Cellular Catabolism

GlycolysisPacket #26Chapter #9

IntroductionGlycolysis is a stage common to all

organisms.The chain of reactions, that make up

glycolysis, convert each molecule of glucose into smaller molecules.Pyruvate

Although it is not necessary to know all of the intermediate compounds/enzymes, but an appreciation for the major features is required.

Introduction IIGlycolysis is derived from the Greek glykos,

meaning sugar, and lysis, meaning splitting.Glycolysis is the chain of reactions that

convert each molecule of glucose* into smaller pyruvate molecules.

During the chain of reactions, used in the making of pyruvate, two important molecules are produced.ATPNADH

Production of ATP During GlycolysisGlycolysis produces ATP

without the involvement of molecular oxygen.

The production of ATP, without the use of oxygen, is called substrate level phosphorylation.

During glycolysis, substrate level phosphorylation allows the net production of 2 ATP’s.Four ATP’s are produced

while two ATP’s are used. Yielding two net ATP’s

Substrate Level PhosphorylationAn enzyme, normally

a protein kinase, removes a phosphate from the substrate and adds it to ADP to form ATP.

Production of NADHDuring the production

of sugar intermediates, oxidation occurs when NAD+ removes electrons, via the H+

found on the original sugar (glucose) molecule, to make NADH.

During glycolysis, two NADH’s are produced per glucose molecule.

End Product of GlycolysisPyruvate At the end of the series of

reactions, the production of the three carbon molecule, pyruvate, is complete. Two pyruvates per glucose

molecule. Pyruvate, the three carbon

product resulting form the splitting of sugar, passes from the cytosol to the mitochondria where the molecule is converted into CO2 plus an acetyl group (contains two carbons—ACoA). This occurs immediately

following the ten steps of glycolysis.

Also formed is one NADH molecule. (per pyruvate)

Immediately Following GlycolysisPyruvate (3C) is

converted into an acetyl group (2C).

Acetyl group (2C) attaches to coenzyme A (CoA) to form acetyl CoA (ACoA).

ReviewGlycolysis is a series of 10 steps that occurs

inside the cytosol of the cell.Glucose (6C) is split into two parts that ultimately

result in the production of two pyruvates (3C.2 net ATP’s are produced per glucose molecule.2 NADH’s are produced per glucose molecule.Immediately following glycolysis, each pyruvate

(3C) is used to produce ACoA (2C) and one CO2.

Deeper Insight ISteps #1 – 3 is the

energy investment phase

Deeper Insight II• Steps #4 – 5 is the

cleavage of the six-carbon molecule to two three carbon sugars.• Glyceraldehyde 3-

phosphate

Deeper Insight IIISteps #5 – 10

The energy generation phase End product be

pyruvate.