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Genetics

Genetics. Why do we look the way we do?. Inheritance of chromosomes. Egg + sperm  zygote. egg. meiosis. zygote. mitosis & development. fertilization. sperm. Inheritance of genes. On the chromosomes passed from Mom & Dad to offspring are genes may be same information

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Genetics

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  1. Genetics Why do we look the way we do?

  2. Inheritance of chromosomes • Egg + sperm  zygote egg meiosis zygote mitosis &development fertilization sperm

  3. Inheritance of genes • On the chromosomes passed from Mom & Dad to offspring are genes • may be same information • may be different information eye color (blue or brown?) eye color (blue or brown?)

  4. Effect of genes • Genes come in different versions • brown vs. blue eyes • brown vs. blonde hair • alleles

  5. Genes affect what you look like X bb BB Bb Bb Bb Bb Where did the blue eyes go??

  6. Genes affect what you look like… X bb Bb Bb Bb bb bb Why did the blue eyes stay??

  7. Genes affect what you look like… X Bb Bb bb BB or Bb BB or Bb BB or Bb Where did the blue eyes come from??

  8. What did we show here? • Genes come in “versions” • brown vs. blue eye color • alleles • Alleles are inherited separately from each parent • brown & blue eye colors are separate & do not blend • either havebrown or blueeyes, not a blend • Some alleles mask others • brown eye color masked blue

  9. eye color (blue?) hair color hair color How does this work? • Paired chromosomes have same kind of genes • but may be different alleles eye color (brown?)

  10. Traits are inherited as separate units • For each trait, an organism inherits 2 copies of a gene, 1 from each parent • a diploid organism inherits 1 set of chromosomes from each parent • diploid = 2 sets of chromosomes 1 from Mom homologous chromosomes 1 from Dad

  11. B B B b b b BB Bb bb Making gametes BB = brown eyes bb= blues eyes Bb= brown eyes  brown is dominant over blue  blue is recessive to brown Remember meiosis!

  12. B B B b b b BB Bb bb How do we say it? 2 of the same Homozygous BB = brown eyes bb= blues eyes homozygous dominant homozygous recessive 2 different Heterozygous Bb= brown eyes

  13. B b B b Punnett squares Bb x Bb male / sperm X BB Bb female / eggs Bb bb

  14. Genetics vs. appearance • There can be a difference between how an organism looks & its genetics • appearance or trait = phenotype • brown eyes vs. blue eyes • genetic makeup = genotype • BB, Bb, bb 2 people can have the same appearance but have different genetics: BB vs Bb

  15. B B B b BB Bb Genetics vs. appearance How were these brown eyes made? eye color (brown) eye color (brown) eye color (brown) eye color (blue) vs.

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