Animals growth from single cells

Growth of Plants and Animals from Single Cells. 329... 

Cells, removed from animal tissues or whole animals, will continue to grow if supplied with nutrients and growth factors, allowing single cells to act as independent units that are able to divide by mitosis. Cell lines can... 

Other New Markets. Moving away from the automobile fuel market, ICI and Phillips Petroleum have developed single cell protein (SCP) products made by the growth of a microorganism that uses methanol as the sole source of carbon nutrient. These SCP s aim at the animal feed market as high protein additives in competition with skimmed milk powder and fish meal. If this process proves successful it offers a potential future additional consumption of methanol, although not in the same league as the possible fuel market. 

For dihydroorotate synthetase, the product of reaction 1, carbamoyl phosphate (CAP) is very unstable but is rapidly transformed by aspartate transcarbamoylase which is 50 times more active (per active site) than carbamoyl phosphate synthetase. High levels of carbamoyl aspartate (CA-asp) may be toxic, but this intermediate is rapidly consumed by the high dihydroorotase activity. Because the first three reactions are catalyzed by a single protein, the three enzyme active sites are expressed in a constant ratio under all conditions of growth this maintains CAP and CA-asp at low levels. For UMP synthase, OMP decarboxylase is far more active (per active site) than orotate PRTase, resulting in low cellular levels of the intermediate, OMP, which would otherwise be subject to enzymatic hydrolysis (in cells from higher animals). 

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