Lipids with its classification and detail.pptx

lipids and phospholipids

1. Lipids and its classification

2. Defination Lipids may be regarded as organic substances relatively insoluble in water, soluble in organic solvents( alcohol,ester etc ) actually or potentially related to fatty acids and utalized by the living cells.

3. Classification of lipids Lipids are classified into 3 types: Simple lipids. Complex lipids. Derived and miscellaneous lipids.

4. Simple lipids Simple lipids are the esters of fatty acids with alcohols. Types of simple lipids: simple lipids are mainly of two types Fats and oils Waxes Fats and oils: These are the esters of fatty acids with glycerol. The difference between fat and oil is only physical. Oil is liquid while fat is soild at room temperature.

5. Cont ….. Waxes: Esters of fatty acids with alcohols other than glycerol. These alcohols may be aliphatic or alicyclic. . Cetyl alcohol is most commonly found in waxes. . Waxes are used in preparation of candles, lubricants, cosmetics, ointments,polishes ete .

6. Complex lipids These are esters of fatty acids with alcohols containing additional groups such as phosphate, nitrogenous base, carbohydrates, protein etc. Types Phospholipids Glycolipids Lipoproteins

7. Cont ….. Phospholipid: They contain phosphoric acid and frequently a nitrogenous base.ThIs is in addition to alcohol and fatty acids. Phospholipids are subdivided into two types. Glycerophospholipids Sphingophospholipid Glycerophospholipids : These phospholipids contain Glycerol as the alcohol. Example : lecithin and cephalin Sphingophospholipids : Sphingosine is the alcohol in this group of phospholipid. Example: sphingomyelin

8. Cont ….. Glycolipids: These lipids contain a fatty acid, carbohydrates and nitrogenous base. The alcohol Is sphingosine,hence they are also called as glycosphingolipids Example: cerebrosides and gangliosides Lipoproteins: These are the macromolecular complexes of lipids with proteins. Other complex lipids: Sulfolipids,aminolipids and lipopolysaccharides are the other complex lipids.

9. Derived lipids These are the derivatives obtained on the hydrolysis of group 1 and group 2 lipids which possess the characteristics of lipids These includes glycerol and other alcohols, fatty acids , monoacylglycerols and diacylglycerols, lipids (fat) soluble vitamins,seroids horm ones, hydrocarbons and ketone bodies

10. Miscellaneous lipids These includes a large number of compounds processing the characteristics of lipids Example : Carotenoids,sqalene , hydrocarbons such as pantacosane ( in bee wax ), terpenes etc Neutral lipids The lipids which are uncharged are referred to as neutral lipids. These are monoacylglycerols , diacylglycerols and triacylyglycerol , cholesterol and cholesteryl esters.

11. Functions of lipids Energy storage:lipids are the Important source of energy. Digestion and absorption :lipids facilitate the digestion and absorption of the nutrients in the gut. Structural components : lipids are essential component of cell membrane, providing structural support and maintaining cell shape. Hormone regulation: lipids are involve in hormone production and regulation. Cushioning and protection : Lipids provide cushoining and protection to organs and tissues. Cell signalling :lipids Participate in cell signaling pathway. Modulation of immune response :Lipids are involve in the regulation of immune response and inflammation. Brain function :lipids partially cholesterol play an important role in brain function and development. Insulation : lipids help regulate body temperature and maintain insulation.

12. Fatty acids Defination Fatty acids are carboxylic acids with hydrocarbon side chain . They are the simplest form of lipids. Occurrence Fatty acids occur in the esterified form as major constituents of various lipids They are also present as free fatty acids. Fatty acids of animal origin are simpler in structure while fatty acids of plants origin contain group such as epoxy,keto,hydroxy and cyclopentane .

13. Difference between Saturated fatty acids These fatty acids contain only single C-C bond . In these fatty acids molecules are closely packed . Thesw fatty acids have strong attractive between chains. Saturated fatty acids have high melting point Saturated fatty acids are solid at room temperature. Unsaturated fatty acids These fatty acids contain two or more double C= C bonds. Non-linear chains inside these fatty acids do not allow molecules to pack closely. In these fatty acids,there is few attraction between chains. Unsaturated fatty acids have low melting point . Unsaturated fatty acids are liquid at room temperature.

14. Essential fatty acids Defination The fatty acids that cannot be synthesized by the body and, therefore, should be supplied in the diet are known as essential fatty acids (EFA) chemically,they are polyunsaturated fatty acids Biochemical basis of essentiality: linoleic acid and linolenic acid Are essential since humans lack the enzymes that can introduce double bonds beyond carbons 9 to 10

15. Cont … Function of EFA: Essential fatty acids are required for the membrane structure and function, transport of cholesterol. These are required for formation of lipoproteins They are essential for prevention of fatty liver. They are also needed for the synthesis of another important group of compounds,namely eicosanoids.

16. Cont … Deficiency of EFA: The deficiency of EFA results in phrynoderma or toad skin , characterized by the presence of horny eruptions on the posterior and lateral parts of limbs,on the back and buttocks of hair and poor wound healing. Conditionally essential fatty acids: Certain fatty acids that become essential under some developmenta l or disease conditions are referred as conditionally essential fatty acids. The most important among these is docosahexaenoic acid (DHA).

17. Cont … Isomerism in unsaturated fatty acids: Unsaturated fatty acids exhibit geometric isomerism depending on the orientation of the groups around the double bond axis. Cis configuration : . If the atom of acyl groups are present on the same side of the double bond,it is known as cis configuration. . Oleic acid is a Cis isomer.

18. Cont … Trans configuration : . If the groups occur on the opposite side it is known as trans configuration. . Elaidic acid is a trans isomer .

19. Cont …. Hydroxy fatty acids Some of the fatty acids are hydroxylated . B- hydroxybutyric acid, one of the ketone bodies produce in metabolism,is the simple example of hydroxy fatty acids. Cyclic fatty acids Fatty acids with cyclic stuctures are cyclic fatty acids.. Example :chaulmoogric acid found in chaulmoogra oil.

20. Trans fatty acid Trans fatty acids TFA posses double bonds and are formed during hydrogenation of natural oils Their small amount is also formed in human by the action of microorganisms on fat containing TFA Tfa are widely used in food industries. Margarine is the most commonly used TFA containing fat in food industries.

21. Triacylyglycerol Triacylyglycerol are the esters of glycerols With fatty acids The fats and oils are widely distributed in both plants and animals are chemicaly triacylyglycerol They are soluble in water and non-polar in character and commonly known as neutral fats

22. Fats as stored fuel Triacylglycerol are the most abundant group of lipids that primarily function as fuel reserves of animals The fat reserve of normal humans (men 20%,women25% by weight) Us sufficient to meet the body’s caloric requirements for 2-3 months

23. Fats primarily occure in adipose tissue: Adipocytes od adipose tissue-predominantly found in the subcutaneous layer and in the abdominal cavity are specialized for storage of triacylyglycerol The fat is stored in the form of glubules dispersed in the entire cytoplasm And surprisingly, triacylyglycerol are not the structural components od biological membranes

24. Structure of acylglycerols : Monoacylglycerols,diacylglycerols and triacylyglycerol respectively consisting of one,two and three molecules of fatty acids esterified to a molecule of glycerol are known

25. Classification of triacylyglycerol Simple triacylyglycerol : Contain the same type of fatty acids residue at all the three carbons. For example: tristearoyl glycerol or tristearin . Mixed triacylyglycerol : Are most common. . They contain 2 or 3 different types of fatty qcid residue. . Fatty acid attached to C1 is saturated, that attached to C2 is unsaturated while that on C3 can be either . triacylglyceroles are named according to placement of acyl radical on glycerol For example: 1,3-palmitoyl 2-linoleoyl glycerol

26. Properties od triacylyglycerol A few important properties of tryacylglycerols , which have biochemical relevance,are discussed bellow . Hydrolysis: Triacylyglycerol undergo stepwise enzymatic hydrolysis to finally liberate free fatty acids and glycerols . The process of hydrolysis, catalysed by lipase is important for digestion of fat in the gastrointestinal trac and fat mobilization from the adipose tissue. . Saponification: The hydrolysis of triacylyglycerols hy alkali to produce glycerol and soaps is known as saponification. .

27. Rancidity: Rancidy is the term used to represent the deterioration of fats and oils resulting in an unpleasant taste. Fats containing unsaturated fatty acids are more susceptible to rancidity. Rancidity occures when fats and oils are exposed to air, moisture,light,bacteria etc. Hydrolytic rancidity occures due to partial hydrolysis of triacylyglycerols by bacterial enzymes. Oxidative rancidity is due to oxidation of unsaturated fatty acids. This results in the formation of unpleasant products such as dicarboxylic acids, aldehydes,ketones etc. Rancid fats and oils are unsuitable for human consumption.

28. Antioxidants: . The substances which can prevent the occurrence of oxidation rancidity are known as antioxidants. . Trace amount of oxidants such as tocopherols (vitamin E), hydroquinone,gallic acid are added to the commercial preparation of fats and oils to prevent rancidity . Proyl Gallate,butylates hydroxyanisole (BHA) and butylated hydroxytoluene are the antioxidants used in food preservation. . Lipids peroxidation in vivo: . In the living cells,lipids undergo oxidation to produce peroxides and free radicals which can damage the tissue. . The free radicals are believed to causs inflammatory disease, ageing,cancer , atherosclerosis etc . It is fortunate that the cells possess antioxidants such as vitamin E,urate and superoxide dismutase to prevent in vivo lipid peroxidation.

29. These are complex or compound lipids containing phosphoric acid, in addition to fatty acid, nitrogenous base and alcohol. There are two classes of phospholipids Glycerophospholipids (or phosphoglyce -rides) that contain glycerol as the alcohol. Sphingophospholipids (or sphingomyelins ) that contain sphingosine as the alcohol. GLYCEROPHOSPHOLIPIDS : are the major lipids that occure in biological membranes. They consist of glycerol 3-phosphate esterified at its C1 and C2 with fatty acids. Usually , C1 contains a saturated fatty acid while C2 contain an unsaturated fatty acid. 1. PHOSPHATIDIC : This is the simplest phospholipid. It doesnot occur in good concentration In the tissues. Basically, phosphatidic acid is an intermediate in the synthesis of triacylglycerols and phospholipids. The other glycerophospholipids containing different base or other groups may be regarded as the derivatives of phosphatidic acid.

30. Phosphatidic acid This Photo by Unknown Author is licensed under CC BY

31. Lecithin (phosphatidylcholine) This Photo by Unknown Author is licensed under CC BY-SA-NC

32. Cephalin ( phosphatidylethanolamine )

33. Phosphatidylinositol

34. Plasmalogen

35. Cardiolipin

36. Sphingomyelin

37. Lencithins : These are the most abundant group of phospholipids in the cell membranes. Chemically, lecithin is a phosphatidic acid with choline as the base . Phosphatidylcholines represent the storage from of body choline. a) Dipalmitoyl Lecithin : is an important phosphatidylcholine found in lungs that act as a surfactant . b) Lysolecithin: is formed by removal of the fatty acid either at C1 or C2 of lecithin

38. Cephalins Ethanolamine is the nitrogenous base present in cephalins. Thus, lecithin and cephalin differ with regard to the base.

39. Phosphatidylserine The amino acid serine is present in the group of glycerophospholipids. Phosphatidylthreonine is also found certain tissue and plays a role in apoptosis

40. Plasmalogens When a fatty acid is attached by an ether linkage at C1 of glycerol in the glycerophospholipids, the resultant compound is plasmalogen. Phosphatidal -ethanolamine is the most important which is similar in structure to phosphatidylethanolamine but for the ether linkage. An unsaturated fatty acid occure at C1. Choline, inositol to give other plasmalogens.

41. Cardiolipin It is so named as it was first isolated from heart muscle. Structurally, a cardiolipin acid held by an additional glycerol through phosphate groups. It is an important component of inner mitochondrial member and essential for mitochondrial function. Cardiolipin is the only phospho-glyceride that possess antigenic propertities .

42. SPHINGOMYELINS Sphingosine is an amino alcohol present in sphingomyelin. They do not glycerol at all. Sphingosine is attached by an amid linkage to fatty acid to produce ceramide. The alcohol group of sphingosine is bound to phosphorylcholine in sphingomyelin structure. Sphingomyelin are important constituents of myelin and are found in good quantity in brain and nervous tissue.

43. FUNCTION OF PHOSPHOLIPIDS SOME FUNCTIONS ARE GIVEN BELOW: Arachidonic is an unsaturated fatty acid liberated from phospholipids, serves as a precursor for the synthesis of eicosanoids. Phospholipids participate in the reverse cholesterol transport and thus help in the removel of cholesterol from the body. Phospholipids act as surfactants. For instance, dipalmitoyl phosphatidylcholine s an important lung surfactant. Cephalins, an important group of phospholipids participate in blood clothing. Phosphatidylinositol is the source of second messenger-inositol triphosphate and diacylglyceol , that are involed in the actionof some hormones.

44. Glycolipids Glycolipids are important constituents of the cell membrane and nervous tissue. They occurs as cell surface carbohydrate to from glycocalyx in plasma membranes. Cerebrosides are the simplest form of glycolipids They contain a ceramide and one and more sugars. Galactocerebroside and glucocerebroside are the most important glycolipids. Gangliosides are predominantly found in ganglions are the most complex from of glycosphingolipids. They are the derivatives of cerebrosides and contain one or more molecules of N-acetylneuraminic acid , the most important sialic acid. The gangliosides , GM2That accumulate in Tay-Sachs disease is represent next. Globosides a type of glycolipid with two or more sugars Linked to ceramide the sugars usually present are Glucose and galactose. Lactosylceramide is present in Erythrocyte membrane. This Photo by Unknown Author is licensed under CC BY-SA-NC