Cytoplasm glycolysis

Fig. 6a-c Imaging NAD(P)H in cultured pancreatic islet beta cells at a basal 1 mM glucose and b after 20 mM glucose stimulation, c The cytoplasmic and mitochondrial NAD(P)H can be quantified representing cytoplasmic glycolysis metabolism and mitochondrial citric acid cycle metabolism, respectively. (Reproduced from Patterson et al. 2000, copyright 2000, National Academy of Sciences, USA)... 

Only cytoplasmic glycolysis is considered here nuclear glycolysis is reviewed in another section. 

Pyruvate produced by glycolysis is a significant source of acetyl-CoA for the TCA cycle. Because, in eukaryotic ceils, glycolysis occurs in the cytoplasm, whereas the TCA cycle reactions and ail subsequent steps of aerobic metabolism take place in the mitochondria, pyruvate must first enter the mitochondria to enter the TCA cycle. The oxidative decarboxylation of pyruvate to acetyl-CoA,... 

In plant plastids, GGPP is formed from products of glycolysis and is eight enzymatic steps away from central glucose metabolism. The MEP pathway (reviewed in recent literature - ) operates in plastids in plants and is a preferred source (non-mevalonate) of phosphate-activated prenyl units (IPPs) for plastid iso-prenoid accumulation, such as the phytol tail of chlorophyll, the backbones of carotenoids, and the cores of monoterpenes such as menthol, hnalool, and iridoids, diterpenes such as taxadiene, and the side chains of bioactive prenylated terpenophe-nolics such as humulone, lupulone, and xanthohumol. The mevalonic pathway to IPP that operates in the cytoplasm is the source of the carbon chains in isoprenes such as the polyisoprene, rubber, and the sesquiterpenes such as caryophyllene. 

Note that the strength of the correlations is increased by the fact that the citric acid pathway is today isolated in mitochondria derived from a distinct early life form and linked to both aspartate and glutamate, in which A and C are dominant amino-acid carriers, while glycolysis and the pentose shunt are cytoplasmic, where U and G are more dominant amino-acid carriers. 

The polymorph is the dominant white cell in the blood stream and, like the macrophage, shares a common hemopoietic stem cell precursor with the other formed elements of the blood. It has no mitochondria, but utilizes its abundant cytoplasmic glycogen stores for its energy requirements thus, glycolysis enables these cells to function under anaerobic conditions such as those in an inflammatory focus. It is a nondividing, short-lived cell with a segmented nucleus. 

Glycolysis is a catabolic pathway in the cytoplasm that is found in almost all organisms— irrespective of whether they live aerobically or anaerobically. The balance of glycolysis is simple glucose is broken down into two molecules of pyruvate, and in addition two molecules of ATP and two of NADH+H"" are formed. 

The pentose phosphate pathway (PPP, also known as the hexose monophosphate pathway) is an oxidative metabolic pathway located in the cytoplasm, which, like glycolysis, starts from glucose 6-phosphate. It supplies two important precursors for anabolic pathways NADPH+H+, which is required for the biosynthesis of fatty acids and isopren-oids, for example (see p. 168), and ribose 5-phosphate, a precursor in nucleotide biosynthesis (see p. 188). 

In the cytoplasm, oxaloacetate is reformed and then converted into phospho-enol pyruvate by a GTP-dependent PEP car-bo)Q/kinase. The subsequent steps up to fructose 1,6-bisphosphate represent the reverse of the corresponding reactions involved in glycolysis. One additional ATP per C3 fragment is used for the synthesis of 1,3-bisphos-phoglycerate. 

In eukaryotes, the cytoplasm, representing slightly more than 50% of the cell volume, is the most important cellular compartment. It is the central reaction space of the cell. This is where many important pathways of the intermediary metabolism take place—e.g., glycolysis, the pentose phosphate pathway, the majority of gluconeogenesis, and fatty acid synthesis. Protein biosynthesis (translation see p. 250) also takes place in the cytoplasm. By contrast, fatty acid degradation, the tricarboxylic acid cycle, and oxidative phosphorylation are located in the mitochondria (see p. 210). 

Two systems known as shuttles are available to allow the import of reducing equivalents that arise from glycolysis in the cytoplasm in the form of NADH+HT There is no transporter in the inner membrane for NADH+H itself... 

The tightly regulated pathway specifying aromatic amino acid biosynthesis within the plastid compartment implies maintenance of an amino acid pool to mediate regulation. Thus, we have concluded that loss to the cytoplasm of aromatic amino acids synthesized in the chloroplast compartment is unlikely (13). Yet a source of aromatic amino acids is needed in the cytosol to support protein synthesis. Furthermore, since the enzyme systems of the general phenylpropanoid pathway and its specialized branches of secondary metabolism are located in the cytosol (17), aromatic amino acids (especially L-phenylalanine) are also required in the cytosol as initial substrates for secondary metabolism. The simplest possibility would be that a second, complete pathway of aromatic amino acid biosynthesis exists in the cytosol. Ample precedent has been established for duplicate, major biochemical pathways (glycolysis and oxidative pentose phosphate cycle) of higher plants that are separated from one another in the plastid and cytosolic compartments (18). Evidence to support the hypothesis for a cytosolic pathway (1,13) and the various approaches underway to prove or disprove the dual-pathway hypothesis are summarized in this paper. 

Pyruvate derived from glycolysis or from catabolism of certain amino acids is transported from the cytoplasm into the mitochondrial matrix. 

Mitochondria are not permeable to NADH. However, reactions of glycolysis and other dehydrogenations in the cytoplasm quickly reduce available NAD+ to NADH. For aerobic metabolism to occur, the "reducing equivalents" from the NADH must be transferred into the mitochondria. Fungi and green plants have solved... 

Glycolysis is a set of reactions that take place in the cytoplasm of prokaryotes and eukaryotes. The roles of glycolysis are to produce energy (both directly and by supplying substrate for the citric acid cycle and oxidative phosphorylation) and to produce intermediates for biosynthetic pathways. 

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

In eukaryotes, electron transport and oxidative phosphorylation occur in the inner membrane of mitochondria. These processes re-oxidize the NADH and FADH2 that arise from the citric acid cycle (located in the mitochondrial matrix Topic L2), glycolysis (located in the cytoplasm Topic J3) and fatty acid oxidation (located in the mitochondrial matrix Topic K2) and trap the energy released as ATP. Oxidative phosphorylation is by far the major source of ATP in the cell. In prokaryotes, the components of electron transport and oxidative phosphorylation are located in the plasma membrane (see Topic Al). 

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