fatty acids that cannot be synthesized within an organism are referred to as
non-essential fatty acids
title: Fatty acid text: Fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually not found in organisms, but instead as three main classes of esters: triglycerides, phospholipids, and cholesterol esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells. The concept of fatty acid ("acide gras") was introduced by title: Fatty acid text: glycol, diethylene glycol, and polyethylene glycol are consumed in food, or used for personal care and water treatment, or used as synthetic lubricants or fluids for metal working. Fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually not found in organisms, but instead as three main classes of esters: triglycerides, phospholipids, and cholesterol esters. In any of these forms, fatty title: Fatty acid text: tissues) are distributed to cells to serve as a fuel for muscular contraction and general metabolism. They are broken down to CO and water by the intra-cellular mitochondria, releasing large amounts of energy, captured in the form of ATP through beta oxidation and the citric acid cycle. Fatty acids that are required for good health but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids. There are two series of essential fatty acids: one has a double bond three carbon atoms away from the methyl end; the other title: Phospholipid-derived fatty acids text: saturated fatty acids ("e.g." 15:0), branched-chain fatty acids (mainly iso/anetiso and 10-methyl) and cyclopropane fatty acids ("e.g." 19:0 cyclo ω7c) are mostly synthesized by bacteria. The monounsaturated fatty acid, 16:1 ω5c, is mostly synthesized by Arbuscular mycorrhizal fungi (AMF) and the polyunsaturated fatty acid, 18:2 ω6c (Linoleic acid), is mostly synthesized by Ectomycorrhizal fungi. The basic premise is that as individual organisms (especially bacteria and fungi) die, phospholipids are rapidly degraded and the remaining phospholipid content of the sample is assumed to be from living organisms. As the phospholipids of different groups of bacteria and fungi contain a variety of title: Nonvolatile acid text: Nonvolatile acid A nonvolatile acid (also known as a fixed acid or metabolic acid) is an acid produced in the body from sources other than carbon dioxide, and is not excreted by the lungs. They are produced from e.g. an incomplete metabolism of carbohydrates, fats, and proteins. All acids produced in the body are nonvolatile except carbonic acid, which is the sole volatile acid. Common nonvolatile acids in humans are lactic acid, phosphoric acid, sulfuric acid, acetoacetic acid, and beta-hydroxybutyric acid. Humans produce about 1–1.5 mmoles of H per kilogram per day. The nonvolatile acids are excreted by the kidneys.