Gregor Mendel (1822-1884)

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Gregor Mendel (1822-1884)

• Austrian monk
• Gardener, scientist, teacher, mathematician
• A truly brilliant man
• Father of genetics

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Mendels experiments

• Studied pea plants and followed the traits passed
  from one generation to the next.
• Cross-pollinated by hand literally thousands of
  plants over many years.
• Closely studied traits such as seed color, seed
  shape, pod shape, pod color, flower color, etc

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When Mendel crossed various pea plants he
discovered interesting, but predictable results,
over and over again.What surprised him the
most, was how a trait could skip a generation,
as if it disappeared, only to reappear in the
next generation.Heres one example (next slide)
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Mendel also noticed that certain traits appeared
to be stronger than others. He called them
dominant. The weaker trait he called recessive.
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Mendels conclusions

• Hereditary traits are passed from parents to
  their offspring during sexual reproduction.
• For each trait, there are two hereditary
  factors - one from the mother and one from the
  father.
• The two inherited factors may be alike (as in
  purebred), or different (as in hybrid).
• When they are different, only one will be
  visible. The visible factor is called dominant.
  The hidden factor is called recessive.

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Modern terminology

• Alleles - what Mendel called factors.
• Different forms of a gene.
• One allele from each parent.
• Might be the same from each parent, or different.
• Genes often occur in pairs of alleles.

• Homozygous - what is often called purebred
  (same alleles from both parents).
• Heterozygous - what is often called hybrid (two
  unlike alleles from each parent).

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Click on the image to watch a short video (315)
on Gregor Mendel.