how many molecules of atp does anaerobic metabolism produce
Cellular respiration Aerobic metabolism is up to 15 times more efficient than anaerobic metabolism (which yields 2 molecules ATP per 1 molecule glucose). 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.
Metabolic pathway The rate of turnover in a metabolic pathway, otherwise known as the metabolic flux, is regulated based on the stoichiometric reaction model, the utilization rate of metabolites, and the translocation pace of molecules across the lipid bilayer.[20] The regulation methods are based on experiments involving 13C-labeling, which is then analyzed by Nuclear Magnetic Resonance (NMR) or gas chromatography-mass spectrometry (GC-MS)-derived mass compositions. The aforementioned techniques synthesize a statistical interpretation of mass distribution in proteinogenic amino acids to the catalytic activities of enzymes in a cell.[21]
Exhalation Exhaled air is rich in carbon dioxide, a waste product of cellular respiration during the production of energy, which is stored as ATP. Exhalation has a complementary relationship to inhalation which together make up the respiratory cycle of a breath.
Flavin adenine dinucleotide FAD has a more positive reduction potential than NAD+ and is a very strong oxidizing agent. The cell utilizes this in many energetically difficult oxidation reactions such as dehydrogenation of a C-C bond to an alkene. FAD-dependent proteins function in a large variety of metabolic pathways including electron transport, DNA repair, nucleotide biosynthesis, beta-oxidation of fatty acids, amino acid catabolism, as well as synthesis of other cofactors such as CoA, CoQ and heme groups. One well-known reaction is part of the citric acid cycle (also known as the TCA or Krebs cycle); succinate dehydrogenase (complex II in the electron transport chain) requires covalently bound FAD to catalyze the oxidation of succinate to fumarate by coupling it with the reduction of ubiquinone to ubiquinol.[11] The high-energy electrons from this oxidation are stored momentarily by reducing FAD to FADH2. FADH2 then reverts to FAD, sending its two high-energy electrons through the electron transport chain; the energy in FADH2 is enough to produce 1.5 equivalents of ATP[18] by oxidative phosphorylation. There are also redox flavoproteins that non-covalently bind to FAD like Acetyl-CoA-dehydrogenases which are involved in beta-oxidation of fatty acids and catabolism of amino acids like leucine (isovaleryl-CoA dehydrogenase), isoleucine, (short/branched-chain acyl-CoA dehydrogenase), valine (isobutyryl-CoA dehydrogenase), and lysine (glutaryl-CoA dehydrogenase).[19] Additional examples of FAD-dependent enzymes that regulate metabolism are glycerol-3-phosphate dehydrogenase (triglyceride synthesis) and xanthine oxidase involved in purine nucleotide catabolism.[20] There are other noncatalytic roles that FAD can play in flavoproteins such as structural roles, or involved in blue-sensitive light photoreceptors that regulate biological clocks and development, generation of light in bioluminescent bacteria.[19]