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Proteins – Multipurpose molecules

Proteins – Multipurpose molecules

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Proteins – Multipurpose molecules

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  1. Proteins – Multipurpose molecules • Function: • many, many functions • Hormones - Regulation • signals from one body system to another • Insulin – blood sugar levels • movement • muscle and skin • immune system - antibodies • protect against germs • enzymes - written over the arrow • help chemical reactions (metabolism)

  2. H | —C— | H C—OH —N— O || H Proteins • Building block = amino acids • 20 different amino acids Carboxyl group (“acid”) Amino group variable group “R” group (20 different ones)

  3. amino acid amino acid amino acid amino acid amino acid Amino acid chains • Proteins – also called polypeptides • amino acids chained into a polymer by peptide bonds • Each amino acid is different – “R group” • some “like” water & dissolve in it • some “fear” water & separate from it

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

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

  6. collagen (skin) For proteins: SHAPE matters! • Proteins fold & twist into 3-D shape • that’s what happens in the cell! • Different shapes = different jobs/functions • Shape is determined by the order of the amino acids growthhormone hemoglobin red blood cells carries oxygen pepsin (stomach)

  7. It’s SHAPE that matters! • Proteins do their jobs, because of their 3-D shape • Unfolding a protein destroys its shape • wrong shape = can’t do its job • unfolding proteins = “denature” • temperature (high) • pH (acidity) unfolded“denatured” In Biology, it’s not the size, it’s the SHAPEthat matters! folded

  8. enzyme + enzyme + Nothing works without enzymes! • ALL chemical reactions (metabolism) in living organisms require enzymes to do work (GRRSNERT) • building molecules • Synthesis enzymes • breaking down molecules • digestive enzymes • enzymes speed up reactions • “catalysts” – lower activation energy We can’t live without enzymes!

  9. + enzyme enzyme + Examples • Synthesis Same enzyme for BOTH reactions • Digestion - N

  10. Enzymes are proteins • Each enzyme is the specific helper to a specific reaction • each enzyme needs to be the right 3-D shape for the job • enzymes are named for the reaction they help – usually end in -ase • sucrase breaks down sucrose • proteases breakdown proteins • lipases breakdown lipids • DNA polymerase builds DNA Oh, I get it! They end in -ase

  11. active site Enzymes aren’t used up • Enzymes are not changed by the reaction • used only temporarily - reusable • re-used again for the same reaction with other molecules – written over the arrow • very little enzyme needed to help in many reactions product substrate or reactant enzyme enzyme-substrate complex

  12. Enzyme vocabulary • Enzyme • helper protein molecule • Co-enzyme • Usually a vitamin; NOT protein • Substrate • molecule that enzymes work on • Products • what the enzyme helps produce from the reaction • Active site • part of enzyme that substrate molecule fits into

  13. It’s Shape that Matters!!! The “Key” • Lock & Key model • Shape of protein allows enzyme & substrate to fit together • SHAPE of enzyme for each specific reaction

  14. SHAPE! For enzymes…What matters? • Correct protein determined by: • Correct order of amino acids – • determined by DNA • Temperature • pH (acids & bases) • Substrate Concentration (amount of substrate)

  15. Order of amino acids • Wrong order = wrong shape = can’t do its job! foldedprotein chain ofamino acids DNA right shape! foldedprotein chain ofamino acids wrong shape! DNA

  16. Sickle Cells vs Normal RBC’s

  17. Temperature • Effect on rates of enzyme activity • Optimum (best) temperature • greatest number of collisions between enzyme & substrate • human enzymes • 35°- 40°C (body temp = 37°C) • Raise temperature (boiling) - fever • denature protein = unfold = lose shape • Lower temperature T° • molecules move slower • fewer collisions between enzyme & substrate

  18. 37° Temperature humanenzymes What’s happening here?! Enzyme is denaturing or unfolding reaction rate temperature

  19. pH stomachpepsin intestinestrypsin What’s happening here?! reaction rate 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH acid base neutral

  20. Also Substrate concentration • Lucy and the candy factory http://www.youtube.com/watch?v=4wp3m1vg06Q ALL enzymes are in use; can’t go any faster unless more enzymes are added reaction rate Substrate concentration