1. Introduction to Genetics
Chapter 11
Introduction to Genetics

2. Golden Doodle Blending Theory offspring are a straight mix
A Brief History
In the past, people did not understand how traits were inherited, but there were many guesses based on things that could be observed.
Two theories emerged….
Blending Theory
offspring are a straight mix
Particulate Theory
traits are inherited as "particles", offspring receive a "piece" from each parent, some pieces may hide the others
Golden Doodle

3. Who was Gregor Mendel? GENETICS study of heredity HEREDITY
He was known as the “FATHER OF GENETICS”
He discovered how traits were inherited.
GENETICS
study of heredity
HEREDITY
the passing of traits from parents to offspring

4. Mendel’s Peas Mendel did his study on pea plants
which have many traits:
- tall/short
- purple/white flowers
- round/wrinkled seed

5. Mendel’s Experiments Example
Mendel conducted self-pollination and cross pollination to observe expression of pea plant traits.
Example

6. Mendel’s Pea Plant Experiment
P1 Generation
F1 Generation
F2 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short
Cross Pollination
Self Pollination
Final Results

7. Mendel’s Results
F1 plants = 100% tall
F2 plants = 75% tall, 25% short
Similar results occurred when each trait of a pea plant was isolated.
Ex. Yellow/green seeds
smooth/wrinkled seeds

8. Mendel’s Conclusions
Traits are passed on by genes from parent to offspring.
Principle of Dominance & Recessiveness
- one trait may hide the expression of another trait.
- Dominant- trait that is always expressed if
present.
- Recessive- trait that is hidden if a dominant
trait is present.

9. 3. Principle of Segregation
- genes are separated during sex cell
production.
4. Principle of Independent Assortment
- alleles(forms of a gene) are separated
independently to sex cells.
Different traits are not linked together.
Ex. Seed color with plant height