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Human Genetics Punnett Squares, Incomplete Dominance, Co-Dominance and Dominant/Recessive Traits.

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Presentation on theme: "Human Genetics Punnett Squares, Incomplete Dominance, Co-Dominance and Dominant/Recessive Traits."— Presentation transcript:

1 Human Genetics Punnett Squares, Incomplete Dominance, Co-Dominance and Dominant/Recessive Traits

2 Punnett Squares Named after Reginald PunnettNamed after Reginald Punnett Gregor Mendel-pea plantsGregor Mendel-pea plants Gene combinations/predictionsGene combinations/predictions

3 What to Know Capital letter – dominant traitCapital letter – dominant trait Lowercase letter – recessive traitLowercase letter – recessive trait Homozygous – 2 identical allelesHomozygous – 2 identical alleles Heterozygous – 2 different allelesHeterozygous – 2 different alleles Genotype – genetic makeupGenotype – genetic makeup Phenotype – physical characteristicsPhenotype – physical characteristics

4 Examples T – dominant traitT – dominant trait t – recessive traitt – recessive trait TT- one example of genotypeTT- one example of genotype If T is for tall plants, then Tall is the phenotype for TTIf T is for tall plants, then Tall is the phenotype for TT TT and tt are homozygousTT and tt are homozygous Tt and tT are heterozygousTt and tT are heterozygous

5 Incomplete Dominance BB is a dominant flower color of blueBB is a dominant flower color of blue YY is a dominant flower color of yellowYY is a dominant flower color of yellow The cross results in 100% green flowersThe cross results in 100% green flowers

6 Codominance Both alleles contribute to the phenotypeBoth alleles contribute to the phenotype You will see each trait exhibited separatelyYou will see each trait exhibited separately Many human genes show codominanceMany human genes show codominance Example: chickens with both black and white feathers.Example: chickens with both black and white feathers.

7 More Examples Polygenic traits – skin color, allergies, schizophrenia, cleft lip, and hypertensionPolygenic traits – skin color, allergies, schizophrenia, cleft lip, and hypertension Multiple alleles – human blood, coat color in rabbitsMultiple alleles – human blood, coat color in rabbits

8 Investigate Genetics Web Lab DirectoryGenetics Web Lab DirectoryGenetics Web Lab DirectoryGenetics Web Lab Directory


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