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3.3 Patterns of Inheritance

3.3 Patterns of Inheritance. Pgs. 50-54. 3.3 Patterns of Inheritance. Traits: desirable characteristics in organisms. We will uses animal fur color to focus on patterns of inheritance in this section .

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3.3 Patterns of Inheritance

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  1. 3.3 Patterns of Inheritance Pgs. 50-54

  2. 3.3 Patterns of Inheritance • Traits:desirable characteristics in organisms. We will uses animal fur color to focus on patterns of inheritance in this section. • Purebred:organisms whose ancestors have only produced one trait(white fur offspring) for several generations(either BB or bb, uppercase uppercase or lowercase lowercase) • Hybrid:an individual produced by crossing two purebred parents that differ in a trait (such as fur color) (always Bb, uppercase and lowercase)

  3. Patterns of Inheritance F E M A L E (bb) MALE (BB)

  4. Dominant Traits – the one that you see • If we cross a purebred white female (bb)with a purebred black male (BB), we notice the result is that all offspring have the same black coat (Bb). • A trait expressed preferentially over another trait. F E M A L E M A L E • Black fur is dominant because all offspring have black coats.

  5. Recessive Traits – “a carrier” F E M A L E • The opposite of dominant. A trait that is preferentially masked. • Has the white coat allele in the hybrid offspring disappeared? • No, to find out, we need to cross the hybrid female offspring with the hybrid male offspring. • The result is that¾of theoffspring are black, and¼is white. M A L E • The white fur kitten is and example of a recessive trait.

  6. How to know what color, or what trait will show… • If it is a purebred, then it will have the trait of the purebred. • BB – black cat. • bb – white cat • If it is a hybrid, it will always show the dominant trait. • Bb - black • Question: If we are talking about eye color, and I tell you brown eyes(E) are dominant over blue (e) what eye color will the following people have? • EE - Ee - ee-

  7. Homozygous vs. heterozygous • If the organism has two of the same alleles, (BB or bb) it is considered homozygous! • If the organism has different alleles, (Bb) it is considered heterozygous!

  8. Genotype vs. phenotype • Genotype is the genetic information. (BB, Bb, bb). • Genotype = genes! • Phenotype is what it will look like. (black, white) • Phenotype = looks!

  9. Incomplete Dominance • Sometimes the dominant-recessive pattern does not always work. • When a purebred black cat and a purebred white cat are crossed its offspring can be grey. • Neither of the parents’ alleles are dominant or recessive.

  10. Punnett square • An easy method to figure out what the off spring will look like!

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