glykoliseoksien

Glycolysis, also known as the glycolytic pathway, is a fundamental metabolic process that occurs in the cytoplasm of nearly all living organisms. It is the initial stage of cellular respiration, where one molecule of glucose, a six-carbon sugar, is broken down into two molecules of pyruvate, a three-carbon compound. This breakdown yields a net gain of two ATP molecules (adenosine triphosphate), the primary energy currency of the cell, and two molecules of NADH (nicotinamide adenine dinucleotide), an electron carrier.

The glycolytic pathway is a series of ten enzymatic reactions. It can be broadly divided into two phases: the energy investment phase and the energy payoff phase. In the energy investment phase, two ATP molecules are consumed to destabilize the glucose molecule, preparing it for cleavage. This results in the formation of two three-carbon sugar phosphates. The subsequent energy payoff phase involves the oxidation of these three-carbon molecules, leading to the production of four ATP molecules and two NADH molecules.

Glycolysis is an anaerobic process, meaning it does not require oxygen. This allows it to occur even in the absence of oxygen, providing a rapid source of energy for cells. The pyruvate produced during glycolysis can then enter various metabolic fates depending on the availability of oxygen. Under aerobic conditions, pyruvate is further processed through the citric acid cycle and oxidative phosphorylation, generating significantly more ATP. In anaerobic conditions, pyruvate is converted into lactate or ethanol through fermentation, regenerating NAD+ which is essential for glycolysis to continue. This ancient pathway is central to energy metabolism in both prokaryotic and eukaryotic cells.