Chapter 3 Nature of Biochemical Processes
Key Terms <ul><li>Metabolism  – 1000’s of chemical reactions in organisms. Gives off heat depending on metabolic rate </li...
Key terms (continued) <ul><li>Exergonic  reactions release energy and involve the breakdown of complex molecules (cataboli...
<ul><li>Reactions are controlled/regulated by biochemical pathways (enzymes) </li></ul><ul><li>Exergonic and endergonic re...
Antioxidant <ul><li>Antioxidants prevent tissue damage by preventing oxidative reactions (energy releasing) as they can da...
ATP <ul><li>Mitochondria produce ATP (adenosine triphosphate). Energy is released when ATP is hydrolysed (split by adding ...
 
Enzymes <ul><li>Biological  catalysts . A catalyst speeds up (catalyses) a chemical reaction that would otherwise take pla...
 
<ul><li>Enzymes: </li></ul><ul><li>- are substrate specific </li></ul><ul><li>- can be used over and over again </li></ul>...
Enzymes <ul><li>Enzymes may require other  cofactors  to work </li></ul><ul><li>eg. Metallic ions like Zinc </li></ul><ul>...
Enzymes and their substrates <ul><li>Enzymes act only on specific substrates – the active site binds to a part of the subs...
Induced fit
Lock and key
Activation energy and enzymes <ul><li>Chemical reactions involve the breaking and remaking of chemical bonds.  </li></ul><...
Activation energy
Factors affecting enzyme activity <ul><li>pH </li></ul><ul><li>Change in pH can change the shape of the enzyme. </li></ul>...
Factors affecting enzyme activity <ul><li>Temperature </li></ul><ul><li>Optimal temperature approx. 37 </li></ul><ul><li>H...
Factors affecting enzyme activity <ul><li>Enzyme concentration </li></ul><ul><li>Only small amounts required </li></ul><ul...
Enzyme inhibition <ul><li>Other molecules compete with substrate for the active site and may bind permanently. </li></ul><...
Enzyme inhibition <ul><li>Competitive inhibitor – competes for active site an binds permanently. Eg. O 2  on rubisco enzym...
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Enzymes

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Enzymes

  1. 1. Chapter 3 Nature of Biochemical Processes
  2. 2. Key Terms <ul><li>Metabolism – 1000’s of chemical reactions in organisms. Gives off heat depending on metabolic rate </li></ul><ul><li>Catabolic – breakdown of complex molecules into simpler molecules. Energy is released (exergonic). </li></ul><ul><li>Anabolic – atoms and molecules are joined to build complex molecules. Energy is required (endergonic) </li></ul>
  3. 3. Key terms (continued) <ul><li>Exergonic reactions release energy and involve the breakdown of complex molecules (catabolic) egs. Oxidation and respiration </li></ul><ul><li>Endergonic reactions consume energy and involve building complex molecules (anabolic) egs. Reduction and photosynthesis </li></ul>
  4. 4. <ul><li>Reactions are controlled/regulated by biochemical pathways (enzymes) </li></ul><ul><li>Exergonic and endergonic reactions happen simultaneously. ATP carries energy to necessary locations in the cell. </li></ul>
  5. 5. Antioxidant <ul><li>Antioxidants prevent tissue damage by preventing oxidative reactions (energy releasing) as they can damage the cells </li></ul><ul><li>(see page 61 of Nature of Biology) </li></ul>
  6. 6. ATP <ul><li>Mitochondria produce ATP (adenosine triphosphate). Energy is released when ATP is hydrolysed (split by adding H 2 O). ADP and a phosphate molecule are the products. </li></ul>
  7. 8. Enzymes <ul><li>Biological catalysts . A catalyst speeds up (catalyses) a chemical reaction that would otherwise take place at a much slower rate. </li></ul><ul><li>Enzymes: </li></ul><ul><li>- are proteins (usually folded to create a specific active site ) </li></ul>
  8. 10. <ul><li>Enzymes: </li></ul><ul><li>- are substrate specific </li></ul><ul><li>- can be used over and over again </li></ul><ul><li>- are needed in small amounts (they are not reactants or products) </li></ul><ul><li>- reduce energy needed for a reaction to happen ( activation energy ) </li></ul><ul><li>- can catalyse a reaction in either direction </li></ul><ul><li>- do not increase the final amount of product </li></ul>
  9. 11. Enzymes <ul><li>Enzymes may require other cofactors to work </li></ul><ul><li>eg. Metallic ions like Zinc </li></ul><ul><li>Organic molecules that act as cofactors are called coenzymes </li></ul><ul><li>eg. vitamins </li></ul>
  10. 12. Enzymes and their substrates <ul><li>Enzymes act only on specific substrates – the active site binds to a part of the substrate. </li></ul><ul><li>Lock and key </li></ul><ul><li>Induced fit (see pg 66, Fig 3.10) </li></ul><ul><li>Poisons block active sites and stop enzyme action </li></ul>
  11. 13. Induced fit
  12. 14. Lock and key
  13. 15. Activation energy and enzymes <ul><li>Chemical reactions involve the breaking and remaking of chemical bonds. </li></ul><ul><li>Energy needed to get reaction started (called activation energy) </li></ul><ul><li>Enzymes act by reducing the activation energy (see Fig. 3.8, p65) </li></ul>
  14. 16. Activation energy
  15. 17. Factors affecting enzyme activity <ul><li>pH </li></ul><ul><li>Change in pH can change the shape of the enzyme. </li></ul><ul><li>Biological fluids normally in the range 6–8 </li></ul><ul><li>Optimal pH for each enzyme </li></ul><ul><li>eg. Pepsin – stomach (2) </li></ul><ul><li> Trypsin – small intestine (8) </li></ul>
  16. 18. Factors affecting enzyme activity <ul><li>Temperature </li></ul><ul><li>Optimal temperature approx. 37 </li></ul><ul><li>High temperature leads to denaturation </li></ul><ul><li>Low temperature is preserving; will reactivate at optimal temperature </li></ul>
  17. 19. Factors affecting enzyme activity <ul><li>Enzyme concentration </li></ul><ul><li>Only small amounts required </li></ul><ul><li>Increased enzyme conc. leads to increased production rate </li></ul><ul><li>Substrate concentration </li></ul><ul><li>Increase in substrate will increase production rate only until all active sites are in use </li></ul>
  18. 20. Enzyme inhibition <ul><li>Other molecules compete with substrate for the active site and may bind permanently. </li></ul><ul><li>Interferes with enzyme function and may be lethal eg. cyanide </li></ul>
  19. 21. Enzyme inhibition <ul><li>Competitive inhibitor – competes for active site an binds permanently. Eg. O 2 on rubisco enzyme in C3 plants instead of CO 2 </li></ul><ul><li>Non-competitive inhibitor – doesn’t bind with the active site permanently. </li></ul>

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