Chapter 3 Lecture
Concepts of Genetics
Tenth Edition
Mendelian Genetics
Chapter 3 Lecture
http://www.mendelweb.org
Figure 3.1
3.1 Mendel Used a Model Experimental
Approach to Study Patterns of
Inheritance
3.2 The Monohybrid Cross Reveals How
One Trait Is Transmitted from
Generation to Generation
Mendel’s First Three Postulates:
• Pairs of Unit Factors of Inheritance
(aka “genes”)
• Dominance/Recessiveness
• Principle of Segregation
Figure 3.2
Figure 3.3
Fig 3-3
How can we determine the
genotype of an organism
displaying a dominant phenotype?
3.2 The Monohybrid Cross Reveals How
One Trait Is Transmitted from
Generation to Generation
3.2.5 The Testcross: One Character
Figure 3.4
Figure 3.4a
Figure 3.4b
3.3 Mendel’s Dihybrid Cross Generated a
Unique F2 Ratio
Figure 3.5
Figure 3.6
Mendel’s Dihybrid Cross
Revealed His Fourth
Postulate: Independent
Assortment
Figure 3.7
Fig 3-7
Fig 3-7
How many phenotypes and genotypes
do you expect among the F2
generation?
Fig 3-7
3.3 Mendel’s Dihybrid Cross Generated a
Unique F2 Ratio
3.3.2 The Testcross: Two Characters
3.4 The Trihybrid Cross Demonstrates That
Mendel’s Principles Apply to
Inheritance of Multiple Traits
Trihybrid cross
???
Figure 3-8
3.4 The Trihybrid Cross Demonstrates That
Mendel’s Principles Apply to
Inheritance of Multiple Traits
3.4.1 The Forked-Line Method, or Branch Diagram
Figure 3.9
Table 3.1
3.5 Mendel’s Work Was Rediscovered in
the Early Twentieth Century
The Correlation of Mendel’s Postulates
with the Behavior of Chromosomes
Provided the Foundation of Modern
Transmission Genetics
Unit Factors, Genes, and Homologous
Chromosomes
Figure 3.10
Figure 3.10a
Figure 3.10b
Figure 3.10c
3.6 Independent Assortment Leads to
Extensive Genetic Variation
3.7 Laws of Probability Help to Explain
Genetic Events
3.8 Chi-Square Analysis Evaluates the
Influence of Chance on Genetic Data
3.8.1 Chi-Square Analysis and the Null Hypothesis
Table 3.3
Figure 3.11ab
Figure 3.11a
Figure 3.11b
3.9
Pedigrees Reveal Patterns of
Inheritance of Human Traits
3.9.1 Pedigree Conventions
Figure 3.12
3.9
Pedigrees Reveal Patterns of
Inheritance of Human Traits
3.9.2 Pedigree Analysis
Figure 3.13a
Figure 3.13b
Chapt 3, Prob 21
Tt
Tt
tt
or Tt Tt
2/3TT
chance
1/2 x 2/3 =1/3 chance Tt
1/3 chance Tt
So, chance that child hasTay Sachs (tt)=
1/4 x 1/3 x 1/3 = 1/36
Table 3.4