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Proteins

Proteins. Proteins:. Multipurpose molecules. insulin. hemoglobin. collagen (skin). Proteins. Examples muscle fingernails, claws skin hair enzymes example: pepsin hormones example: insulin. Proteins. Function: many, many functions hormones insulin movement muscle

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Proteins

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  1. Proteins

  2. Proteins: Multipurpose molecules

  3. insulin hemoglobin collagen (skin) Proteins Examples • muscle • fingernails, claws • skin • hair • enzymes • example: pepsin • hormones • example: insulin

  4. Proteins • Function: • many, many functions • hormones • insulin • movement • muscle • immune system • protect against germs • enzymes • help chemical reactions

  5. H | —C— | H amino acid amino acid amino acid amino acid amino acid – – – – C—OH —N— O || H variable group Proteins • Building block = amino acids • 20 different amino acids

  6. Amino acid chains • Proteins • amino acids chained into a polymer • Each amino acid is different • some “like” water & dissolve in it • some “fear” water & separate from it

  7. Water-fearing amino acids • Hydrophobic • “water fearing” amino acids • try to get away from water in cell • the protein folds

  8. Water-loving amino acids • Hydrophillic • “water loving” amino acids • try to stay in water in cell • the protein folds

  9. collagen 3-D protein structure • Proteins fold & twist into 3-D shape hemoglobin growthhormone pepsin

  10. Proteins (Polypeptides) Four levels of protein structure: A. Primary Structure B. Secondary Structure C. Tertiary Structure D. Quaternary Structure

  11. Amino Acids (aa) aa1 aa2 aa3 aa4 aa5 aa6 Peptide Bonds Primary Structure Amino acidsbonded together by peptide bonds (straight chains)

  12. Alpha Helix Beta Pleated Sheet Hydrogen Bonds Secondary Structure • 3-dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds. • Two examples:

  13. Beta Pleated Sheet Tertiary Structure • Secondary structuresbent and folded into a more complex 3-D arrangement of linked polypeptides • Bonds: H-bonds, ionic, disulfide bridges (S-S) • Call a “subunit”. Alpha Helix

  14. Quaternary Structure • Composed of 2 or more “subunits” • Globular in shape • Form in Aqueous environments • Example: enzymes (hemoglobin) subunits

  15. Its shape that matters! • Proteins do their jobs, because of their shape • Unfolding a protein destroys its shape • wrong shape = can’t do its job • unfolding proteins = “denature” • temperature • pH (acidity) unfolded“denatured” folded

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