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Chapter 9: DNA: The Molecule of Heredity At a Glance

Case Study: Sunshine Perils

9.1 How Did Scientists Discover That Genes Are Made of DNA?

• Transformed Bacteria Revealed the Link Between Genes and DNA

9.2 What Is the Structure of DNA?

• DNA Is Composed of Four Nucleotides
• DNA Is a Double Helix of Two Nucleotide Strands
• Hydrogen Bonds Between Complementary Bases Hold the Two DNA Strands Together
• The Order of Nucleotides in DNA Can Encode Vast Amounts of Information

Scientific Inquiry: The Discovery of the Double Helix

9.3 How Does DNA Replication Ensure Genetic Constancy During Cell Division?

• The Replication of DNA Is a Critical Event in a Cell’s Life
• DNA Replication Produces Two DNA Double Helices, Each with One Old Strand and One New Strand

A Closer Look: DNA Replication

• Proofreading Produces Almost Error-Free Replication of DNA
• Mistakes Do Happen

Case Study Revisited: Sunshine Perils

Links to Life: Tyrannosaurus rex Reborn?