Oregon State University in the Fall 


Oregon State University | College of Science | Biology Program | BI 10X | BI 101 | BI 102 | BI 103

Monohybrid, Dihybrid, and Trihybrid Crosses

Shading in each Punnett Square represents matching phenotypes,
assuming complete dominance and independant assortment of genes,
phenotypic ratios are also presented.

Monohybrid Cross (one gene)
A
a
A
AA
Aa
a
Aa
aa
Phenotypic Ratio
 
3
1

 

Dihybrid Cross (two genes)
AB
Ab
aB
ab
AB
AABB
AABb
AaBB
AaBb
Ab
AABb
AAbb
AaBb
Aabb
aB
AaBB
AaBb
aaBB
aaBb
ab
AaBb
Aabb
aaBb
aabb
Phenotypic Ratio
 
9
3
3
1

 

 

Trihybrid Cross (three genes)
ABD
ABd
AbD
Abd
aBD
aBd
abD
abd
ABD
AABBDD
AABBDd
AABbDD
AABbDd
AaBBDD
AaBBDd
AaBbDD
AaBbDd
ABd
AABBDd
AABBdd
AABbDd
AABbdd
AaBBDd
AaBBdd
AaBbDd
AaBbdd
AbD
AABbDD
AABbDd
AAbbDD
AAbbDd
AaBbDD
AaBbDd
AabbDD
AabbDd
Abd
AABbDd
AABbdd
AAbbDd
AAbbdd
AaBbDd
AaBbdd
AabbDd
Aabbdd
aBD
AaBBDD
AaBBDd
AaBbDD
AaBbDd
aaBBDD
aaBBDd
aaBbDD
aaBbDd
aBd
AaBBDd
AaBBdd
AaBbDd
AaBbdd
aaBBDd
aaBBdd
aaBbDd
aaBbdd
abD
AaBbDD
AaBbDd
AabbDD
AabbDd
aaBbDD
aaBbDd
aabbDD
aabbDd
abd
AaBbDd
AaBbdd
AabbDd
Aabbdd
aaBbDd
aaBbdd
aabbDd
aabbdd
Phenotypic Ratio
 
27
9
9
9
3
3
3
1

 

Oregon State University | College of Science | Biology Program | BI 10X | BI 101 | BI 102 | BI 103