Lipids are defined as compounds that do not dissolve in water, which is extracted from living organisms using a weak solvent polarity solvents nonopolar. This definition is based on physical properties, in contrast to the definition of protein, carbohydrates and nucleic acids based on their chemical structure. The term lipid mencakupberbagai variety of compounds of different structure.
There are some functions of lipids include:
• As a structural constituent of cell membranes
In this case the lipid acts as a barrier to cells and regulate the flow of materials.
• As energy reserves
Lipids are stored as adipose tissue
• As the hormones and vitamins
Hormones regulate communication between cells, while vitamin helps the regulation of biological processes
Types of lipids
There are several types of lipids are:
• Fatty acids, composed of saturated fatty acids and unsaturated fatty acids
• glycerides, consisting of neutral glycerides and fosfogliserida
• Lipid complex, consisting of lipoproteins and glycolipids
• Non-glycerides, comprising sfingolipid, steroids and night
Lipids in the human diet is the main triacylglycerol, sterols, and membrane phospholipids derived from animals and plants. process of forming lipid metabolism and lipid deposits degrade and produce the characteristic structure and function of lipids in certain tissues.
Many types of lipids that are amfifilik, meaning consists of two parts, namely a nonpolar hydrocarbon regions and polar or ionic regions on both. The term amfifilik amfifatik replaces the previously used term.
Lipids can be classified into two major parts:
Ø Lipid based on their classification:
1. Lipid simple: as esters. Fat and various alcohols, eg fat or oil and wax (wax)
2. Lipid complex (combined): as.lemak esters having other groups in addition to alcohol and as. fat, eg fosfolifid, glikolofid, and lipoprotein
3. Lipid derivatives: compounds produced by the hydrolysis of lipids, as.lemak eg, glycerol, fatty aldehydes, ketones, hydrocarbons, sterols, fat-soluble vitamins and some hormones
Ø Lipid based chemical properties of lipids can also be divided into 2 groups:
1. Lipids that can be hydrolyzed, Contonya fats and oils
2. That can not be hydrolyzed lipids, sterols and terpenes Contonya
Lipids have important biological role or function in life, among which are the following:
1. As fuel
2. As the cell membrane forming materials
3. As an insulator (protective). For example, thermal and electrical insulation
Fatty acids are stored as triacylglycerol in adipose tissue is the main energy source for a variety of networks when the availability slukosa thinning. Stress, long practice, and famine caused depot lipid mobilization. Triacylglycerol hydrolyzed if the so-called hormone-sensitive lipase, and fatty acids are released into the circulation. Non-esterified fatty acid that binds to serum albumin, passing through the circulation into tissues. By binding to fatty acids, albumin facilitate their inclusion in the circulation and minimize reaction during pengakutan detergennya.
Fat oxidation occurs in three steps, called activation, tranfor into the mitochondria, and oxidation to acetyl-Co-A. In general, the influx of fatty acids into metabolic pathways preceded by conversion into derivatives of coenzyme A (CoASH). Original derivative is called alkanoyl-CoA or alkenoil-CoA, which is in the form of this fatty acid is said to tel; ah activated. Activation of fatty acid led to the formation of thioesters to fatty acids and CoA. This process simultaneously with the hydrolysis of ATP to AMP.
Fatty acids in nature can be divided into 2 groups:
1. Saturated fatty acids (saturated acid)
Example: as.palmitat, strearat acid, and capric acid
2. Unsaturated fatty acids (unsaturated acid)
Example: oleic acid, linoleic acid and linolenic acid
In addition to the above two categories, we found two other groups:
1. Branched fatty acids (branched chain acid)
2. Cyclic fatty acid (cyclic acid)
Fat has a very important function biologiyang, namely:
Ø fats in food, function:
1. Energy carriers
2. Mediator for vitamins that are fat soluble
3. The source for essential fatty acids
Ø fat in the body, function:
1. Largest energy reserves
2. Carbon source for a variety of synthesis that occurs in the body
3. Temperature and electrical insulator
4. Mechanical bearings