1. Coulter

2. Patterns of human inheritance Some human traits are controlled by single genes with two alleles, and others by single genes with multiple alleles. Still other traits are controlled by many genes that act together.

3. Single genes with two alleles Many human traits are controlled by a single dominant allele and one recessive allele. These traits have to different phenotypes.

4. Single genes with multiple alleles Multiple alleles: three or more forms of a gene that code for a single trait. Even though a gene may have multiple alleles a person can only carry two alleles. Chromosomes exist in pairs.

5. Single genes with multiple alleles Blood type is controlled by multiple alleles. Three alleles control the inheritance of blood types. Alleles for blood type A (IA) and B (IB) are co- dominant. Blood type O (i) is recessive. What does it mean if a person inherits A from one parent and B from the other in this co-dominant situation?

6. The sex chromosomes The sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits. If you are a girl you are XX If you are a boy you are XY Why does everybody have one X?

7. Sex-linked genes Sex-linked gene are traits passes from a parent to a child on a sex chromosome. Red/green Colorblindness Most genes on the X chromosome are not on the Y chromosome. This means that an allele on the X chromosome may have no corresponding alleles on the Y chromosome. This means males are more likely to have a sex linked gene than females.

8. Inheritance of colorblindness Colorblindness is controlled by a recessive allele on the X chromosome. Punnett square female is a carrier (hybrid) Daughters are not colorblind they are carriers.

9. The effect of environment Many of a person’s characteristics are determined by an interaction between genes and the environment. Height can be affected by diet.

10. Sex linked genes