| Oxidative phosphorylation | - The last stage of aerobic respiration
- Inner mitochondrial membrane
- Produces many molecules of ATP + produces H20 from O2 |
| Reactants | - NADH
- FADH2 |
| Products | - H20
- Energy
- ATP |
| The current model for oxidative phosphorylation | - Chemiosmotic theory |
| Chemiosmotic theory | - Energy from electrons passed through the ETC is used to pump H ions up their con. g. into the intermembrane space
- The Hs are then allowed to flow by facilitated diffusion through ATP synthase into the matrix
- Energy of the H2 flowing down their con. g. is harnessed resulting in the conversion of ADP into ATP by ATP synthase |
| The electron transport chain (ETC) | - Made up of a series of membrane proteins/electron carriers
- Positioned close together which allows the electrons to pass from carrier to carrier
- Inner membrane of the mitochondria is impermeable to H ions so these electron carriers are required to pump H across the membrane to establish the con. g. |
| An outline of oxidative phosphorylation (1) | - H2 is donated by NADH + FADH2 from the KC
- H2 split into protons (H+ ions) + electrons
- Electrons enter the ETC in a series of oxidation-reduction reactions |
| An outline of oxidative phosphorylation (2) | - Energy from electrons passed through the ETC is used to pump H ions up their con. g. into the intermembrane space
- A con. g. of protons is established between the intermembrane space and the matrix |
| An outline of oxidative phosphorylation (3) | - The Hs are then allowed to flow by facilitated diffusion through ATP synthase into the matrix
- Energy of the H2 flowing down their con. g. is harnessed resulting in the conversion of ADP into ATP by ATP synthase
- O2 acts as the 'final electron acceptor' + combines with protons and electrons at the end of the ETC to form H2O |
| Products from one Krebs cycle and where it goes | - 1 coenzyme A, reduced in the next link reaction
- Oxaloacetate, regenerated for use in the next Krebs cycle
- 2 CO2, released as a waste product
- 1 ATP, used for energy
- 3 reduced NAD, to oxidative phosphorylation
- 1 reduced FAD, to oxidative phosphorylation |
| Why is oxygen so important for aerobic respiration | - Final electron acceptor
- Without O2 ETC can't continue coz electrons have nowhere to go
- Without O2 accepting e-s + Hs, NADH2 + FADH2 cannot be oxidised to NAD and FAD
- So they can’t be used in further hydrogen transport |
| ATP production can be affected by mitochondria diseases | - Affect how proteins involved in OP or KC function, reducing ATP production
- This may cause anaerobic respiration to increase, to try and make up some of the ATP shortage
- This results in lots of lactate being produced, causes muscle fatigue + weakness
- Some lactate will also diffuse into the bloodstream, leading to high lactate concentrations in the blood |
| Releasing energy in stages | - The more energy that is released in a single step, the more of it is released as heat, less available for more useful purposes
- So, electrons carried by NAD + FAD are not transferred in one explosive step
- Instead passed along a series of electron transfer carrier molecules, each of which is at a slightly lower energy level
- The electrons move down an energy gradient
- Which allows their energy to be released gradually + more usefully |
| Alternative respiratory substrates | - Sugars are not the only substrates which can be oxidised by cells to release energy
- Both lipids + proteins may be used as respiratory substrates, without first being converted to carbohydrate |
| Respiration of lipids | - Trigs are hydrolysed to fatty acids + glycerol
- Glycerol is converted to triose phosphate
- Fatty acids hydrolyses into 2C fragments which are converted to acetylcoA
- Enter KC
- Energy yield is more that that of glucose respiration
- As trigs have more Hs than glucose, thus it carries more electrons, so more energy |
| Respiration of protein | - Hydrolysed into amino acids
- Have amino acid groups removed (deamination)
- 3C compounds converted to pyruvate
- 4 + 5C compounds converted to intermediates in KC |
