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Proteins

Proteins. 2005-2006. 6. proteins : 1. contain C, H, O, N 2. building blocks are amino acids 3. account for more than 50% of the dry mass of most cells Variable group: gives unique properties to each aa. Most structurally & functionally diverse group of biomolecules Function:

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Proteins

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  1. Proteins 2005-2006

  2. 6. proteins: 1. contain C, H, O, N 2. building blocks are amino acids 3. account for more than 50% of the dry mass of most cells Variable group: gives unique properties to each aa

  3. Most structurally & functionally diverse group of biomolecules Function: involved in almost everything enzymes structure (keratin, collagen) carriers & transport (membrane channels) receptors & binding (defense) contraction (actin & myosin) signaling (hormones) storage (bean seed proteins)

  4. The 20 amino acids of proteins

  5. Structure: monomer = amino acids 20 different amino acids polymer = polypeptide protein can be 1 or more polypeptide chains folded & bonded together large & complex molecules complex 3-D shape

  6. Building proteins Peptide bonds: dehydration synthesis linking NH2 of 1 amino acid to COOH of another C–N bond peptidebond

  7. Protein structure & function function depends on structure 3-D structure twisted, folded, coiled into unique shape hemoglobin collagen pepsin lipase 2005-2006

  8. Four Levels of Protein Structure • Primary • Secondary (two types) • Tertiary • Quaternary (two or more polypeptide subunits interact to form a functional protein) • at each level, forces maintain a specific shape http://www.stolaf.edu/people/giannini/flashanimat/proteins/protein%20structure.swf

  9. Protein structure & function function depends on structure all starts with the order of amino acids what determines that order of amino acids? lysozyme: enzyme in tears & mucus that kills bacteria the 10 glycolytic enzymes used to breakdown glucose to make ATP 2005-2006

  10. Protein Folding 1. http://www.learner.org/courses/biology/archive/animations/hires/a_proteo1_h.html 2. http://bioscience.jbpub.com/cells/Media.aspx 3. http://www.youtube.com/watch?v=swEc_sUVz5I

  11. Primary Each amino acid is held together by peptide bonds Forms linear line

  12. Sickle cell anemia http://cbm.msoe.edu/includes/swf/NewestSickleCell.swf

  13. Secondary Two types: alpha helix (twisted) and beta pleated sheet (bent) Formed by hydrogen bonds

  14. Secondary (2°) structure

  15. Tertiary highly-folded polypeptide Forces: interactions between the side chains (R groups) of the various amino acids; hydrophobic interactions, ionic bonds, hydrogen bonding, disulfide bridges (between 2 cysteine aa)

  16. Quaternary The overall protein structure that results from the aggregation of two or more polypeptide subunits; protein can be fibrous or globular. Forces: same as tertiary

  17. Chaperonin proteins Guide protein folding provide shelter for folding polypeptides keep the new protein segregated from cytoplasmic influences 2005-2006

  18. Protein structure (review) multiplepolypeptides hydrophobic interactions aa sequence peptide bonds determinedby DNA R groups H bonds R groups hydrophobic interactions, disulfide bridges 3° 1° 2° 4° 2005-2006

  19. Protein models Protein structure visualized by X-ray crystallography extrapolating from amino acid sequence computer modelling lysozyme

  20. consists of monomers called nucleotides two types : DNA and RNA Contain C,H,O,N, and P Nucleic Acids

  21. Let’s build some Proteins!

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