1. Chapter 11: Introduction to Genetics
Section 11.1: The work of Gregor Mendel

2. Key Concepts: What is the principle of dominance?
What happens during segregation?

3. A. Genetics and Gregor Mendel
Genetics – The scientific study of how traits are passed from generation to generation (heredity)

4. Gregor Mendel – Australian monk that is known as the “Father of Genetics
performed experiments using garden peas.
Mendel controlled the pollination by a process called CROSS-POLLINATION

5. Cross pollination – the process of cutting away the male pollen producing parts then dusting pollen from another plant onto the female part of the flower.

6. B. Genes and Dominance
Mendel’s work led him to discover two principles:
Principle of Unit factors.
Principle of Dominance
The Principle of Unit factors states that inheritance is controlled by factors that are passed from one generation to the next. These factors are called TRAITS.
Trait – a specific characteristic (height, color, etc) that varies from one individual to another

7. Hybrid – the off spring of crosses between parents with different traits.
Genes - chemical factors that determine traits
Alleles – the different forms of an allele.
Example: The trait “height” has two alleles; one for “short” and one for “tall”

8. The Principle of Dominance states that some alleles are dominant and others are recessive.
Dominant – an organism will always exhibit the dominant form of a trait if it is present. Characterized by use of a capital letter (A)
Recessive – an organism will ONLY show the recessive trait if it doesn’t have an allele for the dominant trait. Characterized by use of a lower case letter (a)

9. Mendel’s Seven F1 Crosses on Pea Plants
Section 11-1
Seed Shape
Seed Color
Seed Coat
Color
Pod
Shape
Pod Color
Flower Position
Plant Height
Round
Yellow
Gray
Smooth
Green
Axial
Tall
Wrinkled
Green
White
Constricted
Yellow
Terminal
Short
Round
Yellow
Gray
Smooth
Green
Axial
Tall

10. Mendel’s Two Laws
Mendel’s work also led to the discovery of two laws associated with Genetics:
Law of Segregation
Law of Independent Assortment

11. Law of Segregation –
each organism has two copies of a gene (1 from each parent).
These genes are segregated (separated) from each other when gametes are formed

12. Law of Independent Assortment – the alleles for different genes do not influence each other’s inheritance.

13. Concept Map Gregor Mendel alleles for different genes do
not influence each
other’s inheritance.
which is called the
Section 11-3
Gregor
Mendel
Law of Independent Assortment
experimented with
concluded that
Pea
plants
“Factors”
determine
traits
Some alleles
are dominant,
and some alleles
are recessive
Alleles are
separated during
gamete formation
which is called the
which is called the
which is called the
Principle of Unit Factors
Principle of
Dominance
Law of
Segregation