Chapter 11 - Genomes and gene technologies

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  • Chapter 11 - Genomes and gene technologies
    • Using gene sequencing
      • Tells us evolutionary relationships
    • Sequencing a genome
      • 4. Different lengths of DNA are separated using electrophoresis
        • This is where the DNA fragments are separated according to size
      • 3. DNA polymerase makes copies of DNA, stopping whenever a labelled nucleotide is added
      • 5. Computer records the labels
      • 2. Multiple labelled copies of each of the small lengths are made
      • 6. Computer program then works out the overall sequence
      • 1. Lots of copies are made using PCR, then broken apart
    • Genetic engineering
      • Creates GMO's
        • Example: E.coli that produce human insulin
        • Example: Golden rice tm
        • Example: pigs for xenotransplantation
      • Gene transfer
        • 3. Gene is inserted into a vector (usually a plasmid)
          • Plasmid is cut with the same restriction enzyme as the gene of interest and ligase is added to join the gene and plasmid together
        • 2. PCR
        • 4. Vector inserts gene into cells
          • Bacteria are treated with calcium ions to make them more likely to take up the plasmids
        • 1. Target gene is identified, and cut out of the chromosomes or made by reverse transcription of RNA
          • Gene is cut out using restriction enzymes (HGH uses BamH1) and has 'sticky ends'
        • 5. Successfully transformed cells are identified and clones
          • Either identified through antibiotic resistance (replica plating) or through fluorescence
    • PCR
      • 1. Mixture of DNA, primers, free nucleotides, and DNA polymerase is created
      • 2. DNA is denatured to make single strands (requires temp. of 95oC)
      • 3. Primers attach (anneal) to the ends (requires temp of 65oC)
      • 4. DNA polymerase builds up complete DNA strands (requires temp. of 72oC)
    • Probes
      • Labelled piece of DNA that anneals to the target gene so it can be identified
    • Gene therapy
      • Somatic therapy
        • Body cells are modified, modified genes cannot be passed on to offspring
      • Germ line therapy
        • Embryo modified and modified genes can be passed on
        • Banned in most countries including UK and USA


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