Gregor Mendel Chapter 10 Gregor Mendel Gregor Mendel

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Gregor Mendel Chapter 10

Gregor Mendel Chapter 10

Gregor Mendel ¡ Gregor Mendel: “Father of Genetics” l Austrian monk l Conducted several

Gregor Mendel ¡ Gregor Mendel: “Father of Genetics” l Austrian monk l Conducted several experiments on pea plants l His work lead to the foundation of modern genetics

Mendel’s Experiments ¡ Cross-Pollination: breeding of 2 different plants (pea plants) l P generation:

Mendel’s Experiments ¡ Cross-Pollination: breeding of 2 different plants (pea plants) l P generation: “parent”; original strains ¡ l F 1 generation: “filial”; offspring of P gen. ¡ l purple x white all appear purple F 2 generation: offspring of self -pollinating F 1 gen. ¡ 3/4 are purple, 1/4 white

Why Peas? ? ? ¡ 1) Peas have distinct characteristics which could easily be

Why Peas? ? ? ¡ 1) Peas have distinct characteristics which could easily be studied l ¡ 2) Mendel could control pea reproduction l ¡ Height, flower color, pea shape, etc. He could cross-pollinate them OR make them self-pollinate 3) Mendel chose true-breeding plants (“homozygous”) l Caused the recessive trait (white flowers) to be “hidden” in F 1 gen. , then reappear in F 2 gen.

Mendel’s Principles ¡ ¡ Principle of Dominance l Some alleles are dominant others are

Mendel’s Principles ¡ ¡ Principle of Dominance l Some alleles are dominant others are recessive Law of Independent Assortment l Each adult has 2 alleles/gene; one from each parent l Alleles for different genes separate independently

Exceptions to Mendel’s Principles ¡ 1) Incomplete Dominance: phenotype is in between those of

Exceptions to Mendel’s Principles ¡ 1) Incomplete Dominance: phenotype is in between those of parents l ¡ i. e. : hazel eyes, wavy hair 2) Codominance: both alleles are expressed in phenotype l i. e. : 2 diff. color eyes, spots in animal fur

Exceptions to Mendel (con’t) ¡ 3) Multiple Alleles: gene has more than 2 alleles

Exceptions to Mendel (con’t) ¡ 3) Multiple Alleles: gene has more than 2 alleles l l l ¡ Results in more possible combinations Individuals still only inherit 2 alleles i. e. : blood type = 3 alleles 4) Polygenic Traits: traits controlled by 2 or more genes l l Leads to wide range of phenotypes i. e. : skin color = 4 + genes