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CHAPTER 14

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					   CHAPTER 14:

MENDELIAN GENETICS AND
     INHERITANCE
         GREGOR MENDEL
• Born July 20, 1822 in
  Heinzendorf (Austria)
• As a child, gardened
  and kept bees to
  entertain himself
• Joined Abbey of St.
  Thomas (Brno) in
  1843; occupied spare
  time with gardening
• Mendel soon
  discovered that            The Gene Idea
  crossing different
  varieties of pea plants
  would produce
  characteristic traits of
  both varieties in the
  offspring. He dubbed
  these traits as
  “dominant” and
  “recessive” in
  correspondance to
  their appearance
  frequency.
           THE BASIC IDEA
• Mendel concluded
  from his studies that
  some traits have a
  disposition which
  favors them over
  other traits. These
  traits are Dominant. A
  dominant trait is
  marked by a capital
  letter.
       RECESSIVE TRAITS
• While the dominant traits (marked in grey
  on the previous slide) are more likely to be
  displayed than the recessives, if an
  organism carries 2 recessive alleles (gene
  types) then it cannot display the dominant
  (because it does not carry it). Therefore,
  an organism with this genotype (xx) would
  be considered homozygous recessive.
   HETEROZYGOUS TRAITS and
    INCOMPLETE DOMINANCE
• Organisms carrying a
  dominant and recessive
  allele (Xx) are considered
  heterozygous (one of
  each). An organism in
  this situation usually
  displays the dominant
  allele, except in cases of
  co- or incomplete
  dominance, in which an
  organism displays either
  both traits in competition
  or a compromise between
  the traits.
      Applying Mendel’s Ideas
• Mendelian genetics
  are the precursor to
  modern scientific
  projects such as
  Mapping the Human
  Genome and
  determining
  predisposition to
  disease via family
  history.
    Mendel’s Studies, applied
• Ever wondered if your going to develop a
  disease in your family’s history? Due to
  the research of Mendel, this takes a little
  simple studying (no expensive testing
  necessary, at least initially).
• Ever wonder what color eyes your baby
  will have? Due to the work of Mendel, trait
  mapping is possible when a spouse’s traits
  are known.
          Later life and decline
• First publishing his works
  in a paper titled
  Experiments on Plant
  Hybridization, Mendel
  was ridiculed by the
  scientific community.
  When a reading at the
  Natural History Society of
  Brunn went awry,
  Mendel retired from the
  public eye, tending his
  garden in order to further
  his research on his own.
           Death and Works
• When Mendel died in
  Brno, Austria in 1884
  of a Kidney Infection,
  the monastery burned
  all of his papers, and
  it was not until the
  1900’s that the
  importance of his
  discoveries were
  realized, and he
  became a figure of
  the modern scientific
  circuit.
THE END

				
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