Honors Biology - Enzymes

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  • 1. Enzymes: “Helper” Protein molecules
  • 2. Flow of energy through life  Life is built on chemical reactions
  • 3. Chemical reactions of life  Processes of life  building molecules  synthesis +  breaking down molecules  digestion +
  • 4. Nothing works without enzymes!  How important are enzymes?  all chemical reactions in living organisms require enzymes to work enzyme  building molecules  synthesis enzymes +  breaking down molecules enzyme We can’t live  digestive enzymeswithout enzymes! +  enzymes speed up reactions  “catalysts”
  • 5. Examples  synthesis enzyme +  digestion + enzyme
  • 6. A THREE SLIDE INTERMISSIONThese relate to your “GuidedReading Notes”
  • 7. Endergonic vs. exergonic reactions exergonic endergonic - energy released - energy invested - digestion - synthesis - break down molecules - build molecules
  • 8. Reducing Activation energy  Catalysts  reducing the amount of energy to start a reaction uncatalyzed reaction Pheeew… that takes a lot less energy! catalyzed reaction NEW activation energy reactant product
  • 9. Catalysts  So what’s a cell got to do to reduce activation energy?  get help! … chemical help… ENZYMES Call in the ENZYMES!
  • 10. AND WE ARE BACK…The next slide is #6
  • 11. Enzymes are proteins  Each enzyme is the specific helper to a specific reaction  each enzyme needs to be the right shape for the job  enzymes are named for the reaction they helpOh, I get it!  sucrase breaks down sucrose They end in -ase  proteases breakdown proteins  lipases breakdown lipids  DNA polymerase builds DNA
  • 12. Enzymes aren’t used up  Enzymes are not changed by the reaction  used only temporarily  re-used again for the same reaction with other molecules  very little enzyme needed to help in many reactions substrate product active site enzyme
  • 13. It’s shape that matters!  Lock & Key model  shape of protein allows enzyme & substrate to fit  specific enzyme for each specific reaction
  • 14. 21 3
  • 15. Enzyme vocabulary  Enzyme  helper protein molecule 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
  • 16. What affects enzyme action  Correct protein structure  correct order of amino acids  why? enzyme has to be right shape  Temperature  why? enzyme has to be right shape  pH (acids & bases)  why? enzyme has to be right shape
  • 17. Order of amino acids Wrong order = wrong shape = can’t do its job! folded chain of protein amino acids DNA right shape! folded protein chain of amino acids wrong shape! DNA
  • 18. Temperature Effect on rates of enzyme activity  Optimum temperature  greatest number of collisions between enzyme & substrate  human enzymes  35°- 40°C (body temp = 37°C)  Raise temperature (boiling)  denature protein = unfold = lose shape  Lower temperature T°  molecules move slower  fewer collisions between enzyme & substrate
  • 19. Temperature human What’s enzymes happening here?! reaction rate 37° temperature
  • 20. pH  Effect on rates of enzyme activity  changes in pH changes protein shape  most human enzymes = pH 6-8  depends on where in body  pepsin (stomach) = pH 3  trypsin (small intestines) = pH 8
  • 21. pH stomach intestines What’s happening pepsin trypsin here?!reaction rate 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH
  • 22. For enzymes…What matters? SHAPE!