Fatty acids are an important source of energy for many organisms. Excess glucose can be stored efficiently as fat. Triglycerides yield more than twice as much energy for the same mass as do carbohydrates or proteins. All cell membranes are built up of phospholipids, each of which contains two fatty acids. Fatty acids are also used for protein modification. The metabolism of fatty acids, therefore, consists of catabolic processes which generate energy and primary metabolites from fatty acids, and anabolic processes which create biologically important molecules from fatty acids and other dietary carbon sources. In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... Example of an unsaturated fat triglyceride. ... Lactose is a disaccharide found in milk. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a semipermeable lipid bilayer common to all living cells. ... Two schematic representations of a phospholipid. ... Anabolism is the aspect of metabolism that contributes to growth. ... Primary metabolites are a metabolite excreted during the growth phase. ... Anabolic is an adjective referring to processes of metabolism that result in growth of cells or organisms. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ...

Overview

• Lipolysis is carried out by lipases.
• Once freed from glycerol, free fatty acids can enter blood and muscle fiber by diffusion.
• Beta oxidation splits long carbon chains of the fatty acid into Acetyl CoA, which can eventually enter Krebs Cycle.

Briefly, β-oxidation or lipolysis of free fatty acids is as follows: Lipolysis is the breakdown of fat stored in fat cells. ... A lipase is an enzyme whose principal substrate is a lipid. ... Glycerol is a chemical compound with the formula HOCH2CH(OH)CH2OH. This colorless, odorless, viscous liquid is widely used in pharmaceutical formulations. ... Schematic demonstrating mitochondrial fatty acid beta-oxidation and effects of LCHAD deficiency Beta oxidation is the process by which fatty acids, in the form of Acetyl-CoA molecules, are broken down in the mitochondria to generate Acetyl-CoA, the entry molecule for the Krebs Cycle. ... Acetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. ... The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle) is a series of chemical reactions of central importance in all living cells that utilize oxygen as part of cellular respiration. ...

1. Dehydrogenation by Fatty Acyl-CoA Dehydrogenase, yielding 1 FADH₂
2. Hydration by Enoyl-CoA Hydratase
3. Dehydrogenation by 3-Hydroxyacyl-CoA dehydrogenase, yielding 1 NADH
4. Cleavage by Thiolase, yielding 1 Acetyl-CoA and a fatty acid that has now been shortened by 2 carbons

This cycle repeats until the FFA has been completely reduced to Acetyl-CoA or, in the case of Fatty acids with odd numbers of carbon atoms, Acetyl-CoA and 1 mol of Propionate per mol of fatty acid.

Fatty acids as an energy source

Fatty acids, stored as triglycerides in an organism, are an important source of energy because they are both reduced and anhydrous. The energy yield from a gram of fatty acids is approximately 9 kcal (39 kJ), compared to 4 kcal/g (17 kJ/g) for proteins and carbohydrates. Since fatty acids are non-polar molecules, they can be stored in a relatively anhydrous (water free) environment. Carbohydrates, on the other hand, are more highly hydrated. For example, 1 g of glycogen can bind approximately 2 g of water, which translates to 1.33 kcal/g (4 kcal/3 g). This means that fatty acids can hold more than six times the amount of energy. Put another way, if the human body relied on carbohydrates to store energy, then a person would need to carry 67.5 lb (31 kg) of hydrated glycogen to have the equivalent energy of 10 lb (5 kg) of fat. Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... As a general term, a substance is said to be anhydrous if it contains no water. ... BIC pen cap, about 1 gram. ... A calorie is a unit of measurement for energy. ... In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ... Electron micrograph of a section of a liver cell showing glycogen deposits as accumulations of electron dense particles (arrows). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... The pound (abbreviations: lb or, sometimes in the United States, #) is a unit of mass in a number of different systems, including various systems of units of mass that formed part of English units, Imperial units, and United States customary units. ... Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ...

Ruby-throated humming bird

Hibernating animals provide good example for utilizing fat reserve as fuel. For example bears go on hibernation for about 7 months and during this entire period the energy is derived from degradation of fat stores ImageMetadata File history File links Rubythroathummer65. ... ImageMetadata File history File links Rubythroathummer65. ...

The ruby-throated humming birds fly non stop between New England and West Indies (approximately a whopping distance of 2400 km)at a speed of 40 km/hr for 60 hours. This is possible only due to the stored fat.

Digestion

Fatty acids are usually ingested as triglycerides, which cannot be absorbed by the intestine. They are broken down into free fatty acids and monoglycerides by lipases with the help of bile salts. Most are absorbed as free fatty acids and 2-monoglycerides, but a small fraction is absorbed as free glycerol and as diglycerides. Once across the intestinal barrier, they are reformed into triglycerides and packaged into chylomicrons or liposomes, which are released in the lymph system and then into the blood. Eventually, they bind to the membranes of adipose cells or muscle, where they are either stored or oxidized for energy. The liver also acts as a major organ for fatty acid treatment, processing liposomes into the various lipoprotein forms, namely VLDL, LDL, IDL or HDL. Example of an unsaturated fat triglyceride. ... In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine (or colon). ... A computer-generated image of a type of pancreatic lipase (PLRP2) from the guinea pig. ... Bile is also another name for Belenus, a god in Brythonic mythology. ... Chylomicrons are large lipoprotein particles (having a diameter of 75 to 1,200nm) that are created by the absorptive cells of the small intestine. ... In mammals including humans, the lymphatic vessels (or lymphatics) are a network of thin tubes that branch, like blood vessels, into tissues throughout the body. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Adipocytes are cells present in adipose tissue, specialized in storing energy as fat. ... A top-down view of skeletal muscle Muscle (from Latin musculus little mouse [1]) is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... A lipoprotein is a biochemical assembly that contains both proteins and lipids. ... Very Low Density Lipoprotein (VLDL) is a lipoprotein subclass. ... Low-density lipoprotein (LDL) is a class of lipoprotein particles that varies in size (18-25 nm in diameter) and contents (while carrying fatty acid molecules in blood and around the body). ... Intermediate density lipoproteins are a class of lipoproteins formed from the degradation of very low density lipoproteins, constituted essentially of triacylglycerols and cholesterol esters. ... High-density lipoproteins (HDL) form a class of lipoproteins, varying somewhat in their size (8–11 nm in diameter), that carry cholesterol from the bodys tissues to the liver. ...

Degradation

See Fatty acid degradation

Three major steps are involved in the degradation of fatty acids. ...

Synthesis

See Fatty acid synthesis

Fatty acids are formed by the action of Fatty acid synthases from acetyl-CoA and malonyl-CoA precursors. ...

Regulation and control

Triacylglyceride lipase (TAG lipase), or hormone-sensitive lipase (HSL), is the enzyme that hydrolyses triacylglycerides to diacylglyceride, releasing free fatty acids from fats (lipolysis). HSL is regulated by the hormones insulin, glucagon, norepinephrine, and epinephrine. Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormone that regulates carbohydrate metabolism. ... Glucagon ball and stick model A microscopic image stained for glucagon. ... Norepinephrine (INN) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... Adrenaline redirects here. ...

Glucagon is associated with low blood glucose, and epinephrine is associated with increased metabolic demands. In both situations, energy is needed, and the oxidation of fatty acids is increased to meet that need. Glucagon, norepinephrine, and epinephrine bind to the G protein-coupled receptor, which activates adenylate cyclase to produce cyclic AMP. cAMP consequently activates protein kinase A, which phosphorylates (and activates) hormone-sensitive lipase. A Mu-opioid G protein-coupled receptor with its agonist Figure 1. ... Epinephrine binds its receptor, that associates with an heterotrimeric G protein. ... Structure of cAMP Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3-5-cyclic adenosine monophosphate) is a molecule that is important in many biological processes; it is derived from adenosine triphosphate (ATP). ...

When blood glucose is high, lipolysis is inhibited by insulin. Insulin activates protein phosphatase 2A, which dephosphorylates HSL, thereby inhibiting its activity. Insulin also activates the enzyme phosphodiesterase, which break down cAMP and stop the re-phosphorylation effects of protein kinase A. Protein phosphatases are enzymes that remove phosphate groups that have been attached to amino acid residues of proteins by protein kinases. ... A phosphodiesterase (PDE) is an enzyme that catalyzes the hydrolysis of phosphodiester bonds. ...

For the regulation and control of metabolic reactions involving fat synthesis, see lipogenesis. WHY DONT YALL HAVE ANYTHING? THIS IS THE MOST HELPFUL WEBISTE, SOMEBODY GET ON THIS NOW!! HAHAHHAH! What the hell is that! http://www. ...

See also

• Fatty acid synthase
• Essential fatty acid
• List of fatty acid metabolism disorders

Fatty acids are aliphatic acids fundamental to energy production and storage, cellular structure and as intermediates in the biosynthesis of hormones and other biologically important molecules. ... Essential fatty acids, or EFAs, are fatty acids that cannot be constructed within an organism from other components (generally all references are to humans) as there are no known biochemical pathways capable of producing them. ... It has been suggested that this article or section be merged with Inborn error of metabolism. ...

References

1. Berg, J.M., et al., Biochemistry. 5th ed. 2002, New York: W.H. Freeman. 1 v. (various pagings).
2. Dr.Mahmoud A.Z (own formula for ATP calculation) 2006

External links

• The chemical logic behind the metabolism of fatty acid

v • d • e Metabolism map

A polyunsaturated triglyceride. ... A few of the metabolic pathways in a cell. ... Fatty acids are an important source of energy for many organisms. ... Three major steps are involved in the degradation of fatty acids. ... Lipolysis is the breakdown of fat stored in fat cells. ... Schematic demonstrating mitochondrial fatty acid beta-oxidation and effects of LCHAD deficiency Beta oxidation is the process by which fatty acids, in the form of Acetyl-CoA molecules, are broken down in the mitochondria to generate Acetyl-CoA, the entry molecule for the Krebs Cycle. ... Fatty acids are formed by the action of Fatty acid synthases from acetyl-CoA and malonyl-CoA precursors. ... A few of the metabolic pathways in a cell. ... Image File history File links Metabolism_790px_partly_labeled. ... Glucuronate metabolism Pentose interconversion Inositol metabolism Cellulose and sucrose metabolism Starch and glycogen metabolism Other sugar metabolism Pentose phosphate pathway Glycolysis and Gluconeogenesis Amino sugars metabolism Small amino acid synthesis Branched amino acid synthesis Purine biosynthesis Histidine metabolism Aromatic amino acid synthesis Pyruvate decarboxylation Anaerobic respiration Fatty acid metabolism Urea cycle Aspartate amino acid group synthesis Porphyrins and corrinoids metabolism Citric acid cycle Glutamate amino acid group synthesis Pyrimidine biosynthesis  v • d • e  All pathway labels on this image are links, simply click to access the article. A high resolution labeled version of this image is available here.