Editing Bioenergetics (section)

==Examples of major bioenergetic processes==
* [[Glycolysis]] is the process of breaking down glucose into [[pyruvate]], producing two molecules of ATP (per 1 molecule of glucose) in the process.<ref> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 544. </ref> When a cell has a higher concentration of ATP than ADP (i.e. has a high [[energy charge]]), the cell cannot undergo glycolysis, releasing energy from available glucose to perform biological work. Pyruvate is one product of glycolysis, and can be shuttled into other metabolic pathways (gluconeogenesis, etc.) as needed by the cell. Additionally, glycolysis produces [[reducing equivalents]] in the form of [[Nicotinamide adenine dinucleotide|NADH]] (nicotinamide adenine dinucleotide), which will ultimately be used to donate electrons to the [[Electron Transport Chain|electron transport chain]].
* [[Gluconeogenesis]] is the opposite of glycolysis; when the cell's energy charge is low (the concentration of ADP is higher than that of ATP), the cell must synthesize glucose from carbon- containing biomolecules such as proteins, amino acids, fats, pyruvate, etc.<ref> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 568. </ref> For example, proteins can be broken down into amino acids, and these simpler carbon skeletons are used to build/ synthesize glucose.
* [[Citric acid cycle|The citric acid cycle]] is a process of [[cellular respiration]] in which [[Acetyl-CoA|acetyl coenzyme A]], synthesized from [[Pyruvate dehydrogenase complex|pyruvate dehydrogenase]], is first reacted with [[oxaloacetate]] to yield [[citrate]].<ref> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 633. </ref> The remaining eight reactions produce other carbon-containing metabolites. These metabolites are successively oxidized, and the free energy of oxidation is conserved in the form of the reduced coenzymes [[Flavin adenine dinucleotide|FADH<sub>2</sub>]] and [[Nicotinamide adenine dinucleotide|NADH]].<ref> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 640. </ref> These reduced electron carriers can then be re-oxidized when they transfer electrons to the [[electron transport chain]].
* [[Ketosis]] is a metabolic process where the body prioritizes ketone bodies, produced from fat, as its primary fuel source instead of glucose.<ref>Masood W, Annamaraju P, Khan Suheb MZ, et al. Ketogenic Diet. [Updated 2023 Jun 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499830/ {{Webarchive|url=https://web.archive.org/web/20210614082923/https://www.ncbi.nlm.nih.gov/books/NBK499830/ |date=2021-06-14 }}</ref> This shift often occurs when glucose levels are low: during prolonged fasting, strenuous exercise, or specialized diets like ketogenic plans, the body may also adopt ketosis as an efficient alternative for energy production.<ref>Devrim-Lanpir, Aslı, Lee Hill, and Beat Knechtle. 2021. "Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review" Nutrients 13, no. 2: 491. https://doi.org/10.3390/nu13020491</ref> This metabolic adaptation allows the body to conserve precious glucose for organs that depend on it, like the brain, while utilizing readily available fat stores for fuel.
* [[Oxidative phosphorylation]] and the [[electron transport chain]] is the process where reducing equivalents such as [[Nicotinamide adenine dinucleotide phosphate|NADPH]], [[Flavin adenine dinucleotide|FADH<sub>2</sub>]] and [[Nicotinamide adenine dinucleotide|NADH]] can be used to donate electrons to a series of redox reactions that take place in electron transport chain complexes.<ref name="AutoRefD"> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 731. </ref><ref> Nelson, David L., Cox, Michael M. ''Lehninger: Principles of Biochemistry.'' New York: W.H. Freeman and Company, 2013. Sixth ed., pg 734. </ref> These redox reactions take place in enzyme complexes situated within the mitochondrial membrane. These redox reactions transfer electrons "down" the electron transport chain, which is coupled to the [[Chemiosmosis|proton motive force]]. This difference in proton concentration between the mitochondrial matrix and inner membrane space is used to drive ATP synthesis via [[ATP Synthase|ATP synthase]].
* [[Photosynthesis]], another major bioenergetic process, is the metabolic pathway used by plants in which solar energy is used to synthesize glucose from carbon dioxide and water. This reaction takes place in the [[chloroplast]]. After glucose is synthesized, the plant cell can undergo [[photophosphorylation]] to produce ATP.<ref name="AutoRefD" />