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Learn about the three types of dominance - complete, incomplete, and co-dominance - and how they manifest in genetic traits. Complete dominance masks recessive alleles, while incomplete dominance results in a blend of traits. Co-dominance involves equal expression of both alleles. Explore examples like flower color in plants and blood types in humans.
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Types of Dominance Pg. 49
1. Complete Dominance-dominant allele completely masks other allele so that it is not expressed. • Only 2 phenotypes possible- the dominant trait and the recessive trait. • Heterozygous organisms have the same phenotype as homozygous dominant organisms.
2. Incomplete Dominance-neither allele is completely dominant over the other, so heterozygous genotypes result in a distinct phenotype different than either homozygous genotype that is usually a blend of the two.3 possible phenotypes RR Rr rr
3. Co-dominance • Both alleles are equally expressed • “Both alleles are dominant” • Homozygous red flower crossed with a homozygous white flower equals heterozygous red AND white flower.
Co-Dominance in Blood Types • ABO system • 4 blood types: • A • B • AB • O