Powerpoint Presentation: Respiration and the Electron Transport Chain
Introduction : Energy in Food
Photosynthesis and Respiration
The Respiratory Quotient and Respirometers
Topic Chapters Index
The Electron Transport Chain (ETC)
- Most ATP is manufactured by oxidative phosphorylation.
- A series of redox reactions using electron acceptor/donor molecules coupled to glycolysis and the Kreb's cycle.
- The electron acceptors/donors reduce (when receiving electrons) and oxidise (when losing electrons) one another along an
electrochemical gradient. Each molecule in the series has a lower
redox potential than the one before.
- Each redox reaction results in a release of energy.
- If this energy release is > 30.5 kJ mol-1 a mole of ATP can be synthesised from ADP by a coupled reaction.
- The first molecule in the series is NAD (or
FAD), a coenzyme of various dehydrogenase enzymes.
NADH + H+ (reduced)
- Next come a series of iron containing proteins called
- The last electron acceptor in the series is
- Electrons are produced by splitting hydrogen atoms taken from the food molecules (H H+ + e-) by dehydrogenases. Thus at the end of the ETC:
2H+ + 2e- + ½O2
The location of the ETC
The mitochondrial inner membrane of eukaryotes(the plasma membrane of prokaryotes).
Surface area increased by cristae. Density of cristae is proportional to activity of the cell. For example:
Liver cell 40 m2 g-1 mitochondria
Heart muscle 200 to 250 m2 g-1 mitochondria
The Mechanism: The Chemiosmotic Pump
The ETC creates a concentration gradient by pumping H+ out of the mitochondrial inner matrix. As these H+ diffuse back into the matrix across the inner membrane they drive ATP synthesis.
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