13: Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway
- Page ID
- 15010
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- 13.1: Glycolysis
- In this section, we will provide you with a historical overview of glycolysis and introduce you to the 10 enzymatic reactions in the pathway. Our main goal is to understand how the oxidation of our major food molecules, sugars in the case of glycolysis, can lead to ATP synthesis.
- 13.2: Fates of Pyruvate under Anaerobic Conditions- Fermentation
- Fermentation is a process in which a fuel molecule is broken down in an anaerobically (or without oxygen), to produce energy. One of the most notable pathways that can utilize fermentation is glycolysis, which we have just described. During glycolysis, glucose is converted to pyruvate, yielding a total of 2 ATP energy rich molecules. This occurs in anoxic conditions (or without the requirement of oxygen).
- 13.3: Gluconeogenesis
- Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids. It is one of the two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low (hypoglycemia). The other means of maintaining blood glucose levels is through the degradation of glycogen (glycogenolysis).
- 13.4: Pentose Phosphate Pathway of Glucose Oxidation
- The pentose phosphate pathway (PPP), also known as the pentose phosphate shunt, is an important part of glucose metabolism. The PPP branches after the first step of glycolysis and consumes the intermediate glucose 6-phosphate (G6P) to generate fructose 6-phosphate (F6P) and glyceraldehyde 3-phosphate (G3P) through the oxidative and non-oxidative branches of the PPP.
Thumbnail: Due to its role in the pentose phosphate pathway and the Calvin cycle, D-Ribose-5-phosphate isomerase is highly conserved in most organisms, such as bacteria, plants, and animals. It plays an essential role in the metabolism of plants and animals, as it is involved in the Calvin cycle which takes place in plants, and the pentose phosphate pathway which takes place in plants as well as animals. (CC BY-SA 4.0; Ishikawa, K., Matsui, I., Payan, F., Cambillau, C., Ishida, H. et al. via Wikipedia)