Transcript Chapter 4 Heredity and Evolution

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
Mendel’s Discoveries



Segregation
Dominance and Recessiveness
Independent Assortment
Principle of Segregation


gamete production
Members of each gene pair separate so each
gamete contains one member of a pair.
fertilization
Full number of chromosomes is restored and
members of gene pairs are reunited.
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.
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, TaySachs disease, sickle cell anemia, and
albinism.
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.
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.
Modern Evolutionary Theory
Evolution is a two-stage process:
1. Production and distribution of variation.
2. Natural selection acting on this variation.
Factors That Produce and
Redistribute Variation




mutation
gene flow
genetic drift
recombination