Dna technology 1

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Dna technology 1

  1. 1. DNA Technology05/25/12 cott
  2. 2. What makes one allele different from another allele? All alleles for a particular gene contain DNA instructions for the synthesis of the same protein BUT…slight differences in the base sequences of two alleles, such as:  AGGCTTAGA, vs.  AGGCTAAGA  Can cause slight differences in the protein produced by the alleles05/25/12 cott
  3. 3. Example: TRAIT: BLOOD CLOTTING GENE: CLOTTING FACTOR LOCUS X CHROMOSOME ALLELES: ACGGTACT (XH - normal) ACGATACT (Xh - hemophilia)05/25/12 cott
  4. 4. How is the genetic code translated into protein structure? Proteins are chains made of many amino acids linked together The sequence of amino acids is specified by the base sequence of the DNA…each sequence of 3 bases codes for a different amino acid GAC ACA CAG GGG AAG DNA Chain of amino acids05/25/12 cott
  5. 5. DNA Technology: Genetic Engineering Scientists use knowledge of structure of DNA to study and change DNA molecules Uses tools:  DNA extraction – removing DNA  Restriction enzymes – cutting DNA  Gel electrophoresis – separating DNA  PCR  DNA Fingerprinting05/25/12 cott
  6. 6. DNA Extraction Place cells in detergent to break down membranes Place cell extract in ethanol  DNA is insoluble in ethanol, so it comes out of solution, and can be removed for study05/25/12 cott
  7. 7. Restriction Enzymes – Cutting DNA Enzymes that recognize a particular short DNA sequence, and then cut the DNA strand within that sequence. 1st discovered in bacteria which use the enzymes to cut and destroy viral DNA. DNA molecules are too large to be analyzed as a whole.05/25/12 cott
  8. 8. Restriction Enzymes Eco RI – restriction enzyme found in E. Coli. EACH RESTRICTION ENZYME RECOGNIZES A DIFFERENT SEQUENCE OF DNA AND WILL CUT THAT SEQUENCE ONLY!!! DNA Restriction - a MAD GOOD ANNY!05/25/12 cott
  9. 9. Restriction Enzymes Staggered CutStaggered (Eco Ri) cut 5’ - GAATTC – 3’ 3’ - CTTAAG – 5to produce sticky ends: 5’ G AATTC – 3’ 3’ CTTAA G – 5’05/25/12 cott
  10. 10. Restriction Enzymes Blunt CutBlunt Cut: 5’ – GTTAAC – 3’ 3’ – CAATTG – 5’Blunt Ends: 5’ GTT AAC – 3’ 3’ CAA TTG – 5’Blunt ends can be attached to any other DNA that produces blunt ends.05/25/12 cott
  11. 11. Restriction Enzymes Example: Enzyme called EcoR I Cuts DNA anywhere it finds sequence TTAA05/25/12 cott
  12. 12. Gel Electrophoresis Means of separating, by size, the DNA fragments produced by restriction enzyme cuts. Compares genes of different individuals or organisms05/25/12 cott
  13. 13. Gel Electrophoresis1. DNA fragments placed into wells in gel slab2. Electric voltage is applied to gel.3. DNA (negatively charged) migrates to (+) end of gel.4.05/25/12 Smaller the fragment, faster and farther it moves. cott
  14. 14. Cell Transformation  What happens during cell transformation?  How can you tell if a transformation experiment has been successful?05/25/12 cott
  15. 15. Plasmid Small DNA molecules found naturally in bacteria. Useful for DNA transfer. WHY?  It has a DNA sequence.  If a plasmid containing foreign DNA gets into a bacterial cell >>>>> replication occurs.05/25/12 cott
  16. 16. Recombinant DNA Plasmids have genetic markers Make it possible to distinguish foreign DNA05/25/12 cott
  17. 17. Recombinant DNA If transformation is successful DNA is combined (recombinant) into on of the chromosomes of the cell. Applications for genetic engineering:  Create human forms of protein >>> insulin, HGH, clotting factor.  Cloning05/25/12 cott
  18. 18. 05/25/12 cott
  19. 19. DNA Fingerprinting A practical use of DNA technology05/25/12 cott
  20. 20. DNA Fingerprinting Just as no two people have the same fingerprint, no two people (except identical twins) have same DNA.05/25/12 cott
  21. 21. DNA Fingerprinting Differences between individuals due to different sequences of nucleotide bases  Remember, different alleles are result of differences in base sequences  Ex: AACTGGCA vs. AACCGGCA05/25/12 cott
  22. 22. DNA Fingerprinting In addition, between genes, chromosomes contain large amounts of DNA repeats  Do NOT code for proteins  Example: AAAATTTTAAAATTTT, etc. Number of repeats between genes varies from person to person05/25/12 cott

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