Download Punette Squares

Punnett Squares
• Developed by an English Biologist,
Reginald Punnett in 1905.
• A method to predict the possible _______
of the ________ if the genotypes of the
parents are given.
1
_________ Cross= crossing one trait
Suppose both your parents have
brown eyes and you also have brown
eyes. Yet, your sibling has blue eyes.
Would your sibling be an adopted
sibling or your full-blooded sibling?
How would you explain this?
2
If your parents have dominant genes…
B = brown eye (dominant)
b = blue eye (recessive)
BB x BB
(homozygous dominant)
Brown = _______%
Blue = _______%
3
If your parents have dominant and
recessive genes…
B = brown eye (dominant)
b = blue eye (recessive)
Bb x Bb (heterozygous)
Brown = _______%
Blue = _______%
4
If one parent is homozygous
dominant and the other parent is
heterozygous…
BB (homozygous dominant)
x Bb (homozygous
recessive)
Brown = _______%
Blue = _______%
5
Punnett Squares: Blood Type
• A, B = dominant
• O = recessive
Father is type A,
homozygous; mother is
type B, homozygous
O = ______ %
A = ______ %
B = ______ %
AB = ______ %
6
Punnett Squares: Blood Type
• A, B = dominant
• O = recessive
Father is type A,
heterozygous; mother is
type B, heterozygous
O = ______ %
A = ______ %
B = ______ %
AB = ______ %
7
Punnett Squares: Blood Type
• A, B = dominant
• O = recessive
Father is type O; mother is
type AB
O = ______ %
A = ______ %
B = ______ %
AB = ______ %
8
Punnett Squares: Blood Type
• A, B = dominant
• O = recessive
Father and mother are
both type AB
O = ______ %
A = ______ %
B = ______ %
AB = ______ %
9
_________ Cross
• Crossing two traits
• Involves two different alphabet letters. (ex.
A and B)
• Different alphabet letters represent
different _____. Two letters for each trait.
• So, altogether, ____ letters for two traits
per individual. AaBb
10
Dihybrid Cross
• How many possible combinations of _______
can you make?
AaBb (heterozygous for both traits)
- 4 different letter combos or gametes
- AB, Ab, aB, ab
AABb (homozygous & heterozygous)
- 2 different letter combos or gametes
- AB, Ab
11
Dihybrid Cross
E = brown eye
e = blue eye
H = Brown hair
h = blonde hair
EeHh x EeHh
12
Dihybrid Cross
E = brown eye
e = blue eye
H = Brown hair
h = blonde hair
EeHH x EEHh
13