Unit B4 Molecules Proteins


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Unit B4 Molecules Proteins

  1. 1. Proteins—get ready! <ul><li>Chemical Composition </li></ul><ul><li>Elements: C , H , O , N , and sometimes S . </li></ul><ul><ul><li>Sulphur is unique to this group. </li></ul></ul><ul><li>Functions </li></ul><ul><li>Structural components for each of the following molecules: </li></ul><ul><ul><li>Enzymes (amyl ase , pepsin, trypsin, peptid ase , malt ase , lip ase , nucle ase , DNA/RNA polymer ase etc.) act as catalysts for all cellular chemical reactions. </li></ul></ul>
  2. 2. Some more structural functions! <ul><li>A group of protein hormones (thyroxin, insulin, oxytocin etc.) aids metabolism and provides physiological effects . </li></ul><ul><li>Red blood cells /RBC’s (made up of hemoglobin (Hb) transports oxygen/carbon dioxide and act as buffers . </li></ul>
  3. 3. Remember this one? <ul><li>Cell membrane (scattered proteins and glycoproteins) allows the passage of water, ions, small molecules, amino acids and recognizes foreign cells and microorganisms(glycoprotein) </li></ul>
  4. 4. Wow—proteins do a lot!! <ul><li>Ligaments , tendons and bone (collagen) provide bone and muscle attachments, strength and stability; muscle (actin, myosin) facilitates movement. </li></ul>
  5. 5. Additional functions <ul><li>Hair and nails </li></ul><ul><ul><li>keratin </li></ul></ul>
  6. 6. OK…the last of the functions…for now <ul><li>Antibodies (Y-shaped proteins) deactivates antigens (See C6). </li></ul><ul><li>Microfilaments (cytoskeleton filaments/contractile proteins) provide movement of synaptic vesicles in neurons (See nervous system). </li></ul>
  7. 7. Monomers <ul><li>amino acids (áá). </li></ul><ul><li>approximately 20 different amino acids are produced by the body. These amino acids can be arranged in many combinations and sequences. This accounts for the countless number of unique proteins with only 20 different amino acids! </li></ul>
  8. 8. *Molecular Structure of Amino Acids
  9. 9. Let’s learn how to draw one!
  10. 11. And Finally
  11. 12. Ta Da!!
  12. 13. All right let’s try it out…
  13. 15. And the rest of it
  14. 16. Formation <ul><li>Formation of a protein polymer through dehydration synthesis (-H 2 O ). </li></ul><ul><ul><li>E.g. Collagen, keratin, hemoglobin, glycoproteins, channel and carrier proteins, amyl ase , malt ase , pepsin, insulin, oxytocin etc. </li></ul></ul><ul><li>A peptide bond forms between the joining amino acids/monomers. </li></ul><ul><li>Dehydration synthesis occurs in the liver and body cells. </li></ul>
  15. 18. Breaking down <ul><li>Formation of a protein monomer through hydrolysis ( +H 2 O ). </li></ul><ul><ul><li>E.g. the many different amino acids; lysine, tyrosine, phenylalanine, tryptophan, valine, glutamate etc. </li></ul></ul><ul><li>Peptide bonds between the amino acids are destroyed within the protein polymer. </li></ul><ul><li>Hydrolysis occurs in your stomach and small intestine. </li></ul>
  16. 20. Some animations….if we have time <ul><li>http://www2.nl.edu/jste/proteins.htm </li></ul><ul><li>http://www.coolschool.ca/lor/BI12/unit2/U02L01.htm (2 Videos on Proteins) </li></ul><ul><li>http://trc.ucdavis.edu/biosci10v/bis10v/media/ch02/peptide_bonding.html </li></ul>
  17. 21. So how do we name proteins? <ul><li>(a) Protein/polymer containing 2áá = di peptide </li></ul><ul><li>(b) Protein/polymer containing 3áá = tri peptide </li></ul><ul><li>(c) Protein/polymer containing >3áá = poly peptide </li></ul>
  18. 22. Polymers of Proteins <ul><li>Collagen – ligaments, tendons and bone </li></ul><ul><li>Keratin – hair and nails </li></ul><ul><li>Hemoglobin (Hb) – red blood cells (RBC) </li></ul><ul><li>Glycoproteins, channel, carrier and receptor proteins, – cell membrane proteins </li></ul><ul><li>Enzymes – amyl ase , lip ase , malt ase , pepsin, trypsin, peptid ase , nucle ase , DNA and RNA polymer ases , etc. </li></ul><ul><li>Hormones – thyroxin, insulin, oxytocin, ADH, FSH, LH, epinephrine </li></ul><ul><li>Antibodies </li></ul><ul><li>Microfilaments – cytoskeleton and neurons </li></ul><ul><li>Actin, Myosin – muscles </li></ul>
  19. 23. Levels of Protein Organization (see diagrams) <ul><li>Proteins have 4 levels of organization wrt structure . </li></ul><ul><li>Each level has unique bonding in order to hold its shape and sequence of amino acids. </li></ul>
  20. 28. Primary Structure (1°) <ul><li>Linear sequence of áá joined by peptide bonds . </li></ul><ul><li>Formed by dehydration synthesis. </li></ul><ul><li>Polypeptides differ in the sequence and number of áá. </li></ul>H 2 0
  21. 29. Secondary Structure (2°) <ul><li>α-helix (alpha helix) or  -pleated helix (beta helix) , held together by peptide bonds but H-bonds stabilize the “turns” or “pleated sheet” of the helix. </li></ul><ul><ul><li>E.g. Collagen, keratin. </li></ul></ul>
  22. 31. Tertiary Structure (3°) <ul><li>Forms a 3D shape, which is an α-helix, twisted, bent, and folded. </li></ul><ul><li>Held together by H-bonds , and covalent and ionic bonds of the R-groups. </li></ul><ul><ul><li>E.g. Enzymes such as amyl ase , lip ase , malt ase , pepsin, trypsin, peptid ase , nucle ase , DNA/RNA polymer ases etc. </li></ul></ul>
  23. 34. Note: <ul><li>Shape of protein is very important to its function. </li></ul><ul><li>Exposure to extreme temperatures , pH and heavy metals (Hg, Pb) will change the shape of proteins permanently by destroying the bonds and these molecules will no longer be able to function. </li></ul><ul><ul><li>E.g. changes in temperature , pH , and heavy metals will cause enzymes to denature ; therefore their 3D shape is destroyed and they will not be able to catalyze/speed up the rate of a reaction. </li></ul></ul>
  24. 35. Quaternary structure (4°) <ul><li>Two or more linked polypeptides / subunits. </li></ul><ul><li>Held together by bonding between polypeptide 1 & 2 / subunits and the other specific bonds. </li></ul><ul><ul><li>E.g. Hemoglobin (Hb) is made up of four subunits, each containing ‘globin’ and ‘heme’ portions. </li></ul></ul>
  25. 38. http://trc.ucdavis.edu/biosci10v/bis10v/media/ch02/hemoglobin_quaternary.html (Animation of Hb)
  26. 40. <ul><li>ausgespielt </li></ul><ul><li>En finis </li></ul><ul><li>terminado </li></ul>