1. Genetics The scientific study of heredity
Every living thing has a set of characteristics inherited from its parent or parents

2. Chromosomes Located in the nucleus Structure
Tightly coiled (compact)
Contains genetic information

3. Genes and Dominance Trait – specific characteristic
Examples: eye color, blood type
Hybrid – cross between parents with different traits
Genes – small section on a chromosome that determines
a specific trait
Alleles – different forms of a gene
Each gene is composed of 2 alleles (dominant or recessive)

4. Genes and Dominance (cont.)
Dominant gene – prevents other genes from showing their traits
Shown by a capital letter (G)
Recessive gene – does not show its trait when dominant genes are present
Shown by a lower-case letter (g)

5. Gregor Mendel Father of genetics
Crossed true-breeding pea plants and studied the results
He discovered two things:
Law of segregation – each reproducing individual has 2
alleles for each trait
Law of Independent Assortment – the acquisition of 1 trait does not influence the acquisition of another.

6. Principle of Dominance
States that some alleles are dominant and others are recessive
Homozygous – the 2 alleles are identical
Both are either dominant (GG) or recessive (gg)
Heterozygous – the 2 alleles are different
One allele is dominant and one is recessive (Gg)
The dominant trait will always hide the recessive trait

7. Single Crosses
A single cross can be used to predict the trait of an offspring between two individuals
This is done using the Punnet Square Method:
Traits from each parent are shown along the sides
B B
Example: This is a cross between an individual homozygous dominant for brown eyes (BB) and another individual homozygous recessive for blue eyes (bb)
All offspring are heterozygous and have brown eyes Bb b

8. Practice
Cross an individual heterozygous dominant for brown hair (Bb) with an individual recessive for blond hair (bb)