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

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
eye color
hair color

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

5. Genes affect what you look likeX 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 or Bb
BB or Bb
BB or Bb bb
Where did the blue eyes come from??

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

9. 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

10. 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

11. 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

12. 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

13. 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