Why do we look the way we do? Genetics Why do we look the way we do? 2004-2005

Inheritance of chromosomes Egg + sperm  zygote egg meiosis zygote mitosis & development sperm fertilization 2004-2005

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?) 2004-2005

Effect of genes _________________________________ 2004-2005

Genes affect what you look like X Bb Bb BB Bb Bb bb 2004-2005 Where did the blue eyes go??

Genes affect what you look like… X Bb Bb BB Bb Bb bb 2004-2005 Why did the blue eyes stay??

Genes affect what you look like… X Bb Bb BB Bb Bb bb 2004-2005 Where did the blue eyes come from??

What did we show here? Traits come in “versions” brown vs. blue eye color __________________ Traits are inherited as separate units brown & blue eye colors are separate & do not blend brown x blue ≠ brown-blue eyes Some traits mask others brown eye colors masked blue 2004-2005

Paired chromosomes Paired chromosomes have same kind of information  same types of genes eye color (blue?) eye color (brown?) hair color hair color 2004-2005

Traits are inherited as separate units For each trait, an organism inherits 2 copies of a gene, 1 from each parent a ____________ organism inherits 1 set of chromosomes from each parent ____________ = 2 sets of chromosomes 1 from Mom __________________ 1 from Dad 2004-2005

Making gametes Remember meiosis! B BB b BB = brown eyes This all can be expressed using letters flower color = P or p bb b BB = brown eyes bb = blues eyes Bb = brown flower Bb B b Remember meiosis! 2004-2005

How do we say it? B BB 2 of the same ________________ BB = brown eyes bb = blues eyes bb b 2 different ________________ Bb B b Bb = brown flower 2004-2005

Punnett squares _________________ male / sperm female / eggs 2004-2005

Genetics vs. appearance There can be a difference between how an organism looks & its genetics appearance or trait = ___________ brown eyes, blue eyes genetic makeup = ___________ BB, bb, Bb 2 organisms can have the same appearance but have different genetics: BB vs Bb 2004-2005

Genetics vs. appearance How were these brown eyes made? eye color (brown) eye color (brown) eye color (brown) eye color (blue) vs. BB B Bb B b 2004-2005

Woof! Woof! Any Questions? 2005-2006