170 likes | 186 Views
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.
E N D
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