Chapter 4, Heredity and Evolution

1. Chapter 4, Heredity and Evolution • Genetic Principles Discovered by Mendel • Mendelian Inheritance in Humans • Non-Mendelian Patterns of Inheritance • Modern Evolutionary History • Definition of Evolution • Factors that Produce and Redistribute Variation • Review of Genetic and Environmental Factors

2. Mendel’s Discoveries • Segregation • Dominance and Recessiveness • Independent Assortment

3. Principle of Segregation • gamete productionMembers of each gene pair separate so each gamete contains one member of a pair. • fertilizationFull number of chromosomes is restored and members of gene pairs are reunited.

4. Mendelian Inheritance in Humans • Over 4,500 human trains are known to be inherited according to simple Mendelian principles. • The human ABO blood system is an example of a simple Mendelian inheritance.

5. Inherited Genetic Disorders • Dominant disorders are inherited when one copy of a dominant allele is present. • Recessive disorders require the presence of two copies of the recessive allele. • Recessive conditions: cystic fibrosis, Tay-Sachs disease, sickle cell anemia, and albinism.

6. Non-Mendelian Patterns of Inheritance: Polygenic • Polygenic traits are influenced by genes at two or more loci. • Continuous traits have a series of measurable intermediate forms between the two extremes. • Examples: skin color, stature, eye color.

7. Non-Mendelian Patterns of Inheritance: Pleiotropy • A single gene influences more than one phenotype expression. • The rule rather than the exception. • Example: sick-cell anemia, PKU.

8. Modern Evolutionary Theory Evolution is a two-stage process: • Production and distribution of variation. • Natural selection acting on this variation.

9. Factors That Produce and Redistribute Variation • mutation • gene flow • genetic drift • recombination