4 stages: Glycolysis, Link
Reaction, Krebs Cycle &
Electron Transport Chain
1: GLYCOLYSIS
Occurs in the cytoplasm
Break down of Glucose
6C into 2 x Pyruvate 3C
1. Phosphorylation of Glucose
Glucose + 2 Pi from hydrolysis of
ATP gives energy (Lower AE for next
reactions)
2. Splitting of phosphorylated Glucose.
1 x Glucose (6C) ---> 2 x Triose Phosphate molecules (3C)
3. Oxidation (H loss) of
Triose Phosphate
NAD + H ---> Reduced NAD
4. 2 x ATP Produced ( Direct Substrate Level
Phosphorylation).
Enzymes control reaction to 2 x Triose Phosphate ---> 2 x Pyruvate (3C)
Pi + ADP ---> 4 x ATP However, 2 x ATP hydrolysed at start, so NET ATP = 2.
(+ 2 x Pyruvate & 2 x Reduced NAD)
Does not require oxygen
2: LINK REACTION
Occurs in the mitochondria.
Oxidation (H loss) of Pyruvate
from Glycolysis.
2 x Pyruvate actively transported from
cytoplasm to mitochondria.
4: ELECTRON TRANSPORT CHAIN
Occurs on the cristae using enzymes on
the membrane to synthesise ATP.
The H on the reduced coenzymes loss the eletrons; it is these that are
transported along the ETC.
1: Coenzymes Reduced NAD & FAD are OXIDISED (loss) and
releases electrons and H to create a proton gradient.
2: Electron is passed along protein carriers, losing energy
as it goes.
3: Series of Oxidation and Reduction reactions. OXYGEN is the FINAL
RECEPTOR and combines with H ---> WATER.
4: Electron energy is now stored in the proton gradient. This energy
synthesises ATP (INDIRECT OXIDATIVE PHOSPHORYLATION) + ATP
synthase on the stalked particles..
3: KREBS CYCLE
Occurs in the matrix of the mitochondria.
Break down of Acetylcoenzyme
(2C + 4C molecule) into smaller
(4C) molecule.
Produces 1 x ATP + Reduced FAD & NAD + 2 x Carbon Dioxide.
Anaerobic
In Animals. NO Carbon Dioxide is released.
However, In plants, Carbon Dioxide is released!
If no Oxygen is available, the H from reduced NAD (glycolysis) + pyruvate ---> lactate.