The process by which your cells transfer the energy in organic compounds (glucose, starch, carbohydrates) to ATP, the byproduct of this reaction is water and carbon dioxide. It occurs in the cell's cytosol (cytoplasm) and the cell's mitochondria, the energy producer or "powerhouse" of the cell.
2. Krebs Cycle
3. Electron Transport Chain (oxidative phosphorylation)
1. Glycolysis (anaerobic: does not require oxygen)
2. Krebs Cycle (also known as the CITRIC ACID CYCLE) (aerobic--requires oxygen)
3. The Electron Transport Chain (also known as oxidative phosphorylation)
Produces the energy that drives the synthesis of ATP in oxidative phosphorylation
Consists of molecules (mostly proteins) that are embedded in the inner mitochondria
Cofactors are attached to these proteins. The cofactors are alternately reduced and oxidized as they accept and donate electrons
The initial electron acceptor in the chain is a flavoprotein (FMN) and it accepts an electron from NADH. The electron is then passed down a series of molecules to oxygen, which is the final electron acceptor. It is then combined with a couple of hydrogen ions, H+, to form water. The process will not function in the absence of oxygen.
FADH2 and NADH both donate electrons to the chain
The electron transport chain doesn't make any ATP itself, instead these reactions are coupled to others to produce ATP, a process called CHEMIOSMOSIS
of the mitochondrion
View both of these animations! They will totally help you understand!
Animation of Electron Transport Chain Another Animation of Electron Transport Chain
The NET RESULTS of the Aerobic Respiration
Each NADH produces 3 ATP
Remember 8 NADH were created in the Krebs Cycle and 2 in Glycolysis
Each FADH2 produces 2 ATP (since FADH2 enters the ETC at a lower step)
Remember 2 FADH2 were created in the Krebs Cycle
Do the math: 34 ATP produced in the ETC + 2 from glycolysis + 2 from Krebs = 38 total ATP from each glucose
However....In some cells 2 ATP are used to move NADH into the mitochondria from the cytoplasm. Therefore, a grand total of 36 ATP produced from each glucose molecule
In the absence of oxygen (remember that oxygen is the final electron acceptor) the cell goes through a process called FERMENTATION
Fermentation takes place under anaerobic conditions (no oxygen present). There are two types of fermentation, alcoholic fermentation and lactic acid fermentation.
Alcoholic Fermentation: occurs in yeasts, fungi and some bacteria.
Pyruvate (C3) ® Acetaldehyde (C2) + CO2
Acetaldehyde (C2) + NADH ® 2 Ethanol (C2) + NAD+
Lactic Acid Fermentation: occurs in some bacteria and oxygen deprived human muscle cells where lactate is produced as a waste product. Muscle cramps are caused by increased acidity caused by the lactate build up.
NADH + Pyruvate (C3) ® Lactic Acid (C3) + NAD+