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Maintaining a Balance

Maintaining a Balance. HSC Course Core Topic 1 - Factors Affecting Activity of Enzymes. Enzyme activity. How fast an enzyme is working = Rate of Reaction. Rate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time. Enzyme activity.

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Maintaining a Balance

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  1. Maintaining a Balance HSC Course Core Topic 1 - Factors Affecting Activity of Enzymes

  2. Enzyme activity How fast an enzyme is working = Rate of Reaction Rate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time.

  3. Enzyme activity Rate of Reaction Variable you are looking at

  4. Factors Affecting Enzyme Activity • Temperature • pH • Substrate concentration • Presence of activators • Coenzymes • Cofactors • Presence of enzyme inhibitors

  5. Temperature The effect: • Most enzymes work best at certain temperatures i.e. 370C in mammals. • The speed of the reaction decreases if the temperature varies from this level. • The activity of most enzymes increases as temperature increase.

  6. Why does it happen? Increased temperature causes molecules to move more rapidly which in turn causes more collisions between molecules. This increases the chances of the substrate colliding with the enzyme’s active site.

  7. Denaturing • If the temperature rises above a certain level, the enzyme denatures (changes it shape so its active site is no longer correctly exposed) to become inactive and can no longer bind with the substrate.

  8. Temperature 5- 40oC Increase in Activity 40oC - denatures Rate of Reaction 0 10 20 30 40 50 60 <5oC - inactive

  9. Each enzyme has it own optimal temperature. The hydrogen bonds holding proteins together are broken by high temperatures and this disrupts their three dimensional shape.

  10. pH pH Rate of Reaction 1 5 7 8 9 2 3 4 6

  11. pH Narrow pH optima Rate of Reaction 1 5 7 8 9 2 3 4 6

  12. pH Narrow pH optima WHY? Rate of Reaction 1 5 7 8 9 2 3 4 6

  13. pH Narrow pH optima Outside this range also disrupt bonding of protein molecule  Changes structure/shape and therefore alters the active site. Rate of Reaction 1 5 7 8 9 2 3 4 6

  14. Enzyme Concentration Rate of Reaction

  15. Enzyme Concentration Rate of Reaction Enzyme Concentration As enzyme concentration increses, rate of reaction increases.

  16. Substrate Concentration Rate of Reaction

  17. Substrate Concentration Rate of Reaction Substrate Concentration As substrate concentration increases, reaction rate increases until all active sites are filled. After this point, the reaction plateaus and can not proceed any faster. This point is called enzyme saturation point.

  18. Substrate Concentration Active sites full- maximum turnover Rate of Reaction Substrate Concentration

  19. Presence of Activators Coenzymes and Cofactors • Coenzymes – Organic molecules that may be required for enzyme activity • Cofactors – Inorganic molecules that may be required for enzyme activity

  20. Presence of Enzyme Inhibitors • Other molecules that block the active site of enzymes. The stop the substrate from binding to the active site.

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