Dihybrid Crosses -A dihybrid cross is a way to predict the genotype and phenotype of an offspring -The dihybrid cross is a probability, not an absolute certainty -A dihybrid cross analyzes the probability of two genes together on a chromosome (ie. Color AND size, shape AND position, etc)

Dihybrid Crosses -A dihybrid cross is solved in a similar manner as the monohybrid cross, although it is more complex -With two traits being studied at one time, genotypes must be appropriately organized ex. BbSs crossed with BbSs To organize the alleles each parent can give, distribute each allele of one gene with all the other alleles of the other gene as below:

Dihybrid Crosses -When you do this, you ultimately get 4 different allele combinations: BS, Bs, bS, and bs (for one parent) -Once you have the allele combinations for both parents, you can enter it into a dihybrid Punnett Square where you would distribute the alleles as you would in a monohybrid Punnett Square -Possible parental alleles go on the left and the top, and the alleles are then placed in the appropriate box

Dihybrid Crosses -Probabilities are based out of 16: 1/16 BBSS 2/16 BbSS 1/16 bbSS 2/16 BBSs 4/16 BbSs 2/16 bbSs 1/16 BBss 2/16 Bbss 1/16 bbss

Dihybrid Crosses Directions: Determine the possible alleles that each parent below can give to their offspring: 1. TtDd 2. TTdd 3. ttDd 4. Ttdd 5. TtDD 6. TTDD 7. ttdd 8. TTDd 9. ttDD Answers: 1. TD Td tD td 2. Td Td Td Td 3. tD td tD td 4. Td Td td td 5. TD TD tD tD 6. TD TD TD TD 7. td td td td 8. TD Td TD Td 9. tD tD tD tD