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Proteins

Proteins . Proteins. Multipurpose molecules. Types of questions.

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Proteins

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  1. Proteins

  2. Proteins Multipurposemolecules

  3. Types of questions • RIGHT THERE  ( The answer is easy to find and the words used to make the question are also in the answer.)THINK AND SEARCH   ( The answer is in the text or your notes but harder to find.  The words to the question and the answer are not in the same sentence.)AUTHOR AND YOU  (Take what the author or teacher tells you and connect it to what you know.)SYNTHESIS (Take what you have learned and put it together with other ideas and what you know.

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

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

  6. H O | —C— | H || C—OH —N— H Amino acids • Structure: • central carbon • amino group • carboxyl group (acid) • R group (side chain) • variable group • confers unique chemical properties of the amino acid R

  7. nonpolar & hydrophobic Nonpolar amino acids Why are these nonpolar & hydrophobic?

  8. polar or charged & hydrophilic Polar amino acids Why are these polar & hydrophillic?

  9. hemoglobin collagen Protein structure & function • Function depends on structure • 3-D structure • twisted, folded, coiled into unique shape pepsin

  10. Primary (1°) structure • Order of amino acids in chain • amino acid sequence determined by gene (DNA) • slight change in amino acid sequence can affect protein’s structure & it’s function • even just one amino acid change can make all the difference! lysozyme: enzyme in tears & mucus that kills bacteria

  11. Sickle cell anemia

  12. Secondary (2°) structure • “Local folding” • folding along short sections of polypeptide • interaction between adjacent amino acids • H bonds between R groups • -helix • -pleated sheet

  13. “Let’s go to the video tape!” (play movie here) Secondary (2°) structure

  14. “Let’s go to the video tape!” (play movie here) Tertiary (3°) structure • “Whole molecule folding” • determined by interactions between R groups • hydrophobic interactions • effect of water in cell • anchored by disulfide bridges(H & ionic bonds)

  15. “Let’s go to the video tape!” (play movie here) Quaternary (4°) structure • More than one polypeptide chainjoined together • only then is it a functional protein • hydrophobic interactions collagen = skin & tendons hemoglobin

  16. Protein Mobile • Two pieces of paper, different color patterns

  17. Result: 5 strips each. Leave one straight, write “primary” on back and “peptide bond” • This is your first level of your mobile. • All the rest of the strips you will fold/twist. • (wait, next slide)

  18. Leaving one strip at the top unfolded,Now twist one set of strips around your finger to form a alpha helix, and another set fan fold to create a pleat. • More red colors = alpha helix • More blue colors = beta pleat • All of rest of strips (4 each, fold accordingly) Beta Pleat Fan fold Alpha helix Twist around finger

  19. Leave one of each folded, write “secondary” and “peptide” on back. All of rest of strips:Wrap around themselves (Tertiary) • Alpha helix: match red to yellow or orange • Beta pleat: match blue to green or purple. • Staple.

  20. Leave on of each wound up to itself as “tertiary”. Write “Polypeptide” on each of them. Remaining strips, Glob them together, staple and label “Quaternary” and “protein” • Staple bluest part to orangest part

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

  22. Denature a protein • Unfolding a protein • disrupt 3° structure • pH salt temperature • unravels or denatures protein • disrupts H bonds, ionic bonds & disulfide bridges • destroys functionality • Some proteins can return to their functional shape after denaturation, many cannot In Biology,size doesn’t matter, SHAPE matters!

  23. Let’s build some Proteins!

  24. Any Questions??

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