1. Dihybrid Cross

2. Some practice with gentotypes:
Dihybrid cross – cross (mating) between parents that differ by 2 traits
Some practice with gentotypes:
(round dom. to wrinkled, yellow dom. to green)
RrYY _______________ rrYy __________________
rryy ________________ Rryy __________________

3. Mendel’s 1st Dihybrid Cross
P round yellow seeds x wrinkled green seeds (RRYY) (rryy) ↓ cross-pollinate F1 all round yellow seeds ↓ self-pollinate F2 9 round yellow:3 round green: 3 wrinkled yellow:1 wrinkled green

4. Law of Independent Assortment – genes found on different chromosomes are inherited independently of each other
Ex. RrYy can make the following gametes:

5. WRONG WAY! Steps to solving dihybrid crosses:
Make gametes for each parent.
Put gametes of one parent on top of square and the other parent on the side of square.
Fill in squares.
Determine ratio of offspring.
Example: RrYy x RrYy
R r Y y R r Y y
WRONG WAY!