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Chapter 26: Genetics

Chapter 26: Genetics. Genes and chromosomes. Eye color. Hair color. Skin color. Nose size. Nose shape. Genes. Eye shape. hair texture. Ear size. widow’s peak. Ear lobes. Chromosome. Types of Chromosomes. Sex Cell. Body Cell. Chromosomes NOT paired.

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Chapter 26: Genetics

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  1. Chapter 26: Genetics

  2. Genes and chromosomes Eye color Hair color Skin color Nose size Nose shape Genes Eye shape hair texture Ear size widow’s peak Ear lobes Chromosome

  3. Types of Chromosomes. Sex Cell Body Cell Chromosomes NOT paired Chromosomes are paired and therefore have two genes for every trait

  4. A body cell has ___________ genes for every trait. two One Sex cells only have ________ gene for every trait

  5. egg sperm Fertilized egg

  6. B = Brown eyed Dad b = Blue eyed Mom b B Child has a gene for BLUE eyes and a gene for BROWN eyes… ???? B b

  7. What happens when you have a gene for Brown eyes AND a gene for Blue eyes?? A gene that will SHOW the trait Dominant B B = ___________________ B b = ___________________ Brown eyes Brown eyes A gene that will NOT show the trait if a dominant gene is present. Recessive b b = Blue eyes

  8. Terminology: GENOTYPE – a person’s genesPHENOTYPE (physical appearance) B B Brown eyes = HOMOZYGOUS Dominant (pure dominant) B b = HETEROZYGOUS (hybrid) Brown eyes b b = HOMOZYGOUS recessive (pure recessive) Blue eyes

  9. Possible Sperm Possible Eggs B B b b What are the possible outcomes for the child?

  10. Dad is B b Mom is B b Possible Sperm Possible Eggs B B = brown eyes B B B b = brown eyes b B b = brown eyes b b b = blue eyes

  11. Punnett Square A method for predicting the possible outcomes (offspring) of a genetic cross Mother’s Genes B b B B B B b Father’s Genes B b b b b

  12. Sperm Sperm offspring egg offspring egg offspring offspring

  13. B B b B b B b b B b B b B B b b X B b B b B b B b

  14. B b b B b b b b B b b b B b b b X B b B b b b b b

  15. B b B B B B b b B b b b B b B b X B B B b B b b b

  16. Gregor Mendel: 1865 • Austrian monk • Father of genetics • Botanist • Worked with pea plants. • Discovered recessive and dominant genes using mathematics • Genetics – study of how traits are passed from parent to offspring

  17. Mendel’s experiments: GG gg G G Gg Gg g P1 All yellow * green trait “disappeared”?? Gg Gg g F1 G g G GG Gg 3 yellow 1 green Gg gg g F2 yellow Yellow yellow green *green trait “re-appeared”

  18. Mendel repeated this for all the traits of a pea plant. Since the results were the same, he concluded: TT x TT = all tall TT x Tt = all tall TT x tt = all tall Tt x Tt = ¾ tall, ¼ short Tt x tt = ½ tall, ½ short tt x tt = all short Mendel used statistics and punnett squares to accurately predict the outcomes of all his possible genetic crosses.

  19. Proving Mendel’s work T T T T T T T t T T T T T T T T T T t T t T T T T T T t T t T t t T t t 4 tall 4 tall 4 tall T t T t t t T t T t T T T T t t t t t t t T t t t t t t t t t t t t t t 3 tall, 1 short All short 2 tall, 2 short

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