1. 4.4 Punnett Squares

2. What is a Genotype?

3. Genotype genes that are passed on from parents to offspring.
Showed using Letters
LL, Ll, ll
WW, Ww, ww
RR, Rr, rr

4. What is a Phenotype?

5. Phenotype trait that is seen Think pheno “photo” Examples Blue eyes
Widows peak
Hitch hackers thumb
Curly hair

6. What is an Allele?

7. Allele Different version of the same gene
We usually refer to it as either the dominant allele or the recessive allele
Example
Allele for straight hair (recessive)
Allele for curly hair (dominant)

8. What is a Dominant Allele?

9. Dominant Allele Genotype – Capital Letter (W)
Phenotype – Guaranteed to see it

10. What is a Recessive Allele?
Genotype – Lower case letter (a)
Phenotype – Will not be seen unless both alleles are recessive (aa)

11. What does Homozygous mean?

12. Homozygous
Both Alleles are Alike
Homo = Same
Examples: aa AA WW ww

13. What does Heterozygous mean?
Alleles are opposite
Hetero = different
Examples Hh Aa Ee Gg Yy

14. How to fill in a Punnett Square

15. Review

16. Sample Problem:
Cross a male chicken who is Heterozygous for his blue color with a female chicken who is homozygous recessive black.

17. Cross a male chicken who is Heterozygous for his blue color with a female chicken who is homozygous recessive black.
Genotype Results:
50% Bb
50% bb

18. What does the Phenotype results look like for this punnett square?

19. 2 out of 4 (50%) Blue Chickens 2 out of 4 (50%) Black Chickens