Incomplete Dominance and Codominant Traits

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Incomplete Dominance and Codominant Traits
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Incomplete Dominance (think pink flower)

• The heterozygous offspring genotype has a
  phenotype color that is in-between the parents
  color
• There is no clear dominant trait
• Ratio 121
• Mixture or intermediate color of the parents

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Codominance (think
checkered-chicken)

• Codominance
• 2 dominant alleles are both expressed equally at
  the same time for the same trait

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Sickle-Cell AnemiaA Codominant Trait

• High prevalence in African-Americans that are
  heterozygous for sickle cell
• Sickle cell protects against malaria
• Sickle-cell anemia means people make both regular
  hemoglobin and sickled hemoglobin
• Sickled hemoglobin cannot carry oxygen very well.

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Sickle Celled Hemoglobin vs. Regular Hemoglobin