Glycolysis


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The metabolic pathway of glycolysis converts glucose to pyruvate via a series of intermediate metabolites.    Each chemical modification is performed by a different enzyme.    Steps 1 and 3 consume ATP and    steps 7 and 10 produce ATP. Since steps 6–10 occur twice per glucose molecule, this leads to a net production of ATP.
Summary of aerobic respiration

Glycolysis is the metabolic pathway that converts glucose (C6H12O6) into pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH).[1] Glycolysis is a sequence of ten reactions catalyzed by enzymes.

Summary of the 10 reactions of the glycolysis pathway

The wide occurrence of glycolysis in other species indicates that it is an ancient metabolic pathway.[2] Indeed, the reactions that make up glycolysis and its parallel pathway, the pentose phosphate pathway, can occur in the oxygen-free conditions of the Archean oceans, also in the absence of enzymes, catalyzed by metal ions, meaning this is a plausible prebiotic pathway for abiogenesis.[3]

The most common type of glycolysis is the Embden–Meyerhof–Parnas (EMP) pathway, which was discovered by Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. Glycolysis also refers to other pathways, such as the Entner–Doudoroff pathway and various heterofermentative and homofermentative pathways. However, the discussion here will be limited to the Embden–Meyerhof–Parnas pathway.[4]

The glycolysis pathway can be separated into two phases:[5]

  1. Investment phase – wherein ATP is consumed
  2. Yield phase – wherein more ATP is produced than originally consumed
  1. ^ Alfarouk KO, Verduzco D, Rauch C, Muddathir AK, Adil HH, Elhassan GO, et al. (18 December 2014). "Glycolysis, tumor metabolism, cancer growth and dissemination. A new pH-based etiopathogenic perspective and therapeutic approach to an old cancer question". Oncoscience. 1 (12): 777–802. doi:10.18632/oncoscience.109. PMC 4303887. PMID 25621294.
  2. ^ Romano AH, Conway T (1996). "Evolution of carbohydrate metabolic pathways". Research in Microbiology. 147 (6–7): 448–455. doi:10.1016/0923-2508(96)83998-2. PMID 9084754.
  3. ^ Keller MA, Turchyn AV, Ralser M (April 2014). "Non-enzymatic glycolysis and pentose phosphate pathway-like reactions in a plausible Archean ocean". Molecular Systems Biology. 10 (4): 725. doi:10.1002/msb.20145228. PMC 4023395. PMID 24771084.
  4. ^ Kim BH, Gadd GM. (2011) Bacterial Physiology and Metabolism, 3rd edition.
  5. ^ Mehta S (20 September 2011). "Glycolysis – Animation and Notes". PharmaXchange.