Gregor Mendel

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Gregor Mendel

• The Grandfather of Genetics

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Mendel

• Modern genetics had its beginnings in an abbey
  garden, where a monk named Gregor Mendel
  documented a particulate mechanism of
  inheritance.
• He discovered the basic principles of heredity by
  breeding garden peas in carefully planned
  experiments.
• His approach to science had been influenced at
  the University of Vienna by one of his
  professors the physicist Doppler.

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Mendels work

• In order to study inheritance, Mendel chose to
  use peas, probably as they are available in many
  varieties.
• The use of plants also allowed strict control
  over the mating.
• He chose to study only characters that varied in
  an either-or rather than a more-or-less
  manner.

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Genetic crosses

• To hybridise 2 varieties of pea plants, Mendel
  used an artists brush.
• He transferred pollen from a true breeding white
  flower to the carpel of a true breeding purple
  flower.

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Tracking heritable characteristics

• Mendel tracked heritable characters for 3
  generations.
• When F1 hybrids were allowed to self-pollinate a
  31 ratio of the 2 varieties occurred in the F2
  generation.

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Mendels law of segregation

• By carrying out these monohybrid crosses, Mendel
  determined that the 2 alleles for each character
  segregate during gamete production.
• Mendel discovered this c.1860.
• DNA was not discovered until 1953.

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Mendels terminology

• True breeding When the plants self-pollinate,
  all their offspring are of the same variety.
• Hybridisation Mating, or crossing, of two
  varieties.
• Monohybrid cross A cross that tracks the
  inheritance of a single character.
• P generation True breeding parents.
• F1 generation (first filial) Hybrid offspring of
  the P generation.
• F2 generation (second filial) Offspring from the
  self-fertilisation of the F1 hybrids.

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Mendels impact

• Mendels theories of inheritance, first
  discovered in garden peas, are equally valid for
  figs, flies, fish, birds and human beings.
• Mendels impact endures, not only on genetics,
  but on all of science, as a case study of the
  power of hypothesis/deductive thinking.

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