Mitochondria have an inner and outer membrane that form compartments. The inner membrane is folded into cristae which increases surface area and contains ATP synthase enzymes and electron carriers. The electron transport chain uses energy from electron flow along protein complexes to pump protons from the matrix to the intermembrane space, building a proton gradient. ATP synthase uses this proton gradient to phosphorylate ADP into ATP. The matrix contains enzymes for the link reaction and Krebs cycle that generate NADH used in the electron transport chain.

1. Mitochondria
(h) explain, with the aid of diagrams and electron
micrographs, how the structure of mitochondria
enables them to carry out their functions;

2. On your diagram, can you label....
•
•
•
•
•
•
Inner and outer phospholipid membrane
The envelope
Cristae
Intermembrane space
Matrix
Stalked particles (ATP synthase)

3. Stages of Respiration
1. Glycolysis (Cytoplasm)
2. Link Reaction (Mitochondrial Matrix)
3. Krebs Cycle (Mitochondrial Matrix)
4. Oxidative Phosphorylation (electron carriers,
oxygen and mitochondrial cristae)

6. Mitochondrial Structure and Function
– The Matrix
Link reaction and Krebs Cycle
• Enzymes are present to catalyse the above
reactions
• Coenzyme NAD is present
• Oxaloacetate present – accepts acetate from the
link reaction
• Mitochondrial DNA – codes for some of the
enzymes and proteins required
• Mitochondrial ribosomes – to assemble the
above proteins

7. Mitochondrial Structure and Function
– The Outer Membrane
The outer membrane contains proteins.
• Some of these proteins form channels or
carriers to allow the passage of molecules
such as pyruvate (from glycolysis)
• Enzymes are also present in the membrane

8. Mitochondrial Structure and Function
– The Inner Membrane
• Impermeable to most small ions including
protons (hydrogen ions). Has a different lipid
composition to the outer membrane.
• Is folded into cristae to give a large surface
area
• Has many ATP synthase enzymes and
electron carriers embedded in it. The
electron carriers are protein complexes
arranged in electron transport chains

9. Mitochondrial Electron Transport Chain
+
H+ H+
+H
+
HH
H+
OUT
Cyt C
e- e-
e-
IN
e- e-
Cyt C
e- e-
Q e- e-
H++ ++
H
2OH
H H-
O2 OHH++ 2O
H+H H
H+ -
H+`+` NAD+
H H+
ADP
NADH
ATP
Krebs
Cycle
Animated by Peter Rabinovitch
Background after Mandavilli et al, Mutation Research 509 (2002) 127–151

10. Electron transport chains
• Each electron carrier is an enzyme and has a
cofactor associated with it. Cofactors are haem
groups and contain an iron atom
• Iron atoms can become reduced to Fe2+ or
oxidised to Fe3+ by accepting and donating
electrons
• The carriers are oxidoreductase enzymes as they
are involed in oxidation and reduction reactions
• Some electron carriers also have a coenzyme that
pumps (using energy from the passage of
electrons) protons from the matrix to the
intermembrane space, building up a proton
gradient

11. P86-87 Structure of ATP Synthase
• Remember protons flow DOWN the proton
gradient NOT along

12. http://www.americanchildneurologyu
ae.com/files/neurologicaldiseases/NEUROMETABOLIC/Mitochon
drial-DONature%202012%5b1%5d.pdf