1. Learning Objectives How to Read Pedigree diagrams properly
How to Draw Pedigree diagrams
How to use Pedigree diagrams to make conclusions about past and future genotypes
How to recognize sex-linked traits in PD diagrams
How to draw sex-linked traits in PD diagrams

2. F1: Parental (1st) generation
Pedigree Diagrams: Tracing traits through a family’s history
= boys
= girls
Reproductive mating
F1: Parental (1st) generation
F2: 2nd generation
Time Proceeds Downwards

3. Pedigree Diagrams: Tracing traits through a family’s history = boys
= girls
Trait: Hair Color
B-Brown hair (dominant)
b-blonde hair (recessive)
(Brown) BB or Bb = or
(Blonde) bb = or F1 F2 F3
Brown
hair
Blonde

4. Pedigree Diagrams: Often can use the phenotype to help determine a family’s genotype for traitsBb bb BB B? Bb Bb

5. Now lets really test your skills

6. Simpson's Pedigree: Non-Sex linked Trait of Hair Color
Yellow ( & brown) Hair – Y – Dominant
Blue hair – y- Recessive F1 yy Y? yy Yy F2 Yy yy yy F3 Yy

7. X Y
Sperm
Sex Chromosomes X
Egg XX XY
Notice: equal chance of having a boy or girl, and father still determines the gender of the child (only the male can give the Y chromosome)

8. Autosomes
Sex
Chromosomes

9. Sex-Linked Genes: Genes that are inherited on either the X or Y chromosome (sex chromosomes)
Ex: Eye color in Fruit Flies
R – red eyes (dominant)
r – white eyes (recessive)
XR or Xr Y
No eye color gene on the Y chromosome
So the X chromosome becomes even more important

10. XR or Xr or Y XR XR 33.3% XR Xr Xr Xr XR Y 50% Xr Y
R – red eyes r – white eyes
XR or Xr or Y
Odds of white eyes
Genotype
Phenotype
Sex
XR XR
XR Xr
Xr Xr
XR Y
Xr Y
Red Eyes
White Eyes
Female
Male
33.3%
50%

11. -For recessive sex-linked Traits: -Girls can be carriers (XEXe)
Red-green Color Blindness is a recessive sex-linked Trait:
XE and Xe Y
E –normal eye color vision gene
e – red-green color blind gene
Has no color gene
XE XE XE Xe Xe Xe XE Y Xe Y
Normal Carrier C.B Normal C.B.
Vision Vision
1/3
1/2
-For recessive sex-linked Traits:
-Girls can be carriers (XEXe)
-Boys are more often fully affected than girls

13. 74

14. 60

15. 29 25 56 45 8
???

16. ? XE Y XE Xe Xe Y XE X? -For recessive sex-linked Traits:
-Girls can be carriers (XEXe)
-Boys are more often fully affected than girls
XE Y
XE Xe ?
Xe Y
XE X?

17. XE Xe XE Y F1 F2 F3 -For recessive sex-linked Traits:
-Girls can be carriers (XEXe)
-Boys are more often fully affected than girls F1 F2 F3
XE Y
XE Xe
Xe Y
XE Xe
XE XE
XE Y
XE Y
XE Xe

18. XE Xe XE Y F1 F2 F3 -For recessive sex-linked Traits:
-Girls can be carriers (XEXe)
-Boys are more often fully affected than girls F1 F2 F3
XE Y
XE Xe ?
Xe Y
XE X?
XE XE
XE Y ?
XE Y
XE X?
XE Xe

19. -For recessive sex-linked Traits: -Girls can be carriers
-Boys are more often fully affected than girls
Sex-linked, recessive trait.

20. Sex Linked Trait or not?
Not Sex-linked Trait (Autosomal)

21. Sex Linked Trait or not?
Sex Linked (recessive )Trait