Structural Biochemistry/Lipids/Cholesterol - Wikibooks, open books for an open world
Cholesterol is an essential component of cell membranes, of brain and nerve cells, and of bile, which helps the body absorb fats and fat-soluble vitamins. Fats and cholesterol can help keep our bodies healthy or they can promote Overweight, obesity, and high intake of saturated fats are major risk factors for elevated LDL ('bad') cholesterol . The Relationship Between Fat and Cholesterol. Cholesterol is a lipid with a unique structure consisting of four fused differs from phospholipids, it disrupts the normal reactions between fatty acid chains. . The American Heart Association recommends a daily intake of less that mg of.
If a fatty acid contains a double bond, there is the possibility of either a cis or trans geometric isomerismwhich significantly affects the molecule's configuration. Cis-double bonds cause the fatty acid chain to bend, an effect that is compounded with more double bonds in the chain.
Three double bonds in carbon linolenic acidthe most abundant fatty-acyl chains of plant thylakoid membranes, render these membranes highly fluid despite environmental low-temperatures,  and also makes linolenic acid give dominating sharp peaks in high resolution C NMR spectra of chloroplasts.
This in turn plays an important role in the structure and function of cell membranes. Docosahexaenoic acid is also important in biological systems, particularly with respect to sight. Fatty esters include important biochemical intermediates such as wax estersfatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines. The fatty amides include N-acyl ethanolaminessuch as the cannabinoid neurotransmitter anandamide.
Glycerolipids are composed of mono- di- and tri-substituted glycerols the best-known being the fatty acid triesters of glycerol, called triglycerides. The word "triacylglycerol" is sometimes used synonymously with "triglyceride". In these compounds, the three hydroxyl groups of glycerol are each esterified, typically by different fatty acids. Because they function as an energy store, these lipids comprise the bulk of storage fat in animal tissues.
The hydrolysis of the ester bonds of triglycerides and the release of glycerol and fatty acids from adipose tissue are the initial steps in metabolizing fat. Examples of structures in this category are the digalactosyldiacylglycerols found in plant membranes  and seminolipid from mammalian sperm cells. In addition to serving as a primary component of cellular membranes and binding sites for intra- and intercellular proteins, some glycerophospholipids in eukaryotic cells, such as phosphatidylinositols and phosphatidic acids are either precursors of or, themselves, membrane-derived second messengers.
The major sphingoid base of mammals is commonly referred to as sphingosine. Ceramides N-acyl-sphingoid bases are a major subclass of sphingoid base derivatives with an amide -linked fatty acid.
The fatty acids are typically saturated or mono-unsaturated with chain lengths from 16 to 26 carbon atoms. Examples of these are the simple and complex glycosphingolipids such as cerebrosides and gangliosides.
Sterol lipids[ edit ] Sterol lipids, such as cholesterol and its derivatives, are an important component of membrane lipids,  along with the glycerophospholipids and sphingomyelins.
The steroidsall derived from the same fused four-ring core structure, have different biological roles as hormones and signaling molecules. The eighteen-carbon C18 steroids include the estrogen family whereas the C19 steroids comprise the androgens such as testosterone and androsterone.
The C21 subclass includes the progestogens as well as the glucocorticoids and mineralocorticoids. Structures containing greater than 40 carbons are known as polyterpenes. Fat is a necessary component of a healthy diet. Fat is essential in the absorption of fat-soluble vitamins A, D, E and K and also makes up parts the hormones that regulate important body functions.
Lipids (article) | Macromolecules | Khan Academy
Dietary fat provides essential fatty acids, such as linolenic omega-3 and linoleic omega-6 acids, which the body cannot produce on its own. Essential fatty acids are necessary for brain and eye development in infants and children and the maintenance of healthy skin in children and adults.
Dietary fat may improve the taste of food, aid in cooking, and increase satiety. Yet, eating too much fat may lead to increased weight, as it has more than twice as many calories per ounce as sugar, starch or protein. Consuming fatty foods in excess may increase total and LDL cholesterol levels, while increasing the risk of heart disease and some forms of cancer. Types of Fat Are all fats the same?
There is not a single type of fat. Scientific term referring to fat, cholesterol and other fat-like substances.Fats - biochemistry
Scientific name for the main form of fat found in in the body and in foods. Most of the fat in the body is stored as triglycerides, but triglycerides circulate in the blood as well. Triglycerides are made of three fatty acids and one glycerol molecule. These three fatty acids may include any combination of saturated fatty acids, monounsaturated fatty acids MUFAsand polyunsaturated fatty acids PUFAs.
Triglycerides in the blood stream trigger the liver to make more cholesterol, so high triglyceride levels are often associated with high levels of total and LDL cholesterol. Usually solid at room temperature, saturated fats have all of the hydrogen atoms they can hold saturated with hydrogen. Saturated fats are primarily from animal products, but are also found in tropical plant oils, such as coconut and palm as well as other plant based foods, though in smaller amounts.
This process can be beneficial because hormones and antibodies can transport proteins use this method. However, on the downside the pathway is also available to viruses and toxins as a means of entry into the cell.
Cholesterol: Is it a Lipid?
Hypercholesterolemia is a condition when there is an extremely high level of cholesterol in the body. When too much LDL circulates the blood cell, it can build up on the inner walls of arteries that feed the heart and brain, and therefore, cause the clogging of the arteries.
The health significance is that they are prone to cardiovascular diseases. If a clot forms and blocks the narrowed artery, a series of cardiovascular diseases such as hypertension, myocardial infarction, arteriosclerosis, angina pectoris, heart attack or stroke can result.