Chapter 11: Introduction to Genetics

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

1. Genetics The scientific study of how traits are
   passed from generation to generation (heredity)

4

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

5

1. 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

• Mendels 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

1. The Principle of Dominance states that some
   alleles are dominant and others are recessive.
2. Dominant an organism will always exhibit the
   dominant form of a trait if it is present.
   Characterized by use of a capital letter (A)
3. Recessive an organism will ONLY show the
   recessive trait if it doesnt have an allele for
   the dominant trait. Characterized by use of a
   lower case letter (a)

9
Mendels Seven F1 Crosses on Pea Plants
Section 11-1
Seed Shape
Flower Position
Seed Coat Color
Seed Color
Pod Color
Plant Height
Pod Shape
Round
Yellow
Gray
Smooth
Green
Axial
Tall
Wrinkled
Green
White
Constricted
Yellow
Terminal
Short
Round
Yellow
Gray
Smooth
Green
Axial
Tall
10
Mendels Two Laws

• Mendels 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

1. Law of Independent Assortment the alleles for
   different genes do not influence each others
   inheritance.

13
Concept Map
alleles for different genes do not influence
each others inheritance.
which is called the
Section 11-3
Gregor Mendel
Law of Independent Assortment
concluded that
experimented with
which is called the
which is called the
Principle of Unit Factors