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Biochemistry of respiration

Biochemistry of respiration. Raw materials…. Any organic molecule Carbohydrate Lipid Protein. They contain…. …too much chemical energy. So, respiration involves…. …breaking down large complex organic molecules to produce a molecule that contains a small amount of energy. ATP.

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Biochemistry of respiration

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  1. Biochemistry of respiration

  2. Raw materials… • Any organic molecule Carbohydrate Lipid Protein

  3. They contain… …too much chemical energy

  4. So, respiration involves… …breaking down large complex organic molecules to produce a molecule that contains a small amount of energy

  5. ATP ATP is an immediate source of energy because:- • Only one step is necessary to release the energy • The amount of energy released is small enough to be useful.

  6. Aim of respiration • Synthesis of ATP

  7. Carbohydrate is the major substrate for respiration • Soluble carbohydrates exist – so they can easily be transported • Insoluble carbohydrates exist – so they can be easily stored

  8. Overview • Four stages:- 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Hydrogen / electron carrier system

  9. GLYCOLYSIS • Occurs in cytoplasm • Starts with Glucose • 6 carbon compound

  10. GLYCOLYSIS • Ends with Pyruvate • 3 carbon compound

  11. Glucose to TP • 2 molecules of ATP are invested

  12. TP to Pyruvate • Triose phosphate is converted to pyruvate (there are a number of intermediate stages)

  13. Energy is recovered… • ATP is made • Hydrogen is released and NAD is reduced

  14. Over all… • Net production of 2 ATP molecules from each molecule of glucose and 2 reduced NAD molecules

  15. Pyruvate moves into the mitochondria

  16. Precisely… • Into the matrix

  17. LINK REACTION • Pyruvate is converted into acetyl coenzyme A

  18. Pyruvate 3 carbon compound • Acetyl coenzyme A 2 carbon compound

  19. Oxidative … but no oxygen is involved • Hydrogen is removed • Combines with NAD • Producing reduced NAD

  20. KREBS CYCLE • Acetyl Co A (2 carbon compound) • Combines with a 4 carbon compound • Producing a 6 carbon compound

  21. In a number of steps… • 6 carbon compound breaks down to form the same 4 carbon compound that combined with acetyl co A Hence the Krebs CYCLE

  22. What is released? • Carbon – in the form of carbon dioxide • Hydrogen – combining with NAD and another coenzyme, FAD to form reduced NAD and reduced FAD

  23. Anything else? • There is enough energy released in one of the steps to join ADP and Phosphate to make ATP

  24. ELECTRON / HYDROGEN CARRIER SYSTEM • Carriers are in the inner membrane Cristae

  25. Hydrogen atoms • From hydrogen carriers – reduced NAD and reduced FAD • Accepted by the carriers in the membrane

  26. Hydrogen atoms break down to electrons and hydrogen ions (protons) • Protons build up between the two membranes of the mitochondria

  27. Protons move back into the matrix • Through an enzyme – ATP synthetase • ADP and phosphate join forming ATP

  28. The protons rejoin with electrons and oxygen to form water

  29. Oxidative phosphorylation • Phosphate is added to ADP – phosphorylation • The energy for the process is the result of the removal of hydrogen – oxidation

  30. Role of oxygen • Oxygen is the terminal electron acceptor in the electron carrier system

  31. ‘Oxidation’ • Oxidation occurs more than once in respiration BUT • In glycolysis • the link reaction • Krebs cycle It is the removal of hydrogen

  32. ‘Oxidation’ • Only in the electron carrier system is oxygen needed

  33. Aerobic and anaerobic respiration

  34. Fermentation • Anaerobic respiration • Occurs when oxygen is limited

  35. NAD is oxidised • Hydrogen combines with pyruvate • Forming :- lactate in animals ethanol in plants / fungi

  36. Glycolysis can continue… • Producing some ATP • Forming 2 ATP per glucose molecule • Compared with 38 ATP per glucose molecule with aerobic respiration

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