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7.5

7.5. Proteins. 7.5.1 Explain the four levels of protein structure, indicating the significance of each level. 1°- sequence of amino acids in the chain 2°- coils; H bonds; collagen, keratin have repeated sequences so have lots coils α -helix: hair, wool, horns, feathers

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7.5

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  1. 7.5 Proteins

  2. 7.5.1 Explain the four levels of protein structure, indicating the significance of each level. 1°- sequence of amino acids in the chain 2°- coils; H bonds; collagen, keratin have repeated sequences so have lots coils α-helix: hair, wool, horns, feathers β-pleated sheet: silk

  3. 7.5.1 Explain the four levels of protein structure, indicating the significance of each level. 3°- helix folding; R groups interact: hydrophobics cluster together on inside, hydrophilics cluster on outside, disulfide bridges between S of 2 R groups (cov bond), ions may be cofactors

  4. 7.5.1 Explain the four levels of protein structure, indicating the significance of each level. 4°- different polypeptides combine w/H bonds, +/- attractions, hydrophobic forces, and/or disulfide bridges; common in large globular proteins (hemoglobin—2 α chains, 2 β chains) “conjugated proteins” - binding of prosthetic group: each chain also has a Heme group, contains Fe (not a polypeptide) chlorophyll, electron transport chain enzymes are other examples

  5. 7.5.2 Outline the difference between fibrous proteins & globular proteins, with reference to two examples of each protein type.

  6. 7.5.3 Explain the significance of polar and non-polar amino acids. • 20 common amino acids • 8 w/non-polar R groups • Insoluble in water • Cluster together @ center (4° structure) • More non-polar AAs  less soluble in water • Cell membrane (phospholipid bilayer): polar on outside, non on inside • Protein situated with hydrophilic portions to outside of membrane, hydrophobic sections to center

  7. 7.5.4 State four functions of proteins, giving a named example of each: • Structure: collagen (fibrous, structural ptn) builds tendons & in skin • Enzymes: all are globular • starch –amylase maltose • Transport: hemoglobin (globular, conjugated); readily, reversibly binds Oxygen b/c of heme group

  8. 7.5.4 State four functions of proteins, giving a named example of each: • Hormones: some are ptns (some are steroids) • Insulin • Contractile: muscle contractions (actin, myosin) • Defense: antibodies/immunoglobulins for defense against antigens

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