Theory of Evolution There is diversity in living things even within

a species We don't all look alike We don't all behave alike

Those traits can be passed on from parent to offspring

Darwin didn't know how. Mendel did = Genes

There is a struggle to survive Many organism mass produce offspring and few

make it. There is high infant mortality for humans as well in

some places

Theory of Evolution Organisms that are best suited to their environment

have a survival advantage Doesn't necessarily mean the strongest At times it might be good to be small and quiet (early

mammals) Survival of the fittest

Those with a survival advantage will produce more offspring and pass their traits on to those offspring, thus the population will begin to have those particular traits

Natural selection Already known from "unnatural selection" breeding

techniques Large boar with large sow = large piglet.

Fundamental Genetics

In a classic experiment Mendel studied the inheritance of seed color. Dichotomous traits

peas can be brown or white True breeding lines

plants bred to produce only white or only brown peas

Bred white pea plants with a brown pea plants

offspring had all brown peas

Then he bred the offspring with one another 75% brown and 25% white

Implications we do not necessarily inherit the traits of our parents Traits can be passed on across generations

Phenotype Organisms observable traits

Genotype Genetic material that can be passed on

You may have Brown hair and so might your spouse Brown hair phenotype

But it is possible to have a red haired child Red hair Genotype

Mendelian theory

1) There are two kinds of inherited factors for each dichotomous trait For Seed color

A brown seed factor controls brown A white seed factor controls white

Now we call these factors genes

2) Each organism has two genes for each of its dichotomous traits

Each pea plant has either Two brown seed genes Two white seed genes Or one of each

These pairs of genes that control the same trait are called alleles

Homozygous two identical genes for a trait

Heterozygous two different genes for a trait

Dominant vs Recessive Genes

3) One of the two kinds of genes for each trait dominates the other in heterozygous organisms Brown seed is dominant over white

seed if heterozygous it will have brown seeds The only way to have white seeds is to be

homozygous for white seeds

4) Each organism randomly inherits one of it’s father’s two genes and one of it’s mother’s two genes.