Glycolysis overview

Next step of glycolysis Enzymes of glycolysis Glycolysis overview... 

We will return to an overview of anabolic pathways shortly, but first we want to examine in more detail the two important catabolic pathways, glycolysis and the tricarboxylic acid cycle. 

During ripening, three primary biochemical events occur, glycolysis, lipolysis and proteolysis. The products of these primary reactions undergo numerous modifications and interactions. The primary reactions are fairly well characterized but the secondary changes in most varieties are more or less unknown. An overview of the principal biochemical changes follows. 

FIGURE 22-9 Overview of amino acid biosynthesis. The carbon skeleton precursors derive from three sources glycolysis (pink), the citric acid cycle (blue), and the pentose phosphate pathway (purple). 

Systems of biochemical reactions like glycolysis, the citric acid cycle, and larger and smaller sequential and cyclic sets of enzyme-catalyzed reactions present challenges to make calculations and to obtain an overview. The calculations of equilibrium compositions for these systems of reactions are different from equilibrium calculations on chemical reactions because additional constraints, which arise from the enzyme mechanisms, must be taken into account. These additional constraints are taken into account when the stoichiometric number matrix is used in the equilibrium calculation via the program equcalcrx, but they must be explicitly written out when the conservation matrix is used with the program equcalcc. The stoichiometric number matrix for a system of reactions can also be used to calculate net reactions and pathways. 

Overview Glycolysis is a series of reactions (Fig. 1) that takes place in the cytoplasm of... 

Chemically induced cardiac failure has been the subject of a number of works. Balazs and Ferrans (1978), Baskin (1991), and Acosta (2001) give an overview of the subject. Hypoxia is one of the effects of the decreased availability of ATP which depresses contraction in the muscle. The energy that is supplied by the phosphate bonds is possible only as long as aerobic glycolysis and oxidative phosphorylation are maintained. Under anoxic conditions, this is no longer possible and with the adrenergic stimulus continuing, calcium accumulation in the mitochondria leads to... 

Despite the enormous variety of SM, the number of corresponding basic bios)mthetic pathways is restricted and distinct. Precursors usually derive from basic metabolic pathways, such as glycolysis, the Krebs cycle or the shikimate pathway A schematic overview is presented in Figs 1.2 and 1.3. Plausible hypotheses for the bios)mthesis of most SM have been published (for overviews see Bell and Charlwood, 1980 Conn, 1981 Mothes et al,... 

Conceptual Insights, Overview of Carbohydrate and Fatty Acid Metabolism. View this media module to gain a "bigger picture" understanding of the roles of the pentose phosphate pathway in the context of other metabolic pathways (glycolysis, citric acid cycle, glycogen and fatty acid metabolism). 

Figure 7-6. Overview of the synthesis of nonessential amino adds. Ten amino acids may be produced from glucose via intermediates of glycolysis or the TCA cycle. The eleventh amino acid, tyrosine, is synthesized by hydroxylation of the essential amino acid phenylalanine. TA = transamination GDH- glutamate dehydrogenase.

Pyruvate Idnase deficiency (OMIM 266200) is the most common cause of nonspherocytic hemolytic anemia due to defective glycolysis. The allelic frequency is estimated to be around 2%. The consequent lack of sufficient energy, which is required for normal functioning and cellular survival, shortens the life span of the mature PK-deficient erythrocyte. Consequently, PK-deficient patients display a phenotype of nonspherocytic hemolytic anemia albeit with variable clinical severity. The clinical symptoms vary from neonatal death to a well-compensated hemolytic anemia. Patients benefit in general from a splenectomy. Pyruvate kinase deficiency is transmitted as an autosomal recessive disease. To date, more than 130 mutations in PKLR have been reported to be associated with pyruvate kinase deficiency (see Figure 21-10 for overview see reference 221). Most (70%) of these mutations are missense mutations affecting conserved residues in structurally and functionally important domains of PK. Splice site mutations, a deletion. 

If the cell requires more NADPH than ribose molecules, it can channel the products of the nonoxidative phase of the pentose phosphate pathway into glycolysis. As this overview of the two pathways illustrates, excess ribose-5-phos-phate can be converted into the glycolytic intermediates fructose-6-phosphate and glyceraldehyde-3-phosphate. 

In the overview of glycolysis we noted that the pyruvate produced must be used up in some way so that the pathway will continue to produce ATP. Similarly, the NADH produced by glycolysis in step 6 (see Figure 21.8) must be reoxidized at a later time, or glycolysis will grind to a halt as the available NAD+ is used up. If the cell is functioning under aerobic conditions, NADH will be reoxidized, and pyruvate will be completely oxidized by aerobic respiration. Under anaerobic conditions, however, different types of fermentation reactions accomplish these purposes. Fermentations are catabolic reactions that occur with no net oxidation. Pyruvate or an organic compound produced from pyruvate is reduced as NADH is oxidized. We will examine two types of fermentation pathways in detail lactate fermentation and alcohol fermentation. 

Genetic Disorders of Glycolysis An Overview Reactions of Glycolysis Regulation of Glycolysis... 

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