Biochemistry

Leslie Pugh

Biochemistry

CHEM 301

Biochemistry:

Glycolysis, The Krebs Cycle, The electron transport chain, Oxidative Phosphorylation

Metabolism is the set of chemical processes that occur in a cell, which enable it to keep living growing and dividing. Metabolic processes collectively are the sum of all chemical changes occurring in a cell, a tissue, or the body. Metabolic reactions are usually classified as either catabolic, obtaining its energy from nutrients, while breaking large complex molecules into simpler ones, usually releasing energy, or anabolic, assembling complex molecules from simpler ones, producing new cell components that require the input of energy. The energy for anabolic reactions is provided by catabolic reaction and is stored in cells as ATP. Nearly all organisms rely on the breakdown of glucose to provide energy to their cells. The metabolic pathways that are the focus of this paper are Glycolysis, which focuses on glucose oxidation in order to obtain ATP, Krebs’ cycle or acetyl-CoA oxidation in order to obtain GTP, Oxidative Phosphorylation which is the disposal of the electrons released by glycolysis and the Krebs’ cycle, and the Electron transport chain where energy rich molecuses are metabolized by a series of oxidation reactions yielding CO2 and H2O. In the presence of oxygen, aerobic metabolism includes the glycolysis, the Krebs’ cycle, and the electron transport chain resulting in an energy gain of 38 ATP per glucose molecule.

Glycolysis

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In glycolysis the six-carbon sugar glucose is oxidized and split in two halves, to create two molecules of pyruvate from each molecule of glucose. The cell is also able to take a small amount of ATP – 2 molecules from each glucose molecule. The pyruvate produced from each glucose molecule has one of three fates; either become pyruvate dehydrogenase, pyruvate carboxylase, ethanol or lactate dehydrogenase. In the presence of oxygen, the pyruvate...