DNA replication
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DNA replication






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DNA replication DNA replication Presentation Transcript

  • Unit B5 & 6: Cell Biology (DNA Replication ) Authored by Michelle Choma ©
    • Students who have fully met the prescribed learning outcomes (PLO’s) are able to:
    • B5. Describe DNA replication.
    • Describe the three steps in the semi-conservative replication of DNA:
      • “ unzipping” (DNA helic ase )
      • complementary base pairing (DNA polymer ase )
      • joining of adjacent nucleotides (DNA polymer ase )
  • This is it!! Short one Eh!?
    • Describe the purpose of DNA replication.
    • Identify the site of DNA replication within the cell.
    • B6. Describe recombinant DNA.
    • Define recombinant DNA.
    • Describe a minimum of three uses for recombinant DNA.
  • Introduction
    • Recall the structural composition and functions of DNA. See B4
  • DNA Replication
    • Purpose :
    • Before a cell divides, it needs to double the number of chromosomes (containing genes/traits, codons/protein codes)
      • i.e. the DNA is duplicated for each new daughter cell.
  • Location :
    • Nucleus, mitochondrion (and plant chloroplasts); requires 2 enzymes helic ase and DNA polymer ase .
    Helicase DNA Polymerase
  • Products :
    • 2 DNA molecules; 1 identical to original.
    • This is known as semiconservative replication , which produces two “half-old and half-new” DNA strands.
  • 3 basic steps:
    • 1.) Unzipping
    • 2 strands of DNA unwind AND unzip the H-bonds between N-base pairs using helic ase .
  • Next step
    • 2.) Complementary base pairing
    • New nucleotides present in the nucleus (T, C, A, G) bond with the complementary pairs on the parental strand
      • i.e. A-T, G-C, T-A, and C-G using DNA polymer ase
  • And lastly….
    • 3.) Joining of adjacent nucleotides
    • Adjacent nucleotides join/form a bond with the help of DNA polymer ase (“proof-reader”) to form new sugar-phosphate backbones resulting in 2 identical DNA molecules. This is referred to as semi-conservative .
  • Recombinant DNA (rDNA)
    • Definition:
    • DNA/genome from two different organisms are spliced together to obtain a desired trait/characteristic or perform a specific function; the manipulation of a genome from two or more sources, such as bacteria, plants or animals.
      • E.g. Bacteria nucleic acid containing a human hormone gene and producing biotechnology products, i.e. insulin, growth hormone.
  • Uses:….there are lots!
    • Production of hormones (insulin, growth hormone), human proteins (interferon, antibodies) and vaccines from bacteria.
    • Development of pest-resistant, frost-resistant, disease-resistant, altered oil content and ripening etc. in crops. Plants can also be engineered to produce human hormones, proteins, and antibodies.
    • Production of DNA probes for paternity/maternity, body ID at crime scenes, evolutionary relationships etc.
  • Some more
    • Transgenic animals, or genectically altered organisms (GMO’s) to increase productivity, produce pharmaceuticals, produce organs, research in cancer/tumour cells etc.
    • Transgenic bacteria used for vaccines, biofilter airborne pollutants, synthesize hormones, enzymes for making cheese, clean oil spills, extract precious metals in mining.
    • In medicine for the diagnosis and treatment of genetically inherited disorders, e.g. cystic fibrosis
    • To give an organism a metabolic capability it did not possess before.
    • To create more copies of a specific gene so it can be studied.
  • What do this fish and
  • This ice cream have in common?
  • mmmmm……smooth ice cream
    • “ Anti-freeze” gene from arctic pout are inserted into a yeast which then generates the anti-freeze protein
    • This protein is added to ice cream to make it smoother (smaller ice crystals)
    • Hmmmm…. Is this a good idea? What do you think?