1. Punnett Squares

2. B stands for Brown Hair b stands for Blond Hair
Capital Letters mean traits are DOMINANT
Lower-Case Letters mean traits are recessive

3. Heterozygous = Having 2 different Alleles (1 dom. + 1 rec.) [Bb]
Homozygous = Having 2 of the same Allele (2 dom. or 2 rec.) [BB] or [bb]

4. If you have…
BB = Brown Hair
Bb = Brown Hair
bb = Blond Hair

5. Dad gives you one AlleleBb
Mom gives you one Allele Bb BB Bb Bb bb

6. Easier Way…

7. Make a window…

8. Dad’s Traits B b B
Mom’s Traits b

9. Dad’s Traits B b B B B
Mom’s Traits b

10. Dad’s Traits B b B B B B b
Mom’s Traits b

11. Dad’s Traits B b B B B B b
Mom’s Traits b B b

12. Dad’s Traits B b B B B B b
Mom’s Traits b B b b b

13. Punnett
Square B b B B B B b b B b b b

14. What % have brown hair?
What % are Homozygous? B B B b B b b b

15. what the trait looks like
Genotype
what the genes are
[“bb” or “Bb”]
Phenotype
what the trait looks like
[long nose or 6 fingers]

16. Things to Know Dominant Allele Recessive Allele Heterozygous
Homozygous (Dom. or Rec.)
Punnett Square
“Carrier” – Bb – Carries recessive gene and can pass it along without showing trait
I’ll make questions using this vocabulary.
I promise.