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mutations & mitosis

mutations & mitosis. 24 January 2012. recap. Our genetic information is stored in DNA Specific genetic sequences code for specific polypeptides DNA is semi-conservative Given the sequence one side of the DNA double helix, can determine the corresponding sequence on the other side

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mutations & mitosis

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  1. mutations & mitosis 24 January 2012

  2. recap • Our genetic information is stored in DNA • Specific genetic sequences code for specific polypeptides • DNA is semi-conservative • Given the sequence one side of the DNA double helix, can determine the corresponding sequence on the other side • A – T ; C – G

  3. for example A T G C A C C G G T A C | | | | | | | | | | | | T A C G T G G C C A T G

  4. recap • specific gene sequences to produce a polypeptide are ‘read’ on a strand of DNA  transcribed into mRNA • (DNA double stranded, RNA single) • A – U (uracil) • C – G • G – C • T – A

  5. for example A T G C A C C G G T A C | | | | | | | | | | | | U A C G U G G C C A U G | | | | | | | | | | | | T A C G T G G C C A T G

  6. recap • mRNA leaves nucleus, translated into polypeptide at ribosome • each 3-nucleotide sequence corresponds to a specific amino acid • eg. AUG  methionine

  7. mutations & mitosis 24 January 2012

  8. question/discussion: • A fish has a mutation in its genome that causes it to fluoresce bright green under certain wavelengths of light. Is this a positive, negative, or neutral mutation? Explain. • How could the fish be ‘treated’ so it no longer fluoresces?

  9. mutations • deletion (base missing) • addition (extra base added) • substitution (base substituted for another)

  10. mutations • Positive Mutations • When a gene mutation benefits the individual. • Negative Mutations • When a gene mutation harms the individual • Neutral Mutation • When a gene mutation has no effect on the individual

  11. A litter of glowing kittens, produced at the Mayo Clinic, could provide scientists with new methods for studying AIDS. Eric Poeschla and collaborators developed a highly efficient method for genetically engineering cats. They inserted genes—including a gene that glows green—into the eggs of domestic cats prior to fertilization and showed these genes were expressed throughout the body of the resulting animals. The fluorescent cats passed these genes onto their offspring, who also glowed.

  12. gene therapy • Gene therapy is complicated and experimental: • A virus in engineered to carry a normal gene • The virus must somehow be targeted to the cells with the defective gene • The normal gene must then replace the defective gene • The normal gene must then be “switched on” so that the replacement normal gene produces the proper healthy proteins. It is also important that the normal gene make the correct amount of healthy protein.

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