1. Mendel’s Second Law: Law of Independent Assortment

2. Bellwork Explain Mendel’s first Law of Inheritance: the Law of Segregation.

3. Objectives Explain the Mendel’s second law of inheritance- the Law of Independent Assortment Explain the relationship between the Law of Independent Assortment and meiosis

4. Key terminology Non-homologous chromosome Dihybrid Cross Independent Assortment of Chromosomes

5. Monohybrid Crosses Involves the transmission of a single trait

6. Next question Mendel Asked: Would the possession of one particular trait (e.g. seed shape) influence the segregation of another trait (e.g. seed color) or would they segregate independently?

7. Dihybrid Crosses Mendel examined simultaneous inheritance of two traits The two traits he examined  Seed shape – Round (R, dominant) versus Wrinkled (r, recessive)  Seed color – Yellow (Y, dominant) versus green (y, recessive)

8. Think-Pair-Share What distinguishes a monohybrid cross from a dihybrid cross? PROPERTY OF PIMA COUNTY JTED, 2010 3

9. Developed two hypotheses Hypothesis 1: Two traits segregate together Hypothesis 2: Two traits segregate independently

10. Hypothesis 1: Two traits segregate together Round (R) always goes with yellow (Y) Wrinkled (r) always goes with green (y) Predicted Results from Punnett Square  3 Round Yellow : 1 wrinkled green

11. Punnett Square of Hypothesis 1

12. Hypothesis 2: Two Traits Segregate Independently Based on this hypothesis there are 4 possible gamete combinations  RY, Ry, rY, ry  Cross RrYy X RrYy  Predicted Results: 9 Round, Yellow: 3 wrinkled, Yellow: 3 Round, green: 1 wrinkled, green

13. Punnett Square of Hypothesis 2

14. Second Law of Inheritance Law of Independent Assortment  Each allele pair on non-homologous chromosomes segregates independently of other gene pairs during gamete formation Why  Because non-homologous chromosomes line up randomly in the center of the cell and pulled to different poles (N vs S) How they assort determines the homologous chromosomes (maternal vs paternal) the gamete possesses

15. Think-Pair-Share Explain the difference between a homologous chromosome pair and a non-homologous chromosome pair. PROPERTY OF PIMA COUNTY JTED, 2010 3

17. 17 3 Minute Paper You have three minutes to write IYOW the Law of Independent Assortment Be prepared to share.