Patterns of Heredity Incomplete Dominance, Codominance and Sex-linked.
Incomplete and Codominance - teachers.sduhsd.netteachers.sduhsd.net/kstapko/Biology/Unit 6- Preview...
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Transcript of Incomplete and Codominance - teachers.sduhsd.netteachers.sduhsd.net/kstapko/Biology/Unit 6- Preview...
Review: Complete/Classic Dominance
When dominant alleles overpower the recessive allele.One dominant is all that is needed for an individual to show the dominant phenotype.
Incomplete DominanceWhen two or more alleles influence the phenotype.No allele is completely dominant, therefore, heterozygous individuals will show an intermediate (or third) phenotype.
Codominance
Both alleles are equally dominant.Both alleles are therefore expressed equally in the phenotype of heterozygous individuals.
RR
Red Coat Color
Practice Problems
Assuming incomplete dominance... If: R = Red and r = blueWhat phenotypes would you see
with:–RR=–rr =–Rr =
Assuming incomplete dominance... If: R = Red and r = blueWhat phenotypes would you see
with:–RR= Red– rr = Blue–Rr = Purple
Practice Problem
Assuming codominance... If: R = Red and r = blueWhat phenotypes would you see
with:–RR=–rr =–Rr =
Assuming codominance... If: R = Red and r = blueWhat phenotypes would you see
with:–RR= Red– rr = Blue–Rr = Red and Blue (Spots, Stripes, etc)
Dominance Combinations
Sometimes certain alleles are completely dominant and others are not.This is the case with blood types
Blood Types
Blood Type alleles–A: Completely dominant to o; codominant with B
–B: Completely dominante to o; codominant with A
–o: Completely recessive
Blood Types
Genotype
AA
Ao
BB
Bo
AB
oo
Phenotype
A blood type
A blood type
B blood type
B blood type
AB blood type
O blood type