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Review:

Review:. *Unit factors in pairs - genetic characteristics are controlled by unit factors that exist in pairs in individual organisms *Principle of Dominance and Recessiveness - one factor is dominant over the recessive one

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Review:

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  1. Review: *Unit factors in pairs - genetic characteristics are controlled by unit factors that exist in pairs in individual organisms *Principle of Dominance and Recessiveness- one factor is dominant over the recessive one *Law of Segregation - During gamete formation the paired unit factors segregate randomly so that each gamete receives one or the other

  2. *Law of Independent Assortment – During gamete formation, segregating pairs of unit factors assort independently of each other

  3. Example: P1 X gw yellow, round green, wrinkled gw GGWW ggww gw F1 gw All yellow, round Dihybrid cross- A genetic cross between two individuals involving two characters GW GW GW GW GgWw

  4. F1 F1 X GW All yellow, round All yellow, round Gw GgWw GgWw gW gw 9:3:3:1 Phenotypic ratio; Genotypic ratio as follows: 1/16 GGWW, 2/16 GGWw, 2/16 GgWW, 4/16 GgWw F2 9/16 yellow, round 1/16 GGww, 2/16 Ggww 3/16 yellow, wrinkled 1/16 ggWw, 2/16 ggWw 3/16 green, round 1/16 ggww 1/16 green, wrinkled GW Gw gW gw

  5. Example: Theoretical gene pairs represented by the symbols A, B, and C P1 AABBCC aabbcc X ABC abc Gametes: F1 AaBbCc Gametes: ABC ABc AbC Abc aBC aBc abC abc Trihybrid cross

  6. The Forked-Line Method (branch diagram): Recall: *The F1 that result from a monohybrid cross (AA x aa) all have the genotype Aa and the phenotype represented by A *The F2 that result from a cross between 2 individuals from the F1, have a phenotypic ratio of 3:1

  7. The Forked-Line Method (branch diagram): *NOTE: We are assuming that independent assortment of these 3 gene pairs is a random process!

  8. How do we account for genetic variation? Cross over: *Independent assortment *Crossing over *Random fertilization Independent Assortment:

  9. Chi-Square Analysis: p value (probability): consider as a percentage (i.e. 0.05 = 5%)

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