1. Primary Structure: Polypeptide chain Polypeptide chain Amino acid monomers Peptide linkages Figure 3.6 The Four Levels of Protein Structure

2. Secondary Structure: a.  Helix 1. Primary Structure: Polypeptide chain Hydrogen bond Figure 3.6 The Four Levels of Protein Structure

2. Secondary Structure: a.  Helix 1. Primary Structure: Polypeptide chain b.  Pleated sheet Hydrogen bond Figure 3.6 The Four Levels of Protein Structure

3. Tertiary Structure: Polypeptides fold 2. Secondary Structure: a.  Helix 1. Primary Structure: Polypeptide chain b.  Pleated sheet Disulfide bond  Pleated sheet  Helix Figure 3.6 The Four Levels of Protein Structure

4. Quaternary Structure: Polypeptides assemble into larger molecules 3. Tertiary Structure: Polypeptides fold 2. Secondary Structure: a.  Helix 1. Primary Structure: Polypeptide chain b.  Pleated sheet Figure 3.6 The Four Levels of Protein Structure