*Gregor Johann Mendel Chapter 3: Mendelian Genetics Two main hypotheses on how traits are transmitted: *blending inheritance *particulate inheritance Pisum sativum -Why study (or experiment with) the garden pea? -Mendel followed several visible features:

The Monohybrid Cross -Example: X TallDwarf P1P1 F 1 – all Tall F2F2

Mendel’s Principles of Inheritance *unit factors 1. Unit factors occur in pairs TallDwarf P1P1 Factors: DD dd Dd

2. Dominance/Recessiveness Mendel’s Principles of Inheritance con’t X TallDwarf P1P1 DD dd F 1 – all Tall Tall Dd

Mendel’s Principles of Inheritance con’t 3. Segregation DD dd X TallDwarf P1P1 F 1 – all Tall Tall Dd

DdDd Tall Mendel’s Principles of Inheritance con’t What about the F 2 ? Self cross F 1 : dDDdDdDdDd Four possible combinations result in F 2 : 1234

The Test Cross: One Character -How to distinguish DD or Dd genotype? *Test cross

Punnett Squares DDd Tall Self cross F 2 : Dd X Gamete formation: d

CH3 Problem #2: 2. 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

The Rule of Addition

Chi-Square Analysis: p value (probability): consider as a percentage (i.e = 5%) Example from Table 3.1: