mitochondria
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Mitochondria
(h) explain, with the aid of diagrams and electron micrographs, how the structure of mitochondria
enables them to carry out their functions;
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On your diagram, can you label....
• Inner and outer phospholipid membrane• The envelope• Cristae• Intermembrane space• Matrix• Stalked particles (ATP synthase)
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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)
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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
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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
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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
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Krebs Cycle
e-e-
e-e-
H+H+
H+H+H+H+
H+H+
Cyt Ce-e-
H+H+H+H+O2 H+H+H+H+H2O
ADP ATP
Cyt C
e- Q
H+`H+H+`H+
NADHNADH
NAD+NAD+
H+H+H+ H+ H+H+
H+
H+ H+ H+H+
H+
Cyt C
H+` H+`
e-
e-e-
IN
OUT
Animated by Peter RabinovitchBackground after Mandavilli et al, Mutation Research 509 (2002) 127–151
Mitochondrial Electron Transport Chain
2OH-2OH- OH-OH-
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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
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P86-87 Structure of ATP Synthase
• Remember protons flow DOWN the proton gradient NOT along
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http://www.americanchildneurologyuae.com/files/neurological-diseases/NEUROMETABOLIC/Mitochondrial-DO-Nature%202012%5b1%5d.pdf