1. 5.3 Tracking Inheritance
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2. Pedigree
A diagram of an individual’s ancestors used in human genetics to analyze the Mendelian inheritance of a certain trait; also used for selective breeding of plants and animals.

3. Freckles
The allele for freckles, F, is dominant.

4. Marfan’s Syndrome

5. Pedigree
Example:

6. Legend
Symbols and their meaning:

7. Guidelines:
Roman numerals signify generations Arabic numerals identify individuals within generations. Birth order is left to right

8. Sex Linkage-Following the X and Y chromosome
Autosomal inheritance is found on the autosome Sex-linked genes are found on the X chromosome

9. X-linked
Females must inherit 2 recessive alleles on the X-chromosomes to express the trait. Males only need to inherit one X chromosome from their mothers to express the trait. The Y chromosome cannot mask the trait.

10. hemophilia
Carried on the X chromosome

11. Punnett square for hemophilia
Father is a carrier.

12. Red-green colour blindness

13. X-linked traits The sexes exhibit different phenotypic ratios.
More males than females will express the recessive phenotype.
More females are carriers of the recessive X-linked alleles.
Examples: red-green colour blindness, hemophilia, and male-pattern baldness

14. Y-linked traits
Traits are controlled by a single allele passed on from fathers to sons on the Y chromosome.