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Unformatted text preview: 1 26-Sep-09 Gardiner 1 Gregor Mendel Fig. 12-2, p. 236 B I O L O G Y 0 2 3 26-Sep-09 Gardiner 2 Heredity Historical Perspective For much of human history people were unaware of how heredity worked Greek philosophers male flowers caused female flowers to open seeds produced by various body parts and transmitted to offspring at time of conception During 1700s Anton van Leeuwenhoek saw animalcules in sperm of humans and animals Some scientists speculated they saw little man in each sperm Pangenesis males and females formed pangenes in every organ These pangenes then moved through their blood to the genitals and then to children Concept originated with Greeks and influenced biology up to around 100 years ago The terms blood relative, full-blooded and royal blood Francis Galton (Darwins cousin) disproved the theory in the 1870s B I O L O G Y 0 2 3 26-Sep-09 Gardiner 4 Gregor Mendel Grew up on a farm in what is now Czech Republic (Austria) 1843 entered monastery University of Vienna Became a teacher Interest in breeding plants at monastery B I O L O G Y 0 2 3 26-Sep-09 Gardiner 5 Why peas ? Mendel also worked with other species -Peas worked better -Peas had 7 traits that gave results Mendel could understand -Other traits he could not Rule # 1 of good science Work with things that work! Mendels 7 Pairs of Contrasting Pea Traits As in Fig. 11.4 2 Mendels Methods Emasculation Cross-pollination Careful observation of progeny Statistical interpretation of the results Like Fig. 11.3 In a typical breeding experiment, Mendel would cross-pollinate ( hybridize ) two contrasting, true-breeding pea varieties. The true-breeding parents are the P generation and their hybrid offspring are the F 1 generation . Mendel would then allow the F 1 hybrids to self-pollinate to produce an F 2 generation. It was mainly Mendels quantitative analysis of F 2 plants that revealed the two fundamental principles of heredity: the law of segregation and the law of independent assortment. B I O L O G Y 0 2 3 26-Sep-09 Gardiner 9 Terms Character a heritable feature Trait a variant of a character True-breeding organisms which when they breed produce the same characters Hybridization mating or crossing of two varieties Monohybrid cross...
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This note was uploaded on 04/18/2010 for the course BIOLOGY 1223 taught by Professor Gardiner/lajoie during the Spring '09 term at UWO.
- Spring '09