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Chapter 12: Patterns of Inheritance At a Glance

Case Study: Marfan Syndrome

12.1 How Did Gregor Mendel Lay the Foundation for Modern Genetics?

• Doing It Right: The Secrets of Mendel’s Success

12.2 How Are Single Traits Inherited?

• The Inheritance of Dominant and Recessive Alleles on Homologous Chromosomes Can Explain the Results of Mendel’s Crosses
• Mendel’s Hypothesis Can Be Used to Predict the Outcome of New Types of Single-Trait Crosses

12.3 How Are Multiple Traits on Different Chromosomes Inherited?

• Mendel Hypothesized That Genes on Different Chromosomes Are Inherited Independently
• In an Unprepared World, Genius May Go Unrecognized

12.4 How Are Genes Located on the Same Chromosome Inherited?

• Genes on the Same Chromosome Tend to Be Inherited Together
• Recombination Can Create New Combinations of Linked Alleles

12.5 How Is Sex Determined, and How Are Sex-Linked Genes Inherited?

• Sex-Linked Genes Are Found Only on the X or Only on the Y Chromosome

12.6 What Are Some Variations on the Mendelian Rules of Inheritance?

• Incomplete Dominance: The Phenotype of Heterozygotes Is Intermediate Between the Phenotypes of the Homozygotes
• A Single Gene May Have Multiple Alleles

Scientific Inquiry: Cystic Fibrosis

• Many Traits Are Influenced by Several Genes
• Single Genes Typically Have Multiple Effects on Phenotype
• The Environment Influences the Expression of Genes

12.7 How Are Human Genetic Disorders Investigated?

12.8 How Are Human Disorders Caused by Single Genes Inherited?

• Some Human Genetic Disorders Are Caused by Recessive Alleles
  Albinism Results from a Defect in Melanin Production
  Sickle-Cell Anemia Is Caused by a Defective Allele for Hemoglobin Synthesis
• Some Human Genetic Disorders Are Caused by Dominant Alleles
• Some Human Genetic Disorders Are Sex-Linked

12.9 How Do Errors in Chromosome Number Affect Humans?

• Some Genetic Disorders Are Caused by Abnormal Numbers of Sex Chromosomes
  Turner Syndrome (XO)
  Trisomy X (XXX)
  Klinefelter Syndrome (XXY)
  XYY Males

Earth Watch: Modern Medicines from Wild Genes

• Some Genetic Disorders Are Caused by Abnormal Numbers of Autosomes
  • Trisomy 21 (Down Syndrome)

  Case Study Revisited: Marfan Syndrome

  Links to Life: Mendel, Mosquitoes, and Malaria

  
  
  
  
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