Chapter 14 - Gregor Mendel 1822-1884 Ww ww ww Ww Parental generation(grandparents F1 generation(parents plus aunts and uncles"Experiments in plant

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1 Gregor Mendel 1822-1884 “Experiments in plant hybridization” 1865 pea-plant 2-year experimen Artist: Alois Zenker Gregor Mender, 1884 Abbey of St. Thomas, Brno, Czech Republic experiment plant subjects 20,000 study mostly ignored during the 1800s Ww ww ww Ww Ww ww Ww ww ww Ww F1 generation (parents plus aunts and uncles) Parental generation (grandparents) ♂♀ ♂♀ WW ww or Ww No widow’s peak F2 generation (two sisters) Widow’s peak dominant trait Parental generation (grandparents) Ff Ff FF or Ff ff ff Ff Ff ff ff Ff F1 generation (parents plus aunts and uncles) F2 generation (two sisters) Attached earlobe Free earlobe ff FF or Ff recessive trait Mendel’s laws of inheritance 1860s Segregation (S) Æ alleles of genes separate during gamete formation ( meiosis ), each gamete carries one allele per parent - genes have alternative forms = alleles - S explains 3:1 ratio of F 2 phenotypes in S 2 phenotypes in monohybrid crosses Independent assortment (IA) Æ each pair of alleles segregates into gametes independently of other pairs - IA explains 9:3:3:1 ratio F 2 phenotypes of dihybrid crosses Removed stamens from purple flower Transferred sperm- bearing pol en from stamens of white flower to egg- bearing carpel of purple flower Carpel Stamens Parental generation (P) Pol inated carpel Crossing Pea Plants Mendel crossed purple- and white-color pea plants: If pollen from purple flowers fertilized eggs of matured into pod Planted seeds from pod Examined offspring: al purple flowers First generation offspring (F 1) white flowers Æ F 1 purple flowers same results if white-to- purple fertilizations were conducted P Generation (true-breeding parents) F 1 Generation Purple flowers White flowers F 1 peas crossed with white (hybrids) F 2 Generation All plants had purple flowers F 2 had 3:1 ratio of purple : white phenotypes
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2 purple is dominant over white P > p PP Pp pp homologous pair of chromosomes alleles for purple flowers locus for flower-color gene homologous pair of chromosomes alleles for white flowers P > p P > p P > p Y > y Y > y R > r
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This note was uploaded on 04/16/2008 for the course BIO 131 taught by Professor Paz y mino during the Fall '08 term at UMass Dartmouth.

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Chapter 14 - Gregor Mendel 1822-1884 Ww ww ww Ww Parental generation(grandparents F1 generation(parents plus aunts and uncles"Experiments in plant

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