Slide 1 - bYTEBoss
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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
Genotype
Genetic material that can be passed on
You may have Brown hair and so might your spouse
Organisms observable traits
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
These pairs of genes that control the same trait are called
alleles
Homozygous
Two brown seed genes
Two white seed genes
Or one of each
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.