1. In unicorns, a shiny horn is dominant
In unicorns, a shiny horn is dominant. Cross a female heterozygous, shiny horn, unicorn with a male that has a dull horn. What is the genotypic ratio? Homework: Practice #2 in HP 11 MEIOSIS AND GENETICS TEST FRIDAY

2. Vocabulary Review Genotype- the genetic make-up of an organisms
Phenotype- the physical appearance of an organisms
Homozygous- two of the same alleles
Heterozygous- two different alleles

3. Uses of pedigrees genetic therapy
tracking of a trait through a family tree.

4. Pedigree Best Practices
a pedigree can study only one trait at a time
the trait must be visible
the trait must be controlled by one gene (it cannot be polygenic)

5. Pedigree Symbols

6. Pedigree #1

7. Pedigree #1

8. Pedigree #1

9. Pedigree #1 Characteristics of a dominant pedigree:
1) Every affected individual has at least one affected parent
2) Affected individuals who mate with unaffected individuals have a 50% chance of transmitting the trait to each child; and
3) Two affected individuals may have unaffected children.

10. Pedigree #2

11. Pedigree #2

12. Pedigree #2

13. Pedigree #2 Characteristics of recessive pedigrees:
1) An individual who is affected may have parents who are not affected
2) All the children of two affected individuals are affected
3) In pedigrees involving rare traits, the unaffected parents of an affected individual may be related to each other.

14. Pedigree #3

15. Pedigree #3

16. Pedigree #3

17. Pedigree #3 Characteristics of sex-linked pedigrees
All females from the affected male have the trait, but not all males from affected females (dominant)
All males from the affected female have the trait, but not all females from affected males (recessive)
Males are generally more affected than females