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Chapter 3: Mendelian Genetics. Two main hypotheses on how traits are transmitted: *blending inheritance * particulate inheritance. * Gregor Johann Mendel 1822-1884. Pisum sativum. -Why study (or experiment with) the garden pea?. -Mendel followed several visible features:.
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Chapter 3: Mendelian Genetics Two main hypotheses on how traits are transmitted: *blending inheritance *particulate inheritance *Gregor Johann Mendel 1822-1884 Pisum sativum -Why study (or experiment with) the garden pea? -Mendel followed several visible features:
The Monohybrid Cross -Example: F2 P1 X Tall Dwarf F1 – all Tall
Mendel’s Principles of Inheritance *unit factors 1. Unit factors occur in pairs P1 Tall Dwarf Factors: DD dd Dd
Mendel’s Principles of Inheritance con’t 2. Dominance/Recessiveness P1 X Tall Dwarf DD dd F1 – all Tall Tall Dd
Mendel’s Principles of Inheritance con’t 3. Segregation P1 X Tall Dwarf DD dd F1 – all Tall Tall Dd
Four possible combinations result in F2: DD Dd Dd dd 1 2 3 4 Mendel’s Principles of Inheritance con’t What about the F2? Tall Tall Self cross F1: D d D d
The Test Cross: One Character -How to distinguish DD or Dd genotype? *Test cross
D d D d Punnett Squares Tall Tall Self cross F2: X Dd Dd Gamete formation:
Sample Problem: Albinism in humans is inherited as a simple recessive trait. Determine the genotypes of the parents and offspring for the following families. When two alternative genotypes are possible, list both. (A) Two non albino (normal) parents have five children, four normal and one albino. (B) A normal male and an albino female have six children, all normal.
Mendelian inheritance is based on probability Example- coin toss
Chi-Square Analysis: p value (probability): consider as a percentage (i.e. 0.05 = 5%)