    • Collagen is part of connective tissue (joints, skin, blood vessels) and bones
    • Many human diseases are caused by mutations in collagen genes
      • Osteoporosis
      • Osteoarthritis
  • In the worm:
    • Collagen is part of the worm 's cuticle (skin)
    • The cuticle gives the worm its shape
  • Rol-6: the worm's body is twisted into a corkscrew shape, so worm moves in a circle (overhead shoeing alae)
  • Sequence of rol-6 gene and mutant change
5. How is knowing which gene is defective useful? (Al)
  • Identification of people predisposed to disease - early detection + treatment
  • Replace defective gene - "Bubble Boy Disease"