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The Vital Role of Enzymes: Catalysts of Life's Chemical Reactions

Enzymes are fundamental proteins that act as "helpers" in biochemical processes, facilitating chemical reactions crucial for sustaining life. They enable dehydration synthesis and hydrolysis, which are essential for building and breaking down molecules, including those involved in digestion. Each enzyme is specific to a particular reaction and must maintain the correct shape to perform its function. Various factors, such as temperature and pH, can affect enzyme activity. Understanding enzymes is key to exploring all chemical reactions in living organisms.

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The Vital Role of Enzymes: Catalysts of Life's Chemical Reactions

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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 DEHYDRATION SYNTHESIS!!!! HYDROLYSIS! • Processes of life • building molecules • synthesis • breaking down molecules • digestion

  4. enzyme + enzyme + Nothing works without enzymes! • How important are enzymes? • all chemical reactions in living organisms require enzymes to work • building molecules • synthesis enzymes • breaking down molecules • digestive enzymes • enzymes speed up reactions or slow down reactions • “catalysts” “inhibitors”

  5. + enzyme enzyme + Examples • synthesis • digestion

  6. 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 help • sucrase breaks down sucrose • proteases breakdown proteins • lipases breakdown lipids • DNA polymerase builds DNA

  7. active site 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 enzyme

  8. It’s shape that matters! • Lock & Key model • shape of protein allows enzyme & substrate to fit • Induced-fit model • Once the enzyme and substrate join together, the enzyme molds itself around the substrate, allowing the reaction to occur • Like how a glove fits your hand…

  9. 2 PLAY 1 3

  10. 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

  11. 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

  12. 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

  13. 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

  14. 37° Temperature humanenzymes reaction rate temperature

  15. How do cold-blooded creatures do it?

  16. 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

  17. pH stomachpepsin intestinestrypsin reaction rate 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

  18. For enzymes…What matters? SHAPE!

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