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Enzymes

Enzymes. Ms. Kim-Honors Biology. Enzymes. Special type of protein (a catalyst) that speeds up chemical reactions by lowering activation energy Involved in most chemical reactions. CH 2 OH. CH 2 OH. CH 2 OH. CH 2 OH. O. O. O. O. H. H. H. H. H. H. H. Sucrase. H. OH. H. HO.

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Enzymes

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  1. Enzymes Ms. Kim-Honors Biology

  2. Enzymes • Special type of protein (a catalyst) that speeds up chemical reactions by lowering activation energy • Involved in most chemical reactions

  3. CH2OH CH2OH CH2OH CH2OH O O O O H H H H H H H Sucrase H OH H HO OH H HO H2O + O H OH H O HO CH2OH CH2OH OH H H H OH OH H OH Fructose Glucose Sucrose Figure 8.13 C12H22O11 C6H12O6 C6H12O6 Chemical Reaction • Every chemical reaction between molecules • Involves both bond breakingand bond forming

  4. Why Enzymes again…? • Enzymes lower the activation energy • Lower the hill that you have to roll the ball up • Chemical reactions happen faster

  5. Unaffected by enzyme

  6. Substrate Specificity of Enzymes • The substrate • Is the reactant an enzyme acts on • The enzyme • Binds to its substrate, forming an enzyme-substrate complex

  7. NOTE: Oxygen gas(O2) forms BUBBLES ENZYME SUBSTRATE (REACTANT) PRODUCTS

  8. Substrate Active site Enzyme Figure 8.16 (a) • The active site • Is the region on the enzyme where the substrate binds Most enzyme-substrate interactions  result of weak bonds.

  9. How do enzymes work??? • Lock and Key Theory • Substrate (key)  a specific reactant acted upon by the enzyme (lock) • Active Site changes the chemical bonds of the substrate  causes a reaction  forms new products! • Enzyme remains unchanged!

  10. How do Enzymes work? • Lock & Key • Substrate (key) • A specific reactant • Enzyme (lock) • Active site is where the lock and key meet

  11. Lock and Key • Active site (where the lock and key meet) changes the chemical bond • Creates a reaction = New products Perfect fit of the lock and key = a PERFECT reaction **Enzymes DON’T CHANGE SHAPE

  12. Enzyme- substrate complex (b) Figure 8.16 • Induced fitof a substrate • “tight” fit  creates a “microenvironment” • Weakens bonds  gets to transition state faster

  13. Enzyme is RECYCLED!!Never used up or destroyed

  14. Enzymes • Help us by: • Metabolism  Help break down food • Found in digestive system, mouth • Put together proteins • Part of immune system • Work best when • Optimal pH – too acidic/basic bonds break • Optimal temperature – too hot, enzymes denature

  15. Optimal temperature for typical human enzyme Optimal temperature for enzyme of thermophilic (heat-tolerant) bacteria Rate of reaction 80 0 20 100 40 Temperature (Cº) (a) Optimal temperature for two enzymes Figure 8.18 EFFECTS OF TEMPERATURE & pH • Enzymes have an optimal temperature and pH in which it can function

  16. Optimal pH for pepsin (stomach enzyme) Optimal pH for trypsin (intestinal enzyme) Rate of reaction 5 6 7 8 9 3 4 0 2 1 (b) Optimal pH for two enzymes Figure 8.18 • Enzymes have an optimal pH in which it can function

  17. What factors denature proteins? Denaturation = take away (or lower) the function of protein • pH • Salt concentration • Temperature

  18. Denaturation • If a protein is exposed to extreme temperatures, levels of pH, or salt contents, the bonds can start to break and the structure starts to unravel • Therefore, when the structure denatures, the protein will no longer function properly

  19. Examples • Amylase-breaks down starch • Lactase-Breaks down lactose • Lipases-Breaks down fat • Catalase-Breaks down hydrogen peroxide into water and oxygen.

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