The overall equation for cellular respiration is:
C6H12O6 + 6O2 + 6H2O → 12H2O + 6 CO2
glucose + oxygen +water --> water +carbon dioxide.
There are three main goals which cellular respiration accomplishes and they are:
1. breaking the bonds of the six carbon glucose molecule
2. removing the hydrogen atom electrons from the glucose molecule to oxygen
3. and creating a ATP.
There are 4 main processes in cellular respiration.
1. Glycolysis- a 10 step process which means splitting sugars
2. Link reaction (Pyruvate oxidation) - pyruvate is oxidized to acetyl-CoA and CO2
3. The Krebs Cycle (citric acid cycle)- a series of reaction that transfers energy from organic molecules to ATP, NADH, and FADH2
4. Electron transport chain and chemiosmosis- a series of membrane associated protein complexes and complexes that transfer energy to an electron gradient
GLYCOLYSIS
Glycolysis occurs in the cytoplasm. The break down of the sugar requires 2 ATP molecules in order for the molecule to be energized. One the ATP has been added the glucose splits into two and becomes a 3C molecule. Hydrogen ions and electrons are taken from each of the 3C to create NADH from NAD+. The 3C molecule has been arranged into pyruvate where 4 ATP molecules are made.
LINK REACTION
Pyruvate molecule that was created in glycolysis then moves on to the Link Reaction. This is where the CO2 molecule is removed. The remaining two carbons are then oxidized by NAD+, where NAD+ gains 2 hydrogen atoms from the sugar and becomes acetic acid. This is a redox reaction. The final step for the Link reaction is when an enzyme called coenzymeA is attached to the acetate group and creating acetyl-CoA
KREB'S CYCLE
The acteyl CoA that was produced in the Link reaction has moved on into the Krebs Cycle. The Acteyl- CoA joins with oxaloacetic acid which creates a 6C molecule which is called citric acid, hence another name for this cycle is the citric acid cycle. Citric acid is oxidized therefore releasing CO2, H+ and and electron. The free electron that has been oxidized is reduced to the energy carries of NAD+ to NADH2 and from FAD+ to FADH2. The cycle continues to oxidizing carbons creating more CO2, NADH2, FADH2 and ATP. From the cycle CO2 is produced which exits the cell. NADH2 and FADH2 now migrate to the Electron Transport Chain
ELECTRON TRANSPORT CHAIN
The electron transport chain is found in the inner mitochondrial membrane or the cristae. The ETC contains 4 protein based chambers which work in a sequence to move H+ ions from the matrix across the inner membrane using proton pumps. Once this occurs a H+ concentration gradient occurs between the inner and the outer mitochondrial membrane. The gradient caused the production of ATP by chemosmosis. The energized electrons and the hydrogen ions from the NADH2 and FADH2 are transferred to oxygen to produce water which is a redox reaction \.
