Section 2 Human GeneticsChapter 12
Objectives• Analyze pedigrees to determine how genetic traits and
genetic disorders are inherited.
• Summarize the different patterns of inheritance seen in genetic traits and genetic disorders.
• Explain the inheritance of ABO blood groups.
• Compare sex-linked traits with sex-influenced traits.
• Explain how geneticists can detect and treat genetic disorders.
Section 2 Human GeneticsChapter 12
Inheritance of Traits
• Pedigrees – Geneticists use pedigrees to trace diseases or
traits through families. – Pedigrees are diagrams that reveal inheritance
patterns of genes.
Chapter 12Section 2 Human Genetics
Pedigree for Cystic Fibrosis
Chapter 12
Some Important Genetic Disorders
Section 2 Human Genetics
Autosomal recessive disorders
a. Tay Sachs
b. PKU- Phenylketonuria
c. Albinism
d. cystic fibrosis
Sickle-Cell Anemia (Autosomal Recessive)
Huntington’s Disease (Autosomal Dominant)
Autosomal Dominant
a. achondroplasia (dwarfism)
b. 15 year girls
Section 2 Human GeneticsChapter 12
Genetic Traits and Disorders
• Polygenic Inheritance– Polygenic characters, such as skin color, are
controlled by two or more genes.
Section 2 Human GeneticsChapter 12
Genetic Traits and Disorders, continued
• Sex-influenced Trait– A sex-influenced trait, such as pattern baldness, is
expressed differently in men than in women even if it is on an autosome and both sexes have the same genotype.
Section 2 Human GeneticsChapter 12
Detecting Genetic Disease
• Genetic counseling informs screened individuals about problems that might affect their offspring.
Section 2 Human GeneticsChapter 12
Detecting Genetic Disease
• Genetic screening examines a person’s genetic makeup through blood test.
Section 2 Human GeneticsChapter 12
Detecting Genetic Disease
• Amniocentesis and chorionic villi sampling help physicians test a fetus for the presence of genetic disorders.
• Ultrasounds
Chapter 12
Click below to watch the Visual Concept.
Visual Concept
Comparing Single Allele, Multiple Allele, and Polygenic Traits
Section 2 Human Genetics
Chapter 12
Click below to watch the Visual Concept.
Visual Concept
Comparing Complete, Incomplete,and Co-Dominance
Section 2 Human Genetics
Chapter 12
Click below to watch the Visual Concept.
Visual Concept
Comparing X-Linked and Sex-Influenced Traits
Section 2 Human Genetics
Section 2 Human GeneticsChapter 12
Objectives• Analyze pedigrees to determine how genetic traits and
genetic disorders are inherited.
• Summarize the different patterns of inheritance seen in genetic traits and genetic disorders.
• Explain the inheritance of ABO blood groups.
• Compare sex-linked traits with sex-influenced traits.
• Explain how geneticists can detect and treat genetic disorders.