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Dihybrid Crosses

Dihybrid Crosses. Unit 4 – Lecture 6. Dihybrid Cross. a 4x4 representation of crossing TWO traits monohybrid = 1 trait w/ 2 alleles = 1 allele gamete each for 2x2 box dihybrid = 2 traits w/ 2 alleles EACH = 4 alleles = 2 allele gametes each for 4x4 box

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Dihybrid Crosses

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  1. Dihybrid Crosses Unit 4 – Lecture 6

  2. Dihybrid Cross • a 4x4 representation of crossing TWO traits • monohybrid = 1 trait w/ 2 alleles = 1 allele gamete each for 2x2 box • dihybrid = 2 traits w/ 2 alleles EACH = 4 alleles = 2 allele gametes each for 4x4 box [one allele for each trait in each gamete]

  3. Solving a Dihybrid • Determine the genotypes of each parent • Given to you, or you have to solve for them • Given: Parent #1 AABB • Given: Parent #2 aabb

  4. Solving a Dihybrid • Create your dihybrid cross [4x4]

  5. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with first allele of second trait • A A B B • first gamete = AB

  6. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with second allele of second trait • A A B B • second gamete = AB

  7. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with first allele of second trait • A A B B • third gamete = AB

  8. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with second allele of second trait • A A B B • fourth gamete = AB

  9. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with first allele of second trait • a a b b • first gamete = ab

  10. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with second allele of second trait • a a b b • second gamete = ab

  11. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with first allele of second trait • a a b b • third gamete = ab

  12. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with second allele of second trait • a a b b • fourth gamete = ab

  13. Solving a Dihybrid • Label cross w/ parent gametes above / to left

  14. Solving a Dihybrid • Fill in boxes: • fill DOWN each column w/ whatever’s there

  15. Solving a Dihybrid • Fill in boxes: • fill ACROSS each column with whatever’s there

  16. Solving a Dihybrid • Determine Genotype Ratios • record all genotypes you have • count and record number of each genotype • AaBb: 16/16[or 100%]

  17. Solving a Dihybrid • Determine Phenotype Ratios • count how many of each phenotype you have • record # of phenotypes represented • purple, round: 16/16[or 100%]

  18. Solving a Dihybrid #2 • Determine the genotypes of each parent • Given to you, or you have to solve for them • Given – both parents are heterozygous for both traits. • Given: Parent #1 QqRr • Given: Parent #2 QqRr

  19. Solving a Dihybrid • Create your dihybrid cross [4x4]

  20. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with first allele of second trait • Q q R r • first gamete = QR

  21. Solving a Dihybrid • Determine Gametes: • pair first allele of first trait with second allele of second trait • Q q R r • second gamete = Qr

  22. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with first allele of second trait • Q q R r • third gamete = qR

  23. Solving a Dihybrid • Determine Gametes: • pair second allele of first trait with second allele of second trait • Q q R r • fourth gamete = qr

  24. Solving a Dihybrid • Label cross w/ parent gametes above / to left

  25. Solving a Dihybrid • Fill in boxes: • fill DOWN each column w/ whatever’s there

  26. Solving a Dihybrid • Fill in boxes: • fill ACROSS each column with whatever’s there

  27. Solving a Dihybrid • Determine Genotype Ratios • record all genotypes you have • count and record number of each genotype • [not going to make you do it for this one..just know how to]

  28. Solving a Dihybrid • Determine Phenotype Ratios • count how many of each phenotype you have • record # of phenotypes represented • 9/16 - purple, round • 3/16 - purple, wrinkled • 3/16 - white, round • 1/16 - white, wrinkled

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