Download Multiple Alleles

TOPIC: Genetics
AIM: How are human
traits inherited?
TOPIC: Genetics
AIM: How do multiple alleles
affect traits?
DO NOW: How many alleles are
required for each trait? Where
do they come from?
The Punnett Squares we learned about are monohybrid
crosses. They involve only 1 trait. A dihybrid cross
involves 2 traits.
EXAMPLE: In guinea pigs,
•B = black fur, b = brown fur
•S = short fur, s = long fur
Multiple • More than 2
Alleles alleles for a trait
• Skin color, blood
type, height…
Blood • A, B, AB, O
Types • A & B genes =
dominant
• O = recessive
• Blood Type A genes =
• Pure = AA
• Hybrid = AO
• Blood Type B genes =
• Pure = BB
• Hybrid = BO
• Blood Type AB genes =
• AB
•Blood Type O genes =
•OO
• 1.
• AB
A
x
B
A AA AB
A AA AB
AA
50% blood type A
50% blood type AB
• 2.
• Cross a person with blood
type AB with someone who
has blood type O.
• AB x OO
• AB x OO
A
B
O AO BO
O AO BO
50% blood type A
50% blood type B
• 3.
• Cross a person who is hybrid
for blood type A with
someone who is hybrid for
blood type B
• AO x BO
• AO x BO
A
O
25% blood type AB
B AB BO
25% blood type B
O AO OO 25% blood type A
25% blood type O
• 4.
• What are the possible blood
types of a child who's parents
are both heterozygous for B
blood type?
• BO x BO
• BO x BO
B
O
B BB BO
O BO OO
75% blood type B
25% blood type O
• 5.
• Cross a female with pure
blood type A and a male with
heterozygous B blood type.
• AA x BO
• AA x BO
B
O
A AB AO
A AB AO
50% blood type AB
50% blood type A
• 6.A male with blood type B has a child with a woman
who has blood type A. The child is blood type O.
What is the genotype of the male and female?
Show your work.
• BO x AO
A
O
A
A
A
A
B AB BO B AB AB
B AB AB
O AO OO B AB AB
O AO AO