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Genetics 2

Genetics 2. Law of Segregation- The random Assortment of either pair of homologous chromosomes to opposite poles during Meiosis I. Creates different gametes.

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Genetics 2

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  1. Genetics 2

  2. Law of Segregation-The random Assortment of either pair of homologous chromosomes to opposite poles during Meiosis I. Creates different gametes.

  3. Law of Independent Assortment-The movement of one pair of chromosomes odes not affect the movement of another pair. They segregate independently.

  4. Gregor Mendel’s Crosses Gregor Mendel was an Augustinian Monk. Studied under Physicist Doppler and Botanist Unger. In 1857 began breeding and cross breeding pea plants. Results yielded two previous laws. Nothing was known about genes or DNA.

  5. Gregor Mendel’s Crosses Mendel experimented with different varieties of pea plants. Observed and counted offspring. Ex. Purple flowered plant x White flowered plant.

  6. Gregor Mendel’s Crosses P = Parental Generation Purple x White F1= First Filial Generation All purple F2 = Second Filial Generation 3:1 Purple to white What is dominant? How do we explain?

  7. Monohybrid Cross Cross a Homozygous Dominant Purple (PP) flowered plant with a Homozygous recessive White flowered plant(pp) A mating in which just 1 trait is focused on. Ex. Just plant color or just plant height. Letters are used to represent the parent’s genes. P P p Pp Pp p Pp Pp

  8. Monohybrid Cross The offspring have one gene from each parent but only show purple phenotype. Now cross the offspring. P p P PP Pp p Pp pp Heterozygous Purple Flower x Heterozygous Purple Flower

  9. Monohybrid Cross The offspring show a 3 : 1 phenotype distribution. 1 PP Homo. Dom. Purple 2 Pp Hetero. Purple 1 pp Homo. Rec. White Genotype Phenotype P p P PP Pp p Pp pp

  10. Test Cross Used to determine a genotype that is unknown. Ex. A purple flower of unknown genptype with a white pp flower. Predict outcome for each scenario and compare with actual results.

  11. Dihybrid Cross A mating in which 2 different traits are focused on at the same time. Ex. Both plant color & height (more complex) PT PT PT PT pt PpTt pt pt pt Homo. Dom. Purple Tall x Homo. Rec. White Short 16 PpTt purple tall plants

  12. Dihybrid Cross Now try the cross between the offspring. A heterozygous purple tall plant with a heterozygous purple tall plant. PT Pt pT pt PT PPTT Pt pT pt 9 Purple Tall 3 Purple Short 3 White Tall 1 White Short

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