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The Monk who loved peas

The Monk who loved peas. How to Make a Living Thing. Gregor Mendel. Monk, failed teacher, pea-lover, genetic genius From growing peas, Mendel noticed that offspring did not always have the same traits as the parents

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The Monk who loved peas

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  1. The Monk who loved peas How to Make a Living Thing

  2. Gregor Mendel • Monk, failed teacher, pea-lover, genetic genius • From growing peas, Mendel noticed that offspring did not always have the same traits as the parents • But then the parent’s trait would show up again in a “grandchild,” or 2nd generation • So Mendel began to experiment, attempting to grow peas with certain traits, or characteristics

  3. The Proof is in the Peas • Peas were an excellent choice for his research for two reasons • They can self-pollinate, creating offspring with the same traits as the parent • Or, they can cross-pollinate with other peas

  4. The Experiment • Mendel looked at one characteristic at a time (color, height, shape) • If a pea plant has a white flower, then it self-pollinates, you’ll have offspring with white flowers • What happens if a purple-flowered pea plant cross-pollinates a white-flowered pea plant?

  5. Mendel’s Discovery • Mendel noticed the offspring of a purple-flowered pea plant and a white one was always purple • BUT, the “grandchildren” or 2nd generation, would have 1 white-flowered pea plant for every three purple ones

  6. Dominant Traits • Dominant traits are the ones always showing up in the first generation • The purple-flowered pea plant • In a Punnett Square, dominant traits are symbolized by a capital letter

  7. R r R RR Rr r Rr rr Recessive Traits • “Fade into the back” • The white-flowered pea plant • These traits reappear in the 2nd generation • MUST be paired with another recessive allele

  8. Incomplete Dominance • Sometimes, one trait is NOT dominant over the other • Each allele provides some influence • Hair texture—curly, straight, and wavy—is an example in humans

  9. Genes • The instructions for one particular trait are called a gene • You have 2 forms of the same gene for every characteristic • 1 from Mom, 1 from Dad • Hair color, eye color, height, hitchhiker’s thumb, etc.

  10. Alleles • The form of a trait given by one parent • So, for each gene, you have 2 alleles • Either dominant (capital letter) or recessive (lower-case)

  11. Genotype and Phenotype ·Both inherited traits form a genotype --Aa; rr; etc. ·The appearance of a characteristic is the organism’s phenotype --a purple flower; wrinkled peas; wavy hair

  12. Genetic Probability and Pedigrees • Probability is the mathematical chance of an outcome • Aa x Aa has a 25% chance of getting aa as an outcome; 25% AA; 50% Aa • Pedigrees are like family trees for determining the probability of genetic diseases like cystic fibrosis

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