1 / 17

Dihybrid Crosses

Dihybrid Crosses. **Crossing 2 different traits at the same time. 1. Determine dominant and recessive traits. Carefully read the problem!. 2. Assign letters for the trait. B = black b = white H = Hairy h = no hair. 3. Determine genotype for parents.

dillon
Download Presentation

Dihybrid Crosses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Dihybrid Crosses **Crossing 2 different traits at the same time

  2. 1. Determine dominant and recessive traits Carefully read the problem!

  3. 2. Assign letters for the trait B = black b = white H = Hairy h = no hair

  4. 3. Determine genotype for parents *Parents must have 4 alleles (aka 4 letters) Heterozygous black, hairless male = Bbhh White heterozygous hairy female = bbHh

  5. 4. Draw the punnett square with 16 boxes

  6. 5. Put parent gamete combinations on box Bbhh gametes: Bh, Bh, bh, bh bbHh gametes: bH, bh, bH, bh Bh Bh bh bh bH bh bH bh

  7. 6. Determine the Genotype and Phenotype Ratio Genotype: 4 BbHh : 4 bbHh : 4 Bbhh : 4 bbhh Phenotype: 4 Black and Hair : 4 White and Hair : 4 Black and Hairless : 4 White and Hairless

  8. Sample Problem

  9. Sample Problem Genotype Ratio: ___ RRYY : ___ RRYy : ___ RrYY : ___ RRyy : ___ RrYy : ___ rrYY : ___ Rryy : ___ rrYy : ___ rryy Phenotype Ratio : ___ Round and Yellow : ___ Round and Green : ___ Wrinkled and Yellow : ___ Wrinkled and Green

  10. Sample Problem Genotype Ratio: 1 RRYY : 2 RRYy : 2 RrYY : 1 RRyy : 4 RrYy : 1 rrYY : 2 Rryy : 2 rrYy : 1 rryy Phenotype Ratio : 9 Round and Yellow : 3 Round and Green : 3 Wrinkled and Yellow : 1 Wrinkled and Green

  11. Practice Problem Determine the genotype of the following bunnies: Heterozygous Black-Hairy:_________ White hairless: ____________

  12. Practice Problem Determine the gamete combinations BbHh: _______________________________ bbhh: _______________________________

  13. Practice Problem Complete the punnett square:

  14. Practice Problem Complete the punnett square: BH Bh bH bh bh bh bh bh

  15. Practice Problem Complete the punnett square: BH Bh bH bh bh bh bh bh

  16. Practice Problem Give the genotype ratio: Give the phenotype ratio: 4 BbHh : 4 Bbhh : 4 bbHh : 4 bbhh 4 Black and Hair : 4 Black and Hairless : 4 White and Hair: 4 White and Hairless

  17. Extra tips When determining the probability of events • If the problem states “and” then multiply the chances for each • Chance of heads and heads = ½ x ½ = ¼ or 25% • If the problem states “or” then add the chances for each • Chance of heads or tails = ½ + ½ = 1 or 100%

More Related