Allele Combinations

# Allele Combinations

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## Allele Combinations

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1. Allele Combinations • Each parent must give 1 allele for each gene • So a parent can give AB or ab etc. • A parent cannot give AA or Bb. • EASY way to figure out allele combinations one parent can give is FOIL. • First • Outer • Inner • Last • FOIL the following- AaBb

2. FOIL-Heterozygous Dihybrid (AaBb x AaBb) The First= AaBb = AB The Outer= AaBb = Ab The Inner= AaBb = aB The Last = AaBb = ab • The other parent would be the same because it is also a heterozygous dihybrid! • Follow alphabetical order THEN upper case

3. Dihybrid grid • Set up your grid and fill in the blanks as we did in monohybrid crosses. List the total number of Genotype & Phenotypes Let’s assume A = Widows peak a = no widows peak B= cleft chin b= no cleft chin

4. Genotype/Phenotype predictions • Phenotype: • Widow/ • cleft = 9 • Widow/ • No cleft = 3 • No Widow/ Cleft = 3 • No widow/ • no cleft = 1 • Genotype: • AABB = 1 • AABb = 2 • AaBB = 2 • AaBb = 4 • AAbb=1 • Aabb = 2 • aaBb = 2 • aaBB = 1 • aabb = 1 AAbb