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

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

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

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

18. Pyruvate moves into the mitochondria

19. Precisely… Into the matrix

20. LINK REACTION Pyruvate is converted into acetyl coenzyme A

21. Pyruvate 3 carbon compound Acetyl coenzyme A 2 carbon compound

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

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

24. 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

25. 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

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

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

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

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

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

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

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

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

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

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

36. Aerobic and anaerobic respiration

38. Fermentation Anaerobic respiration Occurs when oxygen is limited

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

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