1. Chapter 4 Heredity and Evolution

2. Epigenetics http://video.pbs.org/video/152510747 3/ http://video.pbs.org/video/152510747 3/ LA Times Article

3. Gregor Mendel  A monk living in what is now the Czech Republic  Living in an abbey he crossed different strains of purebred plants and studied their progeny.  His work illustrates the basic rules of inheritance.

4. Traits Mendel Studied in Peas

5. Dominance Dominant traits are governed by an allele that can be expressed in the presence of another, different allele. – Dominant alleles prevent the expression of recessive alleles in heterozygotes.

6. Recessiveness Recessive traits are not expressed in heterozygotes. – For a recessive allele to be expressed, there must be two copies of the allele.