how many atp molecules are obtained from glycolysis
Four molecules of ATP
983008
lactate. In aerobic conditions, the process converts one molecule of glucose into two molecules of pyruvate (pyruvic acid), generating energy in the form of two net molecules of ATP. Four molecules of ATP per glucose are actually produced, however, two are consumed as part of the preparatory phase. The initial phosphorylation of glucose is required to increase the reactivity (decrease its stability) in order for the molecule to be cleaved into two pyruvate molecules by the enzyme aldolase. During the pay-off phase of glycolysis, four phosphate groups are transferred to ADP by substrate-level phosphorylation to make four ATP, and two
Cellular respiration
983008
lactate. In aerobic conditions, the process converts one molecule of glucose into two molecules of pyruvate (pyruvic acid), generating energy in the form of two net molecules of ATP. Four molecules of ATP per glucose are actually produced, however, two are consumed as part of the preparatory phase. The initial phosphorylation of glucose is required to increase the reactivity (decrease its stability) in order for the molecule to be cleaved into two pyruvate molecules by the enzyme aldolase. During the pay-off phase of glycolysis, four phosphate groups are transferred to ADP by substrate-level phosphorylation to make four ATP, and two
Cellular respiration
1695248
ATP. For the glucose molecule to oxidize into pyruvate, an input of ATP molecules is required. This is known as the investment phase, in which a total of two ATP molecules are consumed. At the end of glycolysis, the total yield of ATP is four molecules, but the net gain is two ATP molecules. Even though ATP is synthesized, the two ATP molecules produced are few compared to the second and third pathways, Krebs cycle and oxidative phosphorylation. Even if there is no oxygen present, glycolysis can continue to generate ATP. However, for glycolysis to continue to produce ATP, there
Carbohydrate catabolism
85517
are: two GTP, six NADH, two QH, and four CO. The above reactions are balanced if P represents the HPO ion, ADP and GDP the ADP and GDP ions, respectively, and ATP and GTP the ATP and GTP ions, respectively. The total number of ATP molecules obtained after complete oxidation of one glucose in glycolysis, citric acid cycle, and oxidative phosphorylation is estimated to be between 30 and 38. The theoretical maximum yield of ATP through oxidation of one molecule of glucose in glycolysis, citric acid cycle, and oxidative phosphorylation is 38 (assuming 3 molar equivalents of ATP per equivalent
Citric acid cycle
6412239
phosphoglycerate kinase undergoes a substrate induced conformational change similar to another metabolic enzyme called hexokinase. Because two molecules of glyceraldehyde-3-phosphate are formed during glycolysis from one molecule of glucose, 1,3BPG can be said to responsible for two of the ten molecules of ATP produced during the entire process. Glycolysis also uses two molecules of ATP in its initial stages as a committed and irreversible step. For this reason glycolysis is not reversible and has a net produce of 2 molecules of ATP and two of NADH. The two molecules of NADH themselves go on to produce approximately 3 molecules of
1,3-Bisphosphoglyceric acid
1605777
Anaerobic glycolysis Anaerobic glycolysis is the transformation of glucose to lactate when limited amounts of oxygen (O) are available. Anaerobic glycolysis is only an effective means of energy production during short, intense exercise, providing energy for a period ranging from 10 seconds to 2 minutes. The anaerobic glycolysis (lactic acid) system is dominant from about 10–30 seconds during a maximal effort. It replenishes very quickly over this period and produces 2 ATP molecules per glucose molecule or about 5% of glucose's energy potential (38 ATP molecules). The speed at which ATP is produced is about 100 times that of oxidative
Anaerobic glycolysis
167845
for subsequent breakdown in later steps of glycolysis. At physiological conditions, this initial reaction is irreversible. In anaerobic respiration, one glucose molecule produces a net gain of two ATP molecules (four ATP molecules are produced during glycolysis through substrate-level phosphorylation, but two are required by enzymes used during the process). In aerobic respiration, a molecule of glucose is much more profitable in that a maximum net production of 30 or 32 ATP molecules (depending on the organism) through oxidative phosphorylation is generated. Tumor cells often grow comparatively quickly and consume an above-average amount of glucose by glycolysis, which leads to
Glucose
1695247
molecules of ATP is therefore one of the most important biochemical pathways found in living organisms. Glycolysis, which means “sugar splitting,” is the initial process in the cellular respiration pathway. Glycolysis can be either an aerobic or anaerobic process. When oxygen is present, glycolysis continues along the aerobic respiration pathway. If oxygen is not present, then ATP production is restricted to anaerobic respiration. The location where glycolysis, aerobic or anaerobic, occurs is in the cytosol of the cell. In glycolysis, a six-carbon glucose molecule is split into two three-carbon molecules called pyruvate. These carbon molecules are oxidized into NADH and
Carbohydrate catabolism
1695253
and the Krebs cycle. While the ATP count is glycolysis and the Krebs cycle is two ATP molecules, the electron transport chain contributes, at most, twenty-eight ATP molecules. A contributing factor is due to the energy potentials of NADH and FADH. As they are brought from the initial process, glycolysis, to the electron transport chain, the energy stored in them are now utilized. A second contributing factor is that cristae, the inner membranes of mitochondria, increase the surface area and therefore the amount of proteins in the membrane that assist in the synthesis of ATP. Along the electron transport chain,
Carbohydrate catabolism
5297954
substrate-level phosphorylation. The second substrate-level phosphorylation occurs by dephosphorylating phosphoenolpyruvate, catalyzed by pyruvate kinase, producing pyruvate and ATP. During the preparatory phase, each 6-carbon glucose molecule is broken into two 3-carbon molecules. Thus, in glycolysis dephosphorylation results in the production of 4 ATP. However, the prior preparatory phase consumes 2 ATP, so the net yield in glycolysis is 2 ATP. 2 molecules of NADH are also produced and can be used in oxidative phosphorylation to generate more ATP. ATP can be generated by substrate-level phosphorylation in mitochondria in a pathway that is independent from the proton motive force. In the
Substrate-level phosphorylation
4494243
supplied to the muscles through the bloodstream; it is ready to be fed into further glycolysis reactions. If muscle activity has stopped, the glucose is used to replenish the supplies of glycogen through glycogenesis. Overall, the glycolysis part of the cycle produces 2 ATP molecules at a cost of 6 ATP molecules consumed in the gluconeogenesis part. Each iteration of the cycle must be maintained by a net consumption of 4 ATP molecules. As a result, the cycle cannot be sustained indefinitely. The intensive consumption of ATP molecules indicates that the Cori cycle shifts the metabolic burden from the muscles
Cori cycle
162549
prosthetic group. Triosephosphate isomerase rapidly interconverts dihydroxyacetone phosphate with glyceraldehyde 3-phosphate (GADP) that proceeds further into glycolysis. This is advantageous, as it directs dihydroxyacetone phosphate down the same pathway as glyceraldehyde 3-phosphate, simplifying regulation. The second half of glycolysis is known as the pay-off phase, characterised by a net gain of the energy-rich molecules ATP and NADH. Since glucose leads to two triose sugars in the preparatory phase, each reaction in the pay-off phase occurs twice per glucose molecule. This yields 2 NADH molecules and 4 ATP molecules, leading to a net gain of 2 NADH molecules and 2 ATP
Glycolysis
7916753
energy in comparison to respiration. Mixed acid fermentation in "E. coli" occurs in two stages. These stages are outlined by the biological database for "E. coli", EcoCyc. The first of these two stages is a glycolysis reaction. Under anaerobic conditions, a glycolysis reaction takes place where glucose is converted into pyruvate: glucose → 2 pyruvate There is a net production of 2 ATP and 2 NADH molecules per molecule of glucose converted. ATP is generated by substrate-level phosphorylation. NADH is formed from the reduction of NAD. In the second stage, pyruvate produced by glycolysis is converted to one or more
Mixed acid fermentation
2356896
FADH, which drive the creation of ATP in other processes. A molecule of NADH can produce 1.5–2.5 molecules of ATP, whereas a molecule of FADH will yield 1.5 molecules of ATP. Typically, the complete breakdown of one molecule of glucose via aerobic respiration (i.e. involving both glycolysis and the Citric Acid Cycle) is usually about 30–32 molecules of ATP. Oxidation of one gram of carbohydrate yields approximately 4 kcal of energy. Glucoregulation is the maintenance of steady levels of glucose in the body. Hormones released from the pancreas regulate the overall metabolism of glucose. Insulin and glucagon are the primary
Carbohydrate metabolism
9006986
ATPs produced in glycolysis (3/NADH), ultimately resulting in a net gain of 38 ATP molecules per molecule of glucose metabolized. Compare this to the glycerol 3-phosphate shuttle, which reduces FAD to produce FADH, donates electrons to the quinone pool in the electron transport chain, and is capable of generating only 2 ATPs per NADH generated in glycolysis (ultimately resulting in a net gain of 36 ATPs per glucose metabolized). (These ATP numbers are prechemiosmotic, and should be reduced in light of the work of Mitchell and many others. Each NADH produced only 2.5 ATPs, and each FADH produces only 1.5
Malate-aspartate shuttle
162536
as part of glycolysis. These further aerobic reactions use pyruvate and NADH + H from glycolysis. Eukaryotic aerobic respiration produces approximately 34 additional molecules of ATP for each glucose molecule, however most of these are produced by a vastly different mechanism to the substrate-level phosphorylation in glycolysis. The lower-energy production, per glucose, of anaerobic respiration relative to aerobic respiration, results in greater flux through the pathway under hypoxic (low-oxygen) conditions, unless alternative sources of anaerobically oxidizable substrates, such as fatty acids, are found. The pathway of glycolysis as it is known today took almost 100 years to fully discover. The
Glycolysis
162535
four hydroxyl groups, giving ATPMg. When these differences along with the true charges on the two phosphate groups are considered together, the net charges of −4 on each side are balanced. For simple fermentations, the metabolism of one molecule of glucose to two molecules of pyruvate has a net yield of two molecules of ATP. Most cells will then carry out further reactions to 'repay' the used NAD and produce a final product of ethanol or lactic acid. Many bacteria use inorganic compounds as hydrogen acceptors to regenerate the NAD. Cells performing aerobic respiration synthesize much more ATP, but not
Glycolysis
3937221
Finally, pyruvate is converted to ethanol and CO in two steps, regenerating oxidized NAD+ needed for glycolysis: catalyzed by pyruvate decarboxylase This reaction is catalyzed by alcohol dehydrogenase (ADH1 in baker's yeast). As shown by the reaction equation, glycolysis causes the reduction of two molecules of NAD to NADH. Two ADP molecules are also converted to two ATP and two water molecules via substrate-level phosphorylation. Fermentation of sugar to ethanol and CO can also be done by "Zymomonas mobilis", however the path is slightly different since formation of pyruvate does not happen by glycolysis but instead by the Entner–Doudoroff pathway.
Ethanol fermentation
162551
phosphate as a substrate to form 1-arseno-3-phosphoglycerate. This, however, is unstable and readily hydrolyzes to form 3-phosphoglycerate, the intermediate in the next step of the pathway. As a consequence of bypassing this step, the molecule of ATP generated from 1-3 bisphosphoglycerate in the next reaction will not be made, even though the reaction proceeds. As a result, arsenate is an uncoupler of glycolysis. This step is the enzymatic transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP by phosphoglycerate kinase, forming ATP and 3-phosphoglycerate. At this step, glycolysis has reached the break-even point: 2 molecules of ATP were consumed, and
Glycolysis
2356890
consists of ten steps, split into two phases. During the first phase, it requires the breakdown of two ATP molecules. During the second phase, chemical energy from the intermediates is transferred into ATP and NADH. The breakdown of one molecule of glucose results in two molecules of pyruvate, which can be further oxidized to access more energy in later processes. Gluconeogenesis is the reverse process of glycolysis. It involves the conversion of non-carbohydrate molecules into glucose. The non-carbohydrate molecules that are converted in this pathway include pyruvate, lactate, glycerol, alanine, and glutamine. This process occurs when there are lowered amounts
Carbohydrate metabolism
42888
regenerates the glucose, using a process called gluconeogenesis. This process is not quite the opposite of glycolysis, and actually requires three times the amount of energy gained from glycolysis (six molecules of ATP are used, compared to the two gained in glycolysis). Analogous to the above reactions, the glucose produced can then undergo glycolysis in tissues that need energy, be stored as glycogen (or starch in plants), or be converted to other monosaccharides or joined into di- or oligosaccharides. The combined pathways of glycolysis during exercise, lactate's crossing via the bloodstream to the liver, subsequent gluconeogenesis and release of glucose
Biochemistry
162589
is ongoing research to affect mitochondrial metabolism and treat cancer by reducing glycolysis and thus starving cancerous cells in various new ways, including a ketogenic diet. Some of the metabolites in glycolysis have alternative names and nomenclature. In part, this is because some of them are common to other pathways, such as the Calvin cycle. Glycolysis Glycolysis (from "glycose", an older term for glucose + "-lysis" degradation) is the metabolic pathway that converts glucose CHO, into pyruvate, CHCOCOO + H. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced
Glycolysis
15444525
process of glycolysis; this step is when the fructose 1,6-bisphosphate molecule breaks down into two molecules of dihydroxyacetone phosphate (DHAP), so from this point on whenever ATP is being generated from ADP there are really two ATP molecules generated because there are two molecules undergoing the same reaction. One molecule that takes advantage of this second part of the metabolic process is the fatty molecule glycerol. This is unfortunately prevented if someone is experiencing Glycerol Kinase Deficiency. Glycerol Kinase Deficiency causes the condition known as hyperglycerolemia, an accumulation of glycerol in the blood and urine. This excess of glycerol in
Glycerol kinase deficiency
3511838
from the cytoplasm. This "costs" one "extra" proton import per ATP, hence the actual efficiency is only 65% (= 2.4/3.67). The complete breakdown of glucose in the presence of oxygen is called cellular respiration. The last steps of this process occur in mitochondria. The reduced molecules NADH and FADH are generated by the Krebs cycle, glycolysis, and pyruvate processing. These molecules pass electrons to an electron transport chain, which uses the energy released to create a proton gradient across the inner mitochondrial membrane. ATP synthase then uses the energy stored in this gradient to make ATP. This process is called
Chemiosmosis
304644
The amount of energy released by oxidative phosphorylation is high, compared with the amount produced by anaerobic fermentation. Glycolysis produces only 2 ATP molecules, but somewhere between 30 and 36 ATPs are produced by the oxidative phosphorylation of the 10 NADH and 2 succinate molecules made by converting one molecule of glucose to carbon dioxide and water, while each cycle of beta oxidation of a fatty acid yields about 14 ATPs. These ATP yields are theoretical maximum values; in practice, some protons leak across the membrane, lowering the yield of ATP. The electron transport chain carries both protons and electrons,
Oxidative phosphorylation
983016
to make ATP but generates heat. This is particularly important in brown fat thermogenesis of newborn and hibernating mammals. According to some of newer sources the ATP yield during aerobic respiration is not 36–38, but only about 30–32 ATP molecules / 1 molecule of glucose , because: So finally we have, per molecule of glucose Altogether this gives 4 + 3 (or 5) + 20 + 3 = 30 (or 32) ATP per molecule of glucose The total ATP yield in ethanol or lactic acid fermentation is only 2 molecules coming from glycolysis, because pyruvate is not transferred to the
Cellular respiration
2356889
only a few of the more complex carbohydrates. The disaccharide lactose, for instance, requires the enzyme lactase to be broken into its monosaccharide components, glucose and galactose. Glycolysis is the process of breaking down a glucose molecule into two pyruvate molecules, while storing energy released during this process as ATP and NADH. Nearly all organisms that break down glucose utilize glycolysis. Glucose regulation and product use are the primary categories in which these pathways differ between organisms. In some tissues and organisms, glycolysis is the sole method of energy production. This pathway is anaerobic, because it doesn’t require oxygen. Glycolysis
Carbohydrate metabolism
4442442
certain circumstances. Mitochondrial inheritance is therefore non-Mendelian, as Mendelian inheritance presumes that half the genetic material of a fertilized egg (zygote) derives from each parent. Eighty percent of mitochondrial DNA codes for mitochondrial RNA, and therefore most mitochondrial DNA mutations lead to functional problems, which may be manifested as muscle disorders (myopathies). Because they provide 30 molecules of ATP per glucose molecule in contrast to the 2 ATP molecules produced by glycolysis, mitochondria are essential to all higher organisms for sustaining life. The mitochondrial diseases are genetic disorders carried in mitochondrial DNA, or nuclear DNA coding for mitochondrial components. Slight
Human mitochondrial genetics
162532
Glycolysis Glycolysis (from "glycose", an older term for glucose + "-lysis" degradation) is the metabolic pathway that converts glucose CHO, into pyruvate, CHCOCOO + H. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). Glycolysis is a sequence of ten enzyme-catalyzed reactions. Most monosaccharides, such as fructose and galactose, can be converted to one of these intermediates. The intermediates may also be directly useful. For example, the intermediate dihydroxyacetone phosphate (DHAP) is a source of the glycerol that combines with fatty acids to form fat. Glycolysis
Glycolysis
1985140
as the light profile. The light undergoes optical modulation instability, spontaneous dividing into a multitude of optical filaments, and the polymer system thereby forms filaments within the blend structure. The result is a new system that couples optical autocatalytic behavior to spinodal decompositon. It is known that an important metabolic cycle, glycolysis, displays temporal order. Glycolysis consists of the degradation of one molecule of glucose and the overall production of two molecules of ATP. The process is therefore of great importance to the energetics of living cells. The global glycolysis reaction involves glucose, ADP, NAD, pyruvate, ATP, and NADH. The
Autocatalysis
983005
ADP and a phosphate group. Biology textbooks often state that 38 ATP molecules can be made per oxidised glucose molecule during cellular respiration (2 from glycolysis, 2 from the Krebs cycle, and about 34 from the electron transport system). However, this maximum yield is never quite reached because of losses due to leaky membranes as well as the cost of moving pyruvate and ADP into the mitochondrial matrix, and current estimates range around 29 to 30 ATP per glucose. Aerobic metabolism is up to 15 times more efficient than anaerobic metabolism (which yields 2 molecules ATP per 1 molecule glucose).
Cellular respiration
983014
coenzymes are oxidized by the electron transport chain and used for oxidative phosphorylation. Although there is a theoretical yield of 38 ATP molecules per glucose during cellular respiration, such conditions are generally not realized because of losses such as the cost of moving pyruvate (from glycolysis), phosphate, and ADP (substrates for ATP synthesis) into the mitochondria. All are actively transported using carriers that utilize the stored energy in the proton electrochemical gradient. The outcome of these transport processes using the proton electrochemical gradient is that more than 3 H are needed to make 1 ATP. Obviously this reduces the theoretical
Cellular respiration
10163757
lactic acid system is used predominately for the "kick" at the end of a race. This stage of the aerobic system occurs on the cristae (infoldings on the membrane of the mitochondria). The NADH+ from glycolysis and the Krebs cycle, and the FADH+ from the Krebs cycle produce electron carriers at decreasing energy levels, in which energy is released to reform ATP. Each NADH+ that travels this electron transport chain provides enough energy for 3 molecules of ATP, and each molecule of FADH+ provides enough energy for 2 molecules of ATP. If you do your math this means that 10
Bioenergetic systems
3937220
of sucrose (CHO) into ethanol (CHOH). Alcoholic fermentation converts one mole of glucose into two moles of ethanol and two moles of carbon dioxide, producing two moles of ATP in the process. The overall chemical formula for alcoholic fermentation is: Sucrose is a dimer of glucose and fructose molecules. In the first step of alcoholic fermentation, the enzyme invertase cleaves the glycosidic linkage between the glucose and fructose molecules. Next, each glucose molecule is broken down into two pyruvate molecules in a process known as glycolysis. Glycolysis is summarized by the equation: CHCOCOO is pyruvate, and P is inorganic phosphate.
Ethanol fermentation
262307
ATP from glucose has an approximately 13-times higher yield during aerobic respiration compared to fermentation. Plant mitochondria can also produce a limited amount of ATP without oxygen by using the alternate substrate nitrite. ATP crosses out through the inner membrane with the help of a specific protein, and across the outer membrane via porins. ADP returns via the same route. Pyruvate molecules produced by glycolysis are actively transported across the inner mitochondrial membrane, and into the matrix where they can either be oxidized and combined with coenzyme A to form CO, acetyl-CoA, and NADH, or they can be carboxylated (by
Mitochondrion
9950294
to the German chemist Emil Fischer who received the Nobel Prize in chemistry nearly 60 years earlier. Since metabolism focuses on the breaking down (catabolic processes) of molecules and the building of larger molecules from these particles (anabolic processes), the use of glucose and its involvement in the formation of adenosine triphosphate (ATP) is fundamental to this understanding. The most frequent type of glycolysis found in the body is the type that follows the Embden-Meyerhof-Parnas (EMP) Pathway, which was discovered by Gustav Embden, Otto Meyerhof, and Jakob Karol Parnas. These three men discovered that glycolysis is a strongly determinant process
History of biochemistry
17622
to two pyruvates . In Step 7, two ATP are produced. In addition, in Step 10, two further equivalents of ATP are produced. In Steps 7 and 10, ATP is generated from ADP. A net of two ATPs are formed in the glycolysis cycle. The glycolysis pathway is later associated with the Citric Acid Cycle which produces additional equivalents of ATP. In glycolysis, hexokinase is directly inhibited by its product, glucose-6-phosphate, and pyruvate kinase is inhibited by ATP itself. The main control point for the glycolytic pathway is phosphofructokinase (PFK), which is allosterically inhibited by high concentrations of ATP and
Adenosine triphosphate
897322
performed via aerobic respiration in the mitochondria. Plants use photosynthetic pathways to convert and store energy from sunlight, also conversion of ADP to ATP. Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance. The ten-step catabolic pathway of glycolysis is the initial phase of free-energy release in the breakdown of glucose and can be split into two phases, the preparatory phase and payoff phase. ADP and phosphate are needed as precursors to synthesize ATP in the payoff reactions of
Adenosine diphosphate
162574
(At lower exercise intensities it can sustain muscle activity in diving animals, such as seals, whales and other aquatic vertebrates, for very much longer periods of time.) Under these conditions NAD is replenished by NADH donating its electrons to pyruvate to form lactate. This produces 2 ATP molecules per glucose molecule, or about 5% of glucose's energy potential (38 ATP molecules in bacteria). But the speed at which ATP is produced in this manner is about 100 times that of oxidative phosphorylation. The pH in the cytoplasm quickly drops when hydrogen ions accumulate in the muscle, eventually inhibiting the enzymes
Glycolysis
983006
However some anaerobic organisms, such as methanogens are able to continue with anaerobic respiration, yielding more ATP by using other inorganic molecules (not oxygen) as final electron acceptors in the electron transport chain. They share the initial pathway of glycolysis but aerobic metabolism continues with the Krebs cycle and oxidative phosphorylation. The post-glycolytic reactions take place in the mitochondria in eukaryotic cells, and in the cytoplasm in prokaryotic cells. 1. Glycolysis: --- "2 ATPs + Glucose → 2 Pyruvic Acid + 4 Hydrogen + 4 ATPs" 2. Formation of Acetyl CoA: --- "2 Pyruvic Acid + 2 CoA → 2
Cellular respiration
281062
reaction is the phosphorylation of fructose-6-phosphate to form the intermediate fructose-1,6-bisphosphate by the enzyme phosphofructokinase accompanied by the hydrolysis of ATP in the pathway of glycolysis. The resulting chemical reaction within the metabolic pathway is highly thermodynamically favorable and, as a result, irreversible in the cell. formula_1 A core set of energy-producing catabolic pathways occur within all living organisms in some form. These pathways transfer the energy released by breakdown of nutrients into ATP and other small molecules used for energy (e.g. GTP, NADPH, FADH). All cells can perform anaerobic respiration by glycolysis. Additionally, most organisms can perform more efficient
Metabolic pathway
4338047
by the mitochondrial membrane potential. The membrane only allows nonpolar molecules such as CO and O and small non charged polar molecules such as HO to enter the matrix. Molecules enter and exit the mitochondrial matrix through transport proteins and ion transporters. Molecules are then able to leave the mitochondria through porin. These attributed characteristics allow for control over concentrations of ions and metabolites necessary for regulation and determines the rate of ATP production. Following glycolysis, the citric acid cycle is activated by the production of acetyl-CoA. The oxidation of pyruvate by Pyruvate dehydrogenase in the matrix produces CO, acetyl-CoA,
Mitochondrial matrix
860620
enzymes are dehydrogenases, although reductases are also common. The accepted nomenclature for dehydrogenases is "donor dehydrogenase," where the donor is the substrate that can be oxidized. Oxidation-reduction reactions are essential to growth and survival of organisms, as the oxidation of organic molecules produces energy. Energy-producing reactions can drive forward the synthesis of important energy molecules, such as ATP in glycolysis. For this reason, dehydrogenases have pivotal roles in metabolism. Dehydrogenases oxidize a substrate by transferring hydrogen to an electron acceptor, common electron acceptors being NAD or FAD. This would be considered an oxidation of the substrate, in which the substrate
Dehydrogenase
616959
Kinase In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the substrate gains a phosphate group and the high-energy ATP molecule donates a phosphate group. This transesterification produces a phosphorylated substrate and ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and ADP gains a phosphate group (producing a dephosphorylated substrate and the high energy molecule of ATP). These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis. Kinases are part of the
Kinase
2754123
is by phosphorylating the enzyme at the serine residues. The HSV-1 induced glycolysis increases ATP content, which is critical for the virus’s replication. Phosphofructokinase 1 Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes () of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it
Phosphofructokinase 1
85534
fatty acids are broken down through a process known as beta oxidation, which results in the production of mitochondrial "acetyl-CoA", which can be used in the citric acid cycle. Beta oxidation of fatty acids with an odd number of methylene bridges produces propionyl-CoA, which is then converted into "succinyl-CoA" and fed into the citric acid cycle as an anaplerotic intermediate. The total energy gained from the complete breakdown of one (six-carbon) molecule of glucose by glycolysis, the formation of 2 "acetyl-CoA" molecules, their catabolism in the citric acid cycle, and oxidative phosphorylation equals about 30 ATP molecules, in eukaryotes. The
Citric acid cycle
12561008
form of creatine phosphate which is generated from ATP and can regenerate ATP when needed with creatine kinase. Muscles also keep a storage form of glucose in the form of glycogen. Glycogen can be rapidly converted to glucose when energy is required for sustained, powerful contractions. Within the voluntary skeletal muscles, the glucose molecule can be metabolized anaerobically in a process called glycolysis which produces two ATP and two lactic acid molecules in the process (note that in aerobic conditions, lactate is not formed; instead pyruvate is formed and transmitted through the citric acid cycle). Muscle cells also contain globules
Muscle
1695225
is able to hydrolyze the peptide bonds by using ATP energy. This process is further helped by the use of enzymes called proteases. The proteases help cleave off the remaining peptide residues to produce individual amino acids, ready to be converted into usable molecules for either glycolysis or the TCA cycle, to produce energy for the organisms, or to be used to create new proteins. Different types of proteases help cleave the proteins in different formats. There are serine, aspartate, metalloproteases, and many other classes. All use different mechanisms to cleave the peptide bonds to begin protein degradation. For example,
Protein catabolism
983009
NADH are produced when the pyruvate are oxidized. The overall reaction can be expressed this way: Starting with glucose, 1 ATP is used to donate a phosphate to glucose to produce glucose 6-phosphate. Glycogen can be converted into glucose 6-phosphate as well with the help of glycogen phosphorylase. During energy metabolism, glucose 6-phosphate becomes fructose 6-phosphate. An additional ATP is used to phosphorylate fructose 6-phosphate into fructose 1,6-disphosphate by the help of phosphofructokinase. Fructose 1,6-diphosphate then splits into two phosphorylated molecules with three carbon chains which later degrades into pyruvate. Glycolysis can be literally translated as "sugar splitting". Pyruvate is
Cellular respiration
17620
pathways in eukaryotes are (1) glycolysis, (2) the citric acid cycle/oxidative phosphorylation, and (3) beta-oxidation. The overall process of oxidizing glucose to carbon dioxide, the combination of pathways 1 and 2, is known as cellular respiration, produces about 30 equivalents of ATP from each molecule of glucose. ATP production by a non-photosynthetic aerobic eukaryote occurs mainly in the mitochondria, which comprise nearly 25% of the volume of a typical cell. In glycolysis, glucose and glycerol are metabolized to pyruvate. Glycolysis generates two equivalents of ATP through substrate phosphorylation catalyzed by two enzymes, PGK and pyruvate kinase. Two equivalents of NADH
Adenosine triphosphate
17621
are also produced, which can be oxidized via the electron transport chain and result in the generation of additional ATP by ATP synthase. The pyruvate generated as an end-product of glycolysis is a substrate for the Krebs Cycle. Glycolysis is viewed as consisting of two phases with five steps each. Phase 1, "the preparatory phase", glucose is converted to 2 d-glyceraldehyde -3-phosphate (g3p). One ATP is invested in the Step 1, and another ATP is invested in Step 3. Steps 1 and 3 of glycolysis are referred to as "Priming Steps". In Phase 2, two equivalents of g3p are converted
Adenosine triphosphate
2754108
Phosphofructokinase 1 Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes () of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it is one of the key regulatory and rate limiting steps of glycolysis. PFK is able to regulate glycolysis through allosteric inhibition, and in
Phosphofructokinase 1
262312
of FADH) that are a source of electrons for the "electron transport chain", and a molecule of GTP (that is readily converted to an ATP). The redox energy from NADH and FADH is transferred to oxygen (O) in several steps via the electron transport chain. These energy-rich molecules are produced within the matrix via the citric acid cycle but are also produced in the cytoplasm by glycolysis. Reducing equivalents from the cytoplasm can be imported via the malate-aspartate shuttle system of antiporter proteins or feed into the electron transport chain using a glycerol phosphate shuttle. Protein complexes in the inner
Mitochondrion
8581833
insoluble chunks of cellulose into smaller, soluble cellodextrins which can be used by the cell. Many cellulolytic bacteria use cellodextrins as their primary source of energy. The energy is obtained through the phosphorolytic cleavage of glycosidic bonds as well as the anaerobic glycolysis of the glucose monomers. Transport of cellodextrins across the cell membrane is usually an active process, requiring ATP. Cellodextrin Cellodextrins are glucose polymers of varying length (two or more glucose monomers) resulting from cellulolysis, the breakdown of cellulose. A cellodextrin is classified by its degree of polymerization (DP) which indicates the number of linked glucose monomers it
Cellodextrin
162587
often results in hypoxia (decreased O2 supply) within the tumor cells. Thus, these cells rely on anaerobic metabolic processes such as glycolysis for ATP (adenosine triphosphate). Some tumor cells overexpress specific glycolytic enzymes which result in higher rates of glycolysis. Often these enzymes are Isoenzymes, of traditional glycolysis enzymes, that vary in their susceptibility to traditional feedback inhibition. The increase in glycolytic activity ultimately counteracts the effects of hypoxia by generating sufficient ATP from this anaerobic pathway. This phenomenon was first described in 1930 by Otto Warburg and is referred to as the Warburg effect. The Warburg hypothesis claims that
Glycolysis
2356895
glycolysis pathway and is later cleaved into glyceraldehyde and dihydroxyacetone phosphate. Lactose, or milk sugar, consists of one molecule of glucose and one molecule of galactose. After separation from glucose, galactose travels to the liver for conversion to glucose. Galactokinase uses one molecule of ATP to phosphorylate galactose. The phosphorylated galactose is then converted to glucose-1-phosphate, and then eventually glucose-6-phosphate, which can be broken down in glycolysis. Many steps of carbohydrate metabolism allow the cells to access energy, and store it more transiently in ATP. The cofactors NAD and FAD are sometimes reduced during this process to form NADH and
Carbohydrate metabolism
669847
glucose concentration outside the cell is high, glucose molecules move into the cell by facilitated diffusion, down its concentration gradient through the GLUT2 transporter. Since beta cells use glucokinase to catalyze the first step of glycolysis, metabolism only occurs around physiological blood glucose levels and above. Metabolism of the glucose produces ATP, which increases the ATP to ADP ratio. The ATP-sensitive potassium ion channels close when this ratio rises. This means that potassium ions can no longer diffuse out of the cell. As a result, the potential difference across the membrane becomes more positive (as potassium ions accumulate inside the
Beta cell
8341788
to ATP and convert NAD+ to NADH. The pyruvates break down into two acetaldehyde molecules and give off two carbon dioxide molecules as a waste product. The acetaldehyde is reduced into ethanol using the energy and hydrogen from NADH, and the NADH is oxidized into NAD+ so that the cycle may repeat. The reaction is catalysed by the enzymes pyruvate decarboxylase and alcohol dehydrogenase. "Homolactic fermentation" (producing only lactic acid) is the simplest type of fermentation. The pyruvate from glycolysis undergoes a simple redox reaction, forming lactic acid. It is unique because it is one of the only respiration processes
Fermentation
162552
2 new molecules have now been synthesized. This step, one of the two substrate-level phosphorylation steps, requires ADP; thus, when the cell has plenty of ATP (and little ADP), this reaction does not occur. Because ATP decays relatively quickly when it is not metabolized, this is an important regulatory point in the glycolytic pathway. ADP actually exists as ADPMg, and ATP as ATPMg, balancing the charges at -5 both sides. "Cofactors:" Mg Phosphoglycerate mutase isomerises 3-phosphoglycerate into 2-phosphoglycerate. Enolase next converts 2-phosphoglycerate to phosphoenolpyruvate. This reaction is an elimination reaction involving an E1cB mechanism. "Cofactors:" 2 Mg: one "conformational" ion
Glycolysis
19339779
cells have higher energy demands due to the continued proliferation and respiration produces significantly more ATP than glycolysis alone (fermentation produces no additional ATP). Typically, there is an up-regulation in glucose transporters and enzymes in the glycolysis pathway (also seen in yeast). There are many parallel aspects of aerobic fermentation in tumor cells that are also seen in Crabtree-positive yeasts. Further research into the evolution of aerobic fermentation in yeast such as "S. cerevisiae" can be a useful model for understanding aerobic fermentation in tumor cells. This has a potential for better understanding cancer and cancer treatments. Aerobic fermentation Aerobic
Aerobic fermentation
9663080
in the glycolysis pathway. The Pasteur effect will only occur if glucose concentrations are low (<2 g/L) and if other nutrients, mostly nitrogen, are limited. From the standpoint of ATP production then, it is advantageous for yeast to utilize the citric acid cycle in the presence of oxygen, as more ATP is produced from less glucose; however, Boulton et al. (1996) have maintained that yeast will follow the anaerobic, rather than aerobic, fermentative pathway if glucose is not limited, in that respiration, although capable of producing more ATP than glycolysis per molecule of glucose, also requires more energy in terms
Pasteur effect
897323
the TCA cycle and oxidative phosphorylation mechanism. During the payoff phase of glycolysis, the enzymes phosphoglycerate kinase and pyruvate kinase facilitate the addition of a phosphate group to ADP by way of substrate-level phosphorylation. Glycolysis is performed by all living organisms and consists of 10 steps. The net reaction for the overall process of glycolysis is: Steps 1 and 3 require the input of energy derived from the hydrolysis of ATP to ADP and P (inorganic phosphate), whereas steps 7 and 10 require the input of ADP, each yielding ATP. The enzymes necessary to break down glucose are found in
Adenosine diphosphate
162570
carbons into the pentose phosphate pathway. Pyruvate kinase enzyme catalyzes the last step of glycolysis, in which pyruvate and ATP are formed. Pyruvate kinase catalyzes the transfer of a phosphate group from phosphoenolpyruvate (PEP) to ADP, yielding one molecule of pyruvate and one molecule of ATP. Liver pyruvate kinase is indirectly regulated by epinephrine and glucagon, through protein kinase A. This protein kinase phosphorylates liver pyruvate kinase to deactivate it. Muscle pyruvate kinase is not inhibited by epinephrine activation of protein kinase A. Glucagon signals fasting (no glucose available). Thus, glycolysis is inhibited in the liver but unaffected in muscle
Glycolysis
18693254
cell type living organism. Magnesium in anaerobic prokaryotes can be found in MgATP. Magnesium also has many functions in prokaryotes such as glycolysis, all kinases, NTP reaction, signalling, DNA/RNA structures and light capture. In aerobic eukaryotes, magnesium can be found in cytoplasm and chloroplasts. The reactions in these cell compartments are glycolysis, photophosphorylation and carbon assimilation. ATP, the main source of energy in almost all living organisms, must bind with metal ions such as Mg or Ca to function. Examination of cells with limited magnesium supply has shown that a lack of magnesium can cause a decrease in ATP. Magnesium
Evolution of metal ions in biological systems
2296567
only in the seeds. These two molecules are converted in the body to methylene cyclopropyl acetic acid (MCPA). Hypoglycin A and MCPA are both toxic. MCPA and hypoglycin A inhibit several enzymes involved in the breakdown of acyl CoA compounds, often binding irreversibly to coenzyme A, carnitine and carnitine acyltransferases I and II, reducing their bioavailability and consequently inhibiting beta oxidation of fatty acids. Beta oxidation normally provides the body with ATP, NADH, and acetyl CoA which is used to supplement the energy produced by glycolysis. Glucose stores are consequently depleted leading to hypoglycemia. Clinically, this condition is called Jamaican
Ackee
7983256
and pyruvate. A key step for the regulation of glycolysis is an early reaction in the pathway catalysed by phosphofructokinase-1 (PFK1). When ATP levels rise, ATP binds an allosteric site in PFK1 to decrease the rate of the enzyme reaction; glycolysis is inhibited and ATP production falls. This negative feedback control helps maintain a steady concentration of ATP in the cell. However, metabolic pathways are not just regulated through inhibition since enzyme activation is equally important. With respect to PFK1, fructose 2,6-bisphosphate and ADP are examples of metabolites that are allosteric activators. Physiological enzyme inhibition can also be produced by
Enzyme inhibitor
2814516
to bind to a second substrate. Regulatory site ligands can involve homotropic and heterotropic ligands, in which single or multiple types of molecule affects enzyme activity respectively. Enzymes that are highly regulated are often essential in metabolic pathways. For example, phosphofructokinase (PFK), which phosphorylates fructose in glycolysis, is largely regulated by ATP. Its regulation in glycolysis is imperative because it is the committing and rate limiting step of the pathway. PFK also controls the amount of glucose designated to form ATP through the catabolic pathway. Therefore, at sufficient levels of ATP, PFK is allosterically inhibited by ATP. This regulation efficiently
Binding site
1844324
enzyme-catalyzed reactions. The pathway will begin in either the liver or kidney, in the mitochondria or cytoplasm of those cells, this being dependent on the substrate being used. Many of the reactions are the reverse of steps found in glycolysis. While most steps in gluconeogenesis are the reverse of those found in glycolysis, three regulated and strongly endergonic reactions are replaced with more kinetically favorable reactions. Hexokinase/glucokinase, phosphofructokinase, and pyruvate kinase enzymes of glycolysis are replaced with glucose-6-phosphatase, fructose-1,6-bisphosphatase, and PEP carboxykinase/pyruvate carboxylase. These enzymes are typically regulated by similar molecules, but with opposite results. For example, acetyl CoA and
Gluconeogenesis
983003
stronger bonds to form, thereby transferring energy for use by the cell) can then be used to drive processes requiring energy, including biosynthesis, locomotion or transportation of molecules across cell membranes. "Aerobic respiration" requires oxygen (O) in order to create ATP. Although carbohydrates, fats, and proteins are consumed as reactants, it is the preferred method of pyruvate breakdown in glycolysis and requires that pyruvate enter the mitochondria in order to be fully oxidized by the Krebs cycle. The products of this process are carbon dioxide and water, but the energy transferred is used to break bonds in ADP as the
Cellular respiration
4402421
major triumphs of bioenergetics is Peter D. Mitchell's chemiosmotic theory of how protons in aqueous solution function in the production of ATP in cell organelles such as mitochondria. This work earned Mitchell the 1978 Nobel Prize for Chemistry. Other cellular sources of ATP such as glycolysis were understood first, but such processes for direct coupling of enzyme activity to ATP production are not the major source of useful chemical energy in most cells. Chemiosmotic coupling is the major energy producing process in most cells, being utilized in chloroplasts and several single celled organisms in addition to mitochondria. Energy homeostasis is
Bioenergetics
17174832
unknown. TIGAR can promote development or inhibition of several cancers depending on the cellular context. TIGAR can have some effect on three characteristics of cancer; the ability to evade apoptosis, uncontrolled cell division, and altered metabolism. Many cancer cells have altered metabolism where the rate of glycolysis and anaerobic respiration are very high whilst oxidative respiration is low, which is called the Warburg Effect (or aerobic glycolysis). This allows cancer cells to survive under low oxygen conditions, and use molecules from respiratory pathways to synthesise amino acids and nucleic acids to maintain rapid growth. In Glioma, a type of brain
TP53-inducible glycolysis and apoptosis regulator
11293465
cell's energy needs are low, the reaction catalyzed by 1-phosphofructokinase is inhibited. When the cell is actively consuming ATP and stores deplete, the concentration of ATP lowers while the concentrations of AMP and ADP increase. AMP and ADP are both positive effectors of 1-phosphofructokinase and bind allosterically to activate the reaction. This activation encourages glycolysis and ATP production. Inhibition can also occur via citrate, a product of glycolysis and intermediate in the citric acid cycle. An increased concentration of citrate indicates the cell is meeting current energy needs, and therefore encourages allosteric inhibition of 1-phosphofructokinase allosterically via ATP. Allosteric regulation
1-phosphofructokinase
999849
which negative allosteric modulation can be seen is between ATP and the enzyme phosphofructokinase within the negative feedback loop that regulates glycolysis. Phosphofructokinase (generally referred to as PFK) is an enzyme that catalyses the third step of glycolysis: the phosphorylation of fructose-6-phosphate into fructose 1,6-bisphosphate. PFK can be allosterically inhibited by high levels of ATP within the cell. When ATP levels are high, ATP will bind to an allosteoric site on phosphofructokinase, causing a change in the enzyme's three-dimensional shape. This change causes its affinity for substrate (fructose-6-phosphate and ATP) at the active site to decrease, and the enzyme is
Allosteric regulation
162556
concentrations of each step, and the standard free energy changes, the actual free energy change can be calculated. (Neglecting this is very common - the delta G of ATP hydrolysis in cells is not the standard free energy change of ATP hydrolysis quoted in textbooks). From measuring the physiological concentrations of metabolites in an erythrocyte it seems that about seven of the steps in glycolysis are in equilibrium for that cell type. Three of the steps — the ones with large negative free energy changes — are not in equilibrium and are referred to as "irreversible"; such steps are often
Glycolysis
7915086
glycolysis). As oxygen is not required, fermentative organisms are anaerobic. Many organisms can use fermentation under anaerobic conditions and aerobic respiration when oxygen is present. These organisms are facultative anaerobes. To avoid the overproduction of NADH, obligately fermentative organisms usually do not have a complete citric acid cycle. Instead of using an ATP synthase as in respiration, ATP in fermentative organisms is produced by substrate-level phosphorylation where a phosphate group is transferred from a high-energy organic compound to ADP to form ATP. As a result of the need to produce high energy phosphate-containing organic compounds (generally in the form of
Microbial metabolism
12561009
of fat, which are used for energy during aerobic exercise. The aerobic energy systems take longer to produce the ATP and reach peak efficiency, and requires many more biochemical steps, but produces significantly more ATP than anaerobic glycolysis. Cardiac muscle on the other hand, can readily consume any of the three macronutrients (protein, glucose and fat) aerobically without a 'warm up' period and always extracts the maximum ATP yield from any molecule involved. The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise. At rest, skeletal muscle consumes 54.4 kJ/kg
Muscle
162534
will be limited to the Embden–Meyerhof–Parnas pathway. The glycolysis pathway can be separated into two phases: The overall reaction of glycolysis is: The use of symbols in this equation makes it appear unbalanced with respect to oxygen atoms, hydrogen atoms, and charges. Atom balance is maintained by the two phosphate (P) groups: Charges are balanced by the difference between ADP and ATP. In the cellular environment, all three hydroxyl groups of ADP dissociate into −O and H, giving ADP, and this ion tends to exist in an ionic bond with Mg, giving ADPMg. ATP behaves identically except that it has
Glycolysis
7915083
most basic metabolic models with eukaryotes, e. g. using glycolysis (also called EMP pathway) for sugar metabolism and the citric acid cycle to degrade acetate, producing energy in the form of ATP and reducing power in the form of NADH or quinols. These basic pathways are well conserved because they are also involved in biosynthesis of many conserved building blocks needed for cell growth (sometimes in reverse direction). However, many bacteria and archaea utilize alternative metabolic pathways other than glycolysis and the citric acid cycle. A well-studied example is sugar metabolism via the keto-deoxy-phosphogluconate pathway (also called ED pathway) in
Microbial metabolism
10153359
The glucose-1,6-bisphosphate increase the activity of glycolysis, of which glucose-6-phosphate is a reagent. In addition, one of the reactants (1,3-bisphosphoglycerate) and one of the products (3-phosphoglycerate) are intermediates in the 'payoff' phase of glycolysis. In other words, two molecules involved with glucose-1,6-bisphosphate synthase are able to be both created and recycled in the glycolytic pathway. The reactant glucose 1-phosphate is an important precursor molecule in many different pathways, including glycolysis, gluconeogenesis and the pentose phosphate pathway. Glucose-1,6-bisphosphate synthase is allosterically inhibited by inorganic phosphate, fructose-1,6-bisphosphate, 3-phosphoglycerate (a product), citrate, lithium, phosphoenolpyruvate (PEP), and acetyl CoA. The inhibition of the enzyme
Glucose-1,6-bisphosphate synthase
1695251
it back to pyruvate. If oxygen is present, then following glycolysis, the two pyruvate molecules are brought into the mitochondrion itself to go through the Krebs cycle. In this cycle, the pyruvate molecules from glycolysis are further broken down to harness the remaining energy. Each pyruvate goes through a series of reactions that converts it to acetyl coenzyme A. From here, only the acetyl group participates in the Krebs cycle—in which it goes through a series of redox reactions, catalyzed by enzymes, to further harness the energy from the acetyl group. The energy from the acetyl group, in the form
Carbohydrate catabolism
42887
the 2 quinols), totaling to 32 molecules of ATP conserved per degraded glucose (two from glycolysis + two from the citrate cycle). It is clear that using oxygen to completely oxidize glucose provides an organism with far more energy than any oxygen-independent metabolic feature, and this is thought to be the reason why complex life appeared only after Earth's atmosphere accumulated large amounts of oxygen. In vertebrates, vigorously contracting skeletal muscles (during weightlifting or sprinting, for example) do not receive enough oxygen to meet the energy demand, and so they shift to anaerobic metabolism, converting glucose to lactate. The liver
Biochemistry
16117770
and oscar contain the largest glycogen content (300-2000 µmol glocosyl units/g) in their tissue compared to hypoxia-sensitive fish, such as rainbow trout, which contain only 100 µmol glocosyl units/g. The more glycogen stored in a tissue indicates the capacity for that tissue to undergo glycolysis and produce ATP. When anaerobic pathways are turned on, glycogen stores are depleted and accumulation of acidic waste products occurs. This is known as a Pasteur effect. A challenge hypoxia-tolerant fish face is how to produce ATP anaerobically without creating a significant Pasteur effect. Along with a reduction in metabolism, some fish have adapted traits
Hypoxia in fish
20406126
C-sulfonate: 2,3-dihydroxypropanesulfonate (DHPS) or sulfolactate (SL). Two sulfoglycolytic processes are known. The sulfoglycolytic Embden-Meyerhof-Parnas (sulfo-EMP) pathway, first identified in "Escherichia coli", involves the degradation of sulfoquinovose to 2,3-dihydroxypropanesulfonate (DHPS), and shares similarity with the Embden-Meyerhof-Parnas glycolysis pathway. The sulfoglycolytic Entner-Doudoroff (sulfo-ED) pathway, first identified in "Pseudomonas putida" SQ1, involves the degradation of sulfoquinovose to sulfolactate, and shares similarity to the Entner-Doudoroff pathway of glycolysis. Both pathways lead to the production of dihydroxyacetone phosphate in processes that consume ATP. Energy is formed in later stages through the 'pay-off' phase of glycolysis through substrate-level phosphorylation to produce ATP and NADH. A range
Sulfoglycolysis
10163755
kinds of physical activities that humans are capable of performing. This system is known as anaerobic glycolysis. "Glycolysis" refers to the breakdown of sugar. In this system, the breakdown of sugar supplies the necessary energy from which ATP is manufactured. When sugar is metabolized anaerobically, it is only partially broken down and one of the byproducts is lactic acid. This process creates enough energy to couple with the energy requirements to resynthesize ATP. When H+ ions accumulate in the muscles causing the blood pH level to reach very low levels, temporary muscle fatigue results. Another limitation of the lactic acid
Bioenergetic systems
860628
mostly used in catabolic pathways, such as glycolysis, that break down energy molecules to produce ATP. The ratio of NAD to NADH is kept very high in the cell, keeping it readily available to act as an oxidizing agent. NADP differs from NAD only in the addition of a phosphate group to the adenosine 5-membered carbon ring. The addition of the phosphate does not alter the electron transport abilities of the carrier. The phosphate group creates enough contrast between the two groups that they bind to the active site of different enzymes, generally catalyzing different types of reactions. These two
Dehydrogenase
5297953
have no mitochondria, and in oxygen-depleted muscle. Substrate-level phosphorylation occurs in the cytoplasm of cells during glycolysis and in mitochondria either during the Krebs cycle or by MTHFD1L (EC 6.3.4.3), an enzyme interconverting ADP + phosphate + 10-formyltetrahydrofolate to ATP + formate + tetrahydrofolate (reversibly), under both aerobic and anaerobic conditions. In the pay-off phase of glycolysis, a net of 2 ATP are produced by substrate-level phosphorylation. The first substrate-level phosphorylation occurs after the conversion of 3-phosphoglyceraldehyde and Pi and NAD+ to 1,3-bisphosphoglycerate via glyceraldehyde 3-phosphate dehydrogenase. 1,3-bisphosphoglycerate is then dephosphorylated via phosphoglycerate kinase, producing 3-phosphoglycerate and ATP through a
Substrate-level phosphorylation
4469113
CO as its carbon source. Examples include plants. In contrast to photoautotrophs, photoheterotrophs are organisms that depend solely on light for their energy and principally on organic compounds for their carbon. Photoheterotrophs produce ATP through photophosphorylation but use environmentally obtained organic compounds to build structures and other bio-molecules. Phototroph Phototrophs ("Gr": φῶς, φωτός = light, τροϕή = nourishment) are the organisms that carry out photon capture to acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconception that phototrophs are obligatorily photosynthetic. Many, but not all, phototrophs often photosynthesize: they
Phototroph
85518
NADH and 2 ATP per FADH). In eukaryotes, two equivalents of NADH and four equivalents of ATP are generated in glycolysis, which takes place in the cytoplasm. Transport of two of these equivalents of NADH into the mitochondria consumes two equivalents of ATP, thus reducing the net production of ATP to 36. Furthermore, inefficiencies in oxidative phosphorylation due to leakage of protons across the mitochondrial membrane and slippage of the ATP synthase/proton pump commonly reduces the ATP yield from NADH and FADH to less than the theoretical maximum yield. The observed yields are, therefore, closer to ~2.5 ATP per NADH
Citric acid cycle
7549219
into the tricarboxylic acid (citric acid cycle or TCA cycle). This reduction in pyruvate flux into the TCA cycle decreases the rate of oxidative phosphorylation and oxygen consumption, reinforcing the glycolytic phenotype and sparing oxygen under hypoxic conditions. Pyruvate kinase type M2 or PKM2 is present in embryonic, adult stem cells. It is also expressed by many tumor cells. The alterations to metabolism by PKM2 increases ATP resources, stimulates macromolecular biosynthesis and redox control. Pyruvate kinase catalyses the ATP-generating step of glycolysis in which phosphoenolpyruvate (PEP) is converted to pyruvate. This is a rate-limiting step. It decreases the glycolysis activity
Tumor metabolome
17569558
table. Unlike phosphates, arsenates are not readily lost from minerals due to weathering. They are the predominant form of inorganic arsenic in aqueous aerobic environments. On the other hand, arsenite is more common in anaerobic environments, more mobile, and more toxic than arsenate. Arsenite is 25–60 times more toxic and more mobile than arsenate under most environmental conditions. Arsenate can lead to poisoning, since it can replace inorganic phosphate in the glyceraldehyde-3-phosphate --> 1,3-biphosphoglycerate step of glycolysis, producing 1-arseno-3-phosphoglycerate instead. Although glycolysis continues, 1 ATP molecule is lost. Thus, arsenate is toxic due to its ability to uncouple glycolysis. Arsenate
Arsenate-reducing bacteria
17488261
to utilize peptides for growth. "M. burtonii" has the capacity for glycolysis and gluconeogenesis. It produces acetyl-CoA from methyl-tetrahydrosarcinapterin and carbon dioxide. The enzyme used in this pathway is carbon monoxide dehydrogenase/acetyl-CoA synthase. "M. burtonii" possesses a type-III ribulose,1-5-bisphosphate carboxylase/oxygenase, however no identifiable gene for phosphoribulokinase has been found. Therefore, "M. burtonii" cannot accomplish carbon fixation by RubisCO. Also, "M. burtonii" has ADP-dependent sugar kinases used in glycolysis. When energy levels are low and/or the environment is anaerobic, "M. burtonii" utilizes ATP via this pathway given the ability of ATP synthesis through 3-PGA. "M. burtonii" produces cysteine via the tRNA-dependent
Methanococcoides burtonii
5640548
from a mineral during weathering. Examples of arsenate-containing minerals include adamite, alarsite, annabergite, erythrite and legrandite. Where two arsenate ions are required to balance the charge in a formula, it is called diarsenate for example trizinc diarsenate, Zn(AsO). Arsenate can replace inorganic phosphate in the step of glycolysis that produces 1,3-bisphosphoglycerate from glyceraldehyde 3-phosphate. This yields 1-arseno-3-phosphoglycerate instead, which is unstable and quickly hydrolyzes, forming the next intermediate in the pathway, 3-phosphoglycerate. Therefore, glycolysis proceeds, but the ATP molecule that would be generated from 1,3-bisphosphoglycerate is lost – arsenate is an uncoupler of glycolysis, explaining its toxicity. As with other
Arsenate
11903488
from them. During glycolysis ATP, NADH (both an energy transport form used inside cells) as well as pyruvate are produced. Glycolysis is taking place in the cytosol, and the created pyruvate needs to be transported to the mitochondrion, where further energy can extracted through the conversion of pyruvate to lactate, and through the citric acid cycle (CAC) (see below, c.f. bioenergetic systems). The liver can also create glucose (gluconeogenesis, see below); during times of low carbohydrate supply from the digestive system, the liver creates glucose and supplies it to other organs. Most enzymes of glycolysis also participate in gluconeogenesis, as
Inborn errors of carbohydrate metabolism
616979
reactions catalyzed by kinases. The anhydride linkage in 1,3 bisphosphoglycerate is unstable and has a high energy. 1,3-bisphosphogylcerate kinase requires ADP to carry out its reaction yielding 3-phosphoglycerate and ATP. In the final step of glycolysis, pyruvate kinase transfers a phosphoryl group from phosphoenolpyruvate to ADP, generating ATP and pyruvate. Hexokinase is the most common enzyme that makes use of glucose when it first enters the cell. It converts D-glucose to glucose-6-phosphate by transferring the gamma phosphate of an ATP to the C6 position. This is an important step in glycolysis because it traps glucose inside the cell due to
Kinase
1626665
molecules of water (HO). By accepting the electrons, oxygen allows the electron transport chain to continue functioning. The electrons from each NADH molecule can form a total of 3 ATP's from ADPs and phosphate groups through the electron transport chain, while each FADH molecule can produce a total of 2 ATPs. As a result, 10 NADH molecules (from glycolysis and the Krebs cycle), along with 2 FADH molecules, can form a total of 34 ATPs during aerobic respiration (from a single electron transport chain). This means that combined with the Krebs Cycle and glycolysis, the efficiency for the electron transport
Crista
9404259
lipid synthesis. The main function that the glycosome serves is of the glycolytic pathway that is done inside its membrane. By compartmentalizing glycolysis inside of the glycosome, the cell can be more successful. In the cell, action in the cytosol, the mitochondria, and the glycosome are all completing the function of energy metabolism. This energy metabolism generates ATP through the process of glycolysis. The glycosome is a host of the main glycolytic enzymes in the pathway for glycolysis. This pathway is used to break down fatty acids for their carbon and energy. The entire process of glycolysis does not take
Glycosome
13837173
Monocarboxylate transporter The monocarboxylate transporters, or MCTs, are a family of proton-linked plasma membrane transporters that carry molecules having one carboxylate group (monocarboxylates), such as lactate and pyruvate, across biological membranes. Lactate has long been considered a byproduct resulting from glucose breakdown through glycolysis during anaerobic metabolism. Glycolysis requires the coenzyme NAD, and reduces it to NADH. As a means of regenerating NAD to allow glycolysis to continue, lactate dehydrogenase catalyzes the conversion of pyruvate to lactate in the cytosol, oxidizing NADH to NAD. Lactate is then transported from the peripheral tissues to the liver. There it is reformed into
Monocarboxylate transporter
278160
aerobic (with oxygen) glycolysis and fed into the citric acid cycle. Although some more ATP is generated in the citric acid cycle, the most important product is NADH, which is made from NAD as the acetyl-CoA is oxidized. This oxidation releases carbon dioxide as a waste product. In anaerobic conditions, glycolysis produces lactate, through the enzyme lactate dehydrogenase re-oxidizing NADH to NAD+ for re-use in glycolysis. An alternative route for glucose breakdown is the pentose phosphate pathway, which reduces the coenzyme NADPH and produces pentose sugars such as ribose, the sugar component of nucleic acids. Fats are catabolised by hydrolysis
Metabolism
3967142
to regenerate RuBP. Five G3P molecules produce three RuBP molecules, using up three molecules of ATP. Since each molecule produces two G3P molecules, three molecules produce six G3P molecules, of which five are used to regenerate RuBP, leaving a net gain of one G3P molecule per three molecules (as would be expected from the number of carbon atoms involved). The regeneration stage can be broken down into steps. Thus, of six G3P produced, five are used to make three RuBP (5C) molecules (totaling 15 carbons), with only one G3P available for subsequent conversion to hexose. This requires nine ATP molecules
Light-independent reactions
17073959
yeast increases cellular respiration in the mitochondria by enhancing the translation of mitochondrial DNA that encodes for the complexes involved in the electron transport chain. When this electron transport chain is not as efficient, the unreduced oxygen molecules in the mitochondrial cortex may accumulate and begin to produce reactive oxygen species. It is important to note that both cancer cells as well as those cells with greater levels of mTORC1 both rely more on glycolysis in the cytosol for ATP production rather than through oxidative phosphorylation in the inner membrane of the mitochondria. Inhibition of mTORC1 has also been shown
MTORC1
17562949
a have a low affinity for oxygen. Anaerobic glycolysis leads to lactate overload, which the turtle buffers to some extent by increased shell and bone CaCO production. However, glycolysis is not efficient for ATP production, and in order to maintain an optimum ATP concentration, the turtle's brain reduces its ATP consumption by suppressing its neuronal activity and gradually releasing adenosine. This re-establishes the ATP consumption/production balance, which is then maintained by reducing ion conductance and releasing GABA. The decrease in neuronal activity renders the turtle comatose for the duration of anoxia. Another anoxia-tolerant animal that is commonly used as a
Mechanism of anoxic depolarization in the brain