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Mendel and Heredity Section 1 The Origin of Genetics
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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
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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
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Pisum sativum Several characters with two forms
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Reproductive traits ◦ Flowers male and female ◦ Can fertilize themselves to produce pea seeds ◦ One plant can fertilize another in cross-pollination too
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Pea plants are: ◦ Small ◦ Easy to grow ◦ Mature quickly ◦ Produce many offspring Results are obtained quickly with plenty of data points
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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
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F 1 Generation BBbb Bb BB b b
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F2F2
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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
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Math lab p165 ◦ Analysis 1-3 Directed and active reading Ch 8 section 1
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