Expert: Dana Krempels, Ph.D. - 9/4/2007

Question
What is the differences between glycolysis,Kreb's Cycle and electron transport chain?

Answer
Dear Dr. Hamdan,

The three processes you name are three parts of the complete chain of events required for a cell to harvest energy from stored carbohydrate.  In order, they are (1) glycolysis, (2) pyruvate activation, (3) Krebs cycle, and (4) electron transport chain.

Glycolysis is a term meaning "splitting of glycogen," which is the reaction that precedes the Krebs Cycle.  Glycolysis results in the splitting of glycogen into glucose, and then each glucose molecule into two molecules of pyruvate, the raw material of the Krebs Cycle.

The Krebs Cycle follows glycolysis, and is the series of about 17 chemical reactions by which a cell harvests the energy in the pyruvate molecules.  The end products of one cycle are one GTP, three NADH, one FADH2, and two CO2 molecules.

Finally, the GTP, NADH and FADH2 pass through the electron transport chain, which associates electron carriers (such as NAD+ and FADH2) and mediating biochemical reactions (via enzymatic action of plasma-membrane bound, proteins) that produce adenosine triphosphate (ATP), which is the "energy currency" of the cell.

Hope that helps!  :)

Dana