Aim: Genetics “Why do we look the way we do? Enter Date Warm-up: HW:

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 eye color hair color

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

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

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

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

What did we show here? Alleles are inherited separately from each parent Some alleles mask others brown eye color masked blue

How does this work? For each trait, an organism inherits 2 copies of a gene, 1 from each parent eye color (blue?) eye color (brown?) hair color

Making gametes B BB BB = brown eyes bb = blues eyes Bb = brown eyes b → brown is dominant over blue → blue is recessive to brown B b Bb

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

b Bb Bb B Bb Bb Punnett squares 100% Brown BB x bb male / sperm B b X Bb Bb 100% Brown Phenotype- Appearance or trait 100% Bb Genetic makeup = genotype BB, Bb, bb female / eggs Bb Bb

B b BB Bb B b Bb bb Punnett squares Bb x Bb 75% Brown 25% blue 25% BB male / sperm B b X BB Bb B b 75% Brown 25% blue female / eggs Bb bb 25% BB 50% Bb 25% bb