User:Atcovi/Science/Cellular Respiration/Glycolysis

The first step, which occurs in the cytoplasm, is called glycolysis. Literally meaning "breaking down glucose", glycolysis is an anaerobic process which uses two ATP in order to break down glucose into two simpler three carbon chains, known as pyruvic acid or "pyruvate".

6-carbon molecule glucose is phosphorylated with the help of ATP (this is known as the "investment phase"), which is followed by the enzyme, phosphoglucose isomerase (GPI), facilitating an equilibrium (can go both ways) enzyme-catalyzed reaction, where glucose 6-phosphate is changed to its isomer: fructose 6-phosphate. GPI helps the reaction go from one isomer of a molecule to another isomer of a molecule.

Another ATP-facilitated powerful reaction (still in the investment phase), by the name of phosphofructokinase, occurs. In this reaction, a phosphate group is attached to the fructose 6-phosphate molecule from the previous reactions. Magnesium cofactor, once again, helps stabilize a couple of the negative charges that are with the phosphate groups.

After these reactions: more reactions! An enzyme, known as fructose-bisphosphate aldolase, breaks down glucose. Aldolase enzymes facilitate carbon-carbon bond forming aldol reactions. The aldol reactions here break up the glucose into two three-carbon chains. These two three-carbon chains can be converted between each other with the help of another isomerase (in this case: triosephosphate isomerase).

An enzyme known as dehydrogenase facilitates the reduction of NAD+ into NADH (or it can be the other way around), which can be used in the electron transport chain (ETC). Also, a phosphate group is added to our glyceraldehyde 3-phosphate. This is followed up by a phosphate group removed from glyceraldehyde 3-phosphate, and in the process, produces ATP.

Afterwards, a mutase, known as phosphoglycerate mutase, moves one of the phosphate groups from one carbon to another carbon in the molecule.

After a reaction with an enolase, pyruvate kinase dephospholyrates our moving molecule, which results in our ending product: pyruvic acid.