Anaerobic metabolism glycolysis

Under anaerobic conditions, glycolysis results in a net synthesis of only two ATP molecules for each molecule of glucose metabolized (Table 6-1). 

Lactate is a useful parameter of cerebral metabolism. The level of lactate is not influenced by plasmatic concentration. Lactate is produced only in small amounts in CSF in the case of anaerobic glycolysis. Under physiological conditions, lactate penetrates the blood-brain barrier in very low concentrations. In bacterial meningitis, the main source of lactate is brain tissue. Different mechanisms are included in the production of lactate first, brain edema with reduction of cerebral blood flow, ischemia, and (consequently) anaerobic metabolism then, production... 

Glycolysis involves the breakdown of energy-storage polysaccharides or glucose to the 3-carbon acid, pyruvate. Its function is to produce energy in the form of ATP and 3-carbon intermediates for further metabolism. Glycolysis occurs under both aerobic and anaerobic conditions. 

The Embden-Mayerhof pathway of glycolysis, also known as anaerobic metabolism, is perhaps an early function coupled directly to photosynthesis, which requires chloroplasts for the recovery of reduction potential from the photolysis of water.15 Chloroplasts were perhaps finished even earlier than any other structure but certainly 3.5 billion years ago lest blue-green algae could not have been blue- green ... 

In fast white fibers, glycolysis catabolizes glucose. The relative lack of mitochondria in these fibers causes the white appearance. The rapid breakdown of glucose by anaerobic metabolism means that ATP is made rapidly. These muscles are used in rapid, short-duration movement and exhibit a fast twitch when electrically stimulated. The flight muscles of birds are of this type—remember that you find the white meat of a chicken on the breast. 

The properties of anaerobic metabolism are also strongly determined by the isozyme arrays present at each step in the anaerobic glycolysis of vertebrate muscle, so the question arises as to whether or not training can lead to adjustments... 

From the above discussion, it is evident that anaerobic metabolism in many animals can be far more versatile than commonly observed in higher vertebrates and that this raises the possibility of utilizing energetically more efficient fermentations. Estimating how much more efficient than anaerobic glycolysis is complicated by the observation that different combinations of pathways can be utilized at different times in anoxia. 

The regulation of these two means of ATP production is very different. Under aerobic conditions (see answer to Problem 9), glycolysis is inhibited by the relatively high [ATP], as acetyl-CoA units derived from fat feed into the citric acid cycle and ATP is produced by oxidative phosphorylation. Under anaerobic conditions, glycolysis is stimulated and metabolism of fats does not occur at an appreciable rate because [citrate] and [acetyl-CoA] are low and 02 (the final acceptor of electrons in oxidative phosphorylation) is absent. 

Glycolysis produces energy. Michael Johnson sprints to another victory in the 200-meter semifinals of the Olympics. Johnson, like anyone who sprints, requires a source of energy that can be rapidly accessed. The anaerobic metabolism of glucose the process of glycolysis provides such a source of energy for short, intense bouts of exercise. [Simon Bruty/ Allsport.]... 

Lactic acidosis is one of the most common canses of high SAG metabolic acidosis. Lactic acid is the end prodnct of anaerobic metabolism of glucose (glycolysis). In normal individnals, lactic acid derived from pyruvate enters the circulation in small amonnts and is promptly removed by the liver. In the liver, and to a lesser extent in the kidney, lactic acid is reoxidized to pyruvic acid, which is then metabolized to CO2 and H2O. The normal plasma lactate concentration in healthy subjects is approximately 1 rnEq/L. " The diagnosis of lactic acidosis should be considered in aU patients with metabolic acidosis... 

What are the possible fates of pyruvate in glycolysis In glycolysis, one molecule of glucose gives rise, after a long series of reactions, to two molecules of pyruvate. Along the way, two net molecules of ATP and NADH are produced. In aerobic metabolism, pyruvate is further oxidized to carbon dioxide and water. In anaerobic metabolism, the product is lactate or, in organisms capable of alcoholic fermentation, it is ethanol. 

Aerobic metabolism is a highly efficient way for an organism to extract energy from nutrients. In eukaryotic cells, the aerobic processes (including conversion of pyruvate to acetyl-GoA, the citric acid cycle, and electron transport) all occur in the mitochondria, while the anaerobic process, glycolysis, takes place outside the mitochondria in the cytosol. We have not yet seen any reactions in which oxygen plays a part, but in this chapter we shall discuss the role of oxygen in metabolism as the final acceptor of electrons in the electron transport chain. The reactions of the electron transport chain take place in the inner mitochondrial membrane. 

Anaerobic glycolysis is the principal pathway for the anaerobic metabolism of glucose. The pentose phosphate pathway can also be considered. Aerobic glycolysis and the citric acid cycle are responsible for the aerobic metabolism of glucose. 

The reducing equivalents from glycolysis, the Krebs cycle, or other catabolic pathways are carried by coenzymes, particularly NAD, and to some extent FAD. The coenzymes then need to be reoxidized so that the coenzymes can be used again. In anaerobic metabolism, the terminal electron acceptor is a carbon-containing compound, such as pyruvate or acetaldehyde. The Krebs cycle releases carbon as CO2, which can be reduced, but only by a reductant stronger than NADH. In aerobic metabolism, the terminal electron acceptor is oxygen, O2, which is reduced to water ... 

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