Fats and Other Lipids - Diet and Health - NCBI Bookshelf
Lipid: Lipid, any of a diverse group of organic compounds including fats, oils, hormones, and certain components of membranes that are grouped together. Some examples of the types of lipids are: neutral, saturated, (poly/mono) unsaturated fats reactions creating ester linkages that link the fatty acid carboxyl groups to the There are two different types of fatty acids, saturated and unsaturated. Fats, Steroids, and Other Examples of Lipids The structure of the fatty acids determines whether or not the fat is considered saturated or.
Omega-3 and omega-6 fatty acids have at least two cis-unsaturated bonds, which gives them a curved shape. What makes a fatty acid omega-3 or omega-6? The naming of these molecules is based on their structure. Omega-6 fatty acids are defined analogously, with the first double bond located between the sixth and seventh carbons from the omega end. Image of alpha-linoleic acid ALAshowing its curled shape due to its three cis double bonds. Omega-3 and omega-6 fatty acids play a number of different roles in the body.
They are precursors starting material for the synthesis of a number of important signaling molecules, including ones that regulate inflammation and mood. Omega-3 fatty acids in particular may reduce the risk of sudden death from heart attacks, decrease triglycerides in the blood, lower blood pressure, and prevent the formation of blood clots.
However, fats are essential to the body and have a number of important functions. For instance, many vitamins are fat-soluble, meaning that they must be associated with fat molecules in order to be effectively absorbed by the body. Fats also provide an efficient way to store energy over long time periods, since they contain over twice as much energy per gram as carbohydrates, and they additionally provide insulation for the body. Like all the other large biological molecules, fats in the right amounts are necessary to keep your body and the bodies of other organisms functioning correctly.
Waxes Waxes are another biologically important category of lipids. Wax covers the feathers of some aquatic birds and the leaf surfaces of some plants, where its hydrophobic water-repelling properties prevent water from sticking to, or soaking into, the surface. Image of shiny leaf surface covered with wax. Structurally speaking, waxes typically contain long fatty acid chains connected to alcohols by ester linkages, although waxes produced by plants often have plain hydrocarbons mixed in as well 6 6.
Phospholipids What keeps the watery goo cytosol inside of your cells from spilling out?
Cells are surrounded by a structure called the plasma membrane, which serves as a barrier between the inside of the cell and its surroundings. Specialized lipids called phospholipids are major components of the plasma membrane. Like fats, they are typically composed of fatty acid chains attached to a backbone of glycerol.
Instead having three fatty acid tails, however, phospholipids generally have just two, and the third carbon of the glycerol backbone is occupied by a modified phosphate group. Different phospholipids have different modifiers on the phosphate group, with choline a nitrogen-containing compound and serine an amino acid being common examples. Different modifiers give phospholipids different properties and roles in a cell.
Lipid - Wikipedia
Structure of a phospholipid, showing hydrophobic fatty acid tails and hydrophilic head including ester linkages, glycerol backbone, phosphate group, and attached R group on phosphate group. A bilayered membrane consisting of phospholipids arranged in two layers, with their heads pointing out and their tails sandwiched in the middle, is also shown.
Once your intestinal cells absorb the fatty acids and monoglycerides, they once again come together as a triglyceride and are packaged into a unit called a chylomicron.
The triglyceride-rich chylomicron then moves from your intestinal cell to lymph vessels and then into your bloodstream.
Metabolism Once in your bloodstream, triglycerides and their component fatty acids have several potential fates.
Triglycerides can travel as is to your adipose tissue for storage, or they can move to the surface of cells throughout your body. In the latter case, additional lipase enzymes release the individual fatty acids from the triglyceride. These fatty acids then might incorporate into cell membranes or help create other lipids.
They can also enter the cell and form new triglyceride molecules for fat storage within non-adipose tissues. They accomplish this by being exposed to the extracellular face of the cell membrane after the inactivation of flippases which place them exclusively on the cytosolic side and the activation of scramblases, which scramble the orientation of the phospholipids. After this occurs, other cells recognize the phosphatidylserines and phagocytosize the cells or cell fragments exposing them.
Acyl-carnitines are involved in the transport and metabolism of fatty acids in and out of mitochondria, where they undergo beta oxidation.
What Is the Difference Between a Fatty Acid and a Triglyceride?
Polyprenol phosphate sugars and polyprenol diphosphate sugars function in extra-cytoplasmic glycosylation reactions, in extracellular polysaccharide biosynthesis for instance, peptidoglycan polymerization in bacteriaand in eukaryotic protein N- glycosylation. The process of lipid metabolism synthesizes and degrades the lipid stores and produces the structural and functional lipids characteristic of individual tissues. Biosynthesis[ edit ] In animals, when there is an oversupply of dietary carbohydrate, the excess carbohydrate is converted to triglycerides.
This involves the synthesis of fatty acids from acetyl-CoA and the esterification of fatty acids in the production of triglycerides, a process called lipogenesis. The acyl chains in the fatty acids are extended by a cycle of reactions that add the acetyl group, reduce it to an alcohol, dehydrate it to an alkene group and then reduce it again to an alkane group. The enzymes of fatty acid biosynthesis are divided into two groups, in animals and fungi all these fatty acid synthase reactions are carried out by a single multifunctional protein,  while in plant plastids and bacteria separate enzymes perform each step in the pathway.
The synthesis of unsaturated fatty acids involves a desaturation reaction, whereby a double bond is introduced into the fatty acyl chain. For example, in humans, the desaturation of stearic acid by stearoyl-CoA desaturase-1 produces oleic acid.
In animals and archaeathe mevalonate pathway produces these compounds from acetyl-CoA,  while in plants and bacteria the non-mevalonate pathway uses pyruvate and glyceraldehyde 3-phosphate as substrates. Here, the isoprene units are joined together to make squalene and then folded up and formed into a set of rings to make lanosterol.
Structural Biochemistry/Lipids/Fatty Acids - Wikibooks, open books for an open world
For the most part, fatty acids are oxidized by a mechanism that is similar to, but not identical with, a reversal of the process of fatty acid synthesis. That is, two-carbon fragments are removed sequentially from the carboxyl end of the acid after steps of dehydrogenationhydrationand oxidation to form a beta-keto acidwhich is split by thiolysis.
Hence the citric acid cycle can start at acetyl-CoA when fat is being broken down for energy if there is little or no glucose available.
The energy yield of the complete oxidation of the fatty acid palmitate is ATP. Nutrition and health[ edit ] Most of the fat found in food is in the form of triglycerides, cholesterol, and phospholipids.
Some dietary fat is necessary to facilitate absorption of fat-soluble vitamins ADEand K and carotenoids. Most vegetable oils are rich in linoleic acid safflowersunflowerand corn oils. Alpha-linolenic acid is found in the green leaves of plants, and in selected seeds, nuts, and legumes in particular flaxrapeseedwalnutand soy.
Fats that are good for you can be turned into trans fats by overcooking.
- Structural Biochemistry/Lipids/Fatty Acids
- Structural Biochemistry/Organic Chemistry/Lipids
The Nutrition Source, a website maintained by the Department of Nutrition at the Harvard School of Public Healthsummarizes the current evidence on the impact of dietary fat: