Mendel and Heredity Section 1 The Origin of Genetics

 The passing of traits from one generation to another ◦ People have been working with this for centuries  Ex: Selective breeding for traits in dogs or farm animals ◦ They knew it happened but not what caused it  Gregor Mendel is considered the “father” of genetics ◦ Austrian monk ◦ Studied pea plants ◦ Predicted outcome of crosses

 First to use quantitative analysis (statistics)  Retried T.A. Knight’s experiments with peas ◦ This time he kept track of both the types of offspring and their numbers

 Pisum sativum  Several characters with two forms

 Reproductive traits ◦ Flowers male and female ◦ Can fertilize themselves to produce pea seeds ◦ One plant can fertilize another in cross-pollination too

 Pea plants are: ◦ Small ◦ Easy to grow ◦ Mature quickly ◦ Produce many offspring  Results are obtained quickly with plenty of data points

 Began with a monohybrid cross ◦ Involves one pair of contrasting traits  Purple and White flowers is the classic example 1.Begin with true breeding white and purple flowered plants 2.Cross-fertilize the two making the F 1 generation (first filial)  Grow the seeds, observe and record the flower color 3.Allow the F 1 plants to self fertilize making F 2  Grow the seeds, observe and record flower color

F 1 Generation BBbb Bb BB b b

F2F2

 No matter the trait the F2 turned out in a 3:1 ratio ◦ Not exact but always close ◦ Too consistent to be chance ◦ Must be some sort of system to heredity  Mendel set out to determine the rules of heredity

 Math lab p165 ◦ Analysis 1-3  Directed and active reading Ch 8 section 1