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 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

More than 2 alleles for a trait Skin color, blood type, height… Multiple Alleles

Blood Types A, B, AB, O 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 x AA A B 50% blood type A A A A A B 50% blood type AB A A A A B

2. Cross a person with blood type AB with someone who has blood type O. AB x OO

AB x OO A B 50% blood type A O A O B O 50% blood type B O A O B O

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 25% blood type AB 25% blood type B 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 B B B O 75% blood type B O B O O O 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 A B A O 50% blood type AB A A B A O 50% blood type A

BO x AO A O A A A A B A B B O B A B A B B A B A B O O A O O O B A O 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 A B B O B A B A B B A B A B O O A O O O B A O A O A B A B