Editing Biochemistry (section)

====Gluconeogenesis====
{{Main|Gluconeogenesis}}
In [[vertebrate]]s, vigorously contracting [[skeletal muscle]]s (during weightlifting or sprinting, for example) do not receive enough oxygen to meet the energy demand, and so they shift to [[Fermentation (biochemistry)|anaerobic metabolism]], converting glucose to lactate.
The combination of glucose from noncarbohydrates origin, such as fat and proteins. This only happens when [[glycogen]] supplies in the liver are worn out. The pathway is a crucial reversal of [[glycolysis]] from pyruvate to glucose and can use many sources like amino acids, glycerol and [[Krebs Cycle]]. Large scale protein and fat [[catabolism]] usually occur when those suffer from starvation or certain endocrine disorders.<ref>{{Cite book| url=https://www.oxfordreference.com/view/10.1093/acref/9780198714378.001.0001/acref-9780198714378| isbn=9780198714378| title=A Dictionary of Biology| date=17 September 2015| publisher=Oxford University Press| access-date=29 April 2020| archive-date=10 July 2020| archive-url=https://web.archive.org/web/20200710005409/https://www.oxfordreference.com/view/10.1093/acref/9780198714378.001.0001/acref-9780198714378| url-status=live}}</ref> The [[liver]] 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 into the bloodstream is called the [[Cori cycle]].<ref>[[#Fromm|Fromm and Hargrove]] (2012), pp. 183–194.</ref>