Biochemistry lecture notes lipids
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Lipids are organic compounds that include fats, oils, waxes, and steroids. They are insoluble in water but soluble in nonpolar solvents. The main types of lipids are fatty acids, triglycerides, phospholipids, sterols, and prostaglandins. Fatty acids are the building blocks of lipids and contain long hydrocarbon chains that can be saturated or unsaturated. Triglycerides are composed of fatty acids bound to a glycerol molecule and are the main constituents of fats and oils. Phospholipids and sterols such as cholesterol are important components of cell membranes.
![• Shorter fatty acids usually have lower melting points than longer ones
(stearic acid [18C] = 70ºC, palmitic acid [16C] = 63ºC)
FATTY ACIDS – Melting Property
• The cis-double bonds in
unsaturated fatty acids put an
inflexible “kink” in the carbon
chain, preventing the molecules
from packing together as tightly
as saturated fatty acids do.](https://image.slidesharecdn.com/biochemistrylecturenoteslipids-200427035759/85/Biochemistry-lecture-notes-lipids-14-320.jpg)
Biochemistry lecture notes lipids
- 1. LIPIDS Dr.B.RENGESH | M.Tech., Ph.D. Associate Professor, Department of Pharmaceutical Technology, Mahendra Engineering College (Autonomous), Namakkal District, Tamil Nadu, India
- 2. v Lipids are organic compounds formed mainly from alcohol and fatty acids combined together by ester linkage. v Lipids are biological molecules that are insoluble in water but soluble in nonpolar solvents (ether, chloroform, benzene, acetone). v Lipids are the waxy, greasy, or oily compounds found in plants and animals.
- 3. v They are more palatable and storable to unlimited amount compared to carbohydrates. v They have a high-energy value (25% of body needs) and they provide more energy per gram than carbohydrates and proteins but carbohydrates are the preferable source of energy. v Supply the essential fatty acids that cannot be synthesized by the body. v Supply the body with fat-soluble vitamins (A, D, E and K). v They are important constituents of cell membrane and nervous system. BIOLOGICAL IMPROTANCE OF LIPIDS
- 4. v Stored lipids “depot fat” is stored in all animal cells act as • A store of energy. • A pad for the internal organs to protect them from outside shocks. • A subcutaneous thermal insulator against loss of body heat. v Lipids provide bases for dealing with diseases such as obesity, atherosclerosis, lipid-storage diseases, essential fatty acid deficiency, respiratory distress syndrome, BIOLOGICAL IMPROTANCE OF LIPIDS
- 5. CLASSIFICATION OF LIPIDS contain esters contain 2 types of components (a fatty acid & an alcohol) contain > 2 types of components (a fatty acid, an alcohol & others)
- 6. v a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. FATTY ACIDS
- 7. Properties: • The long, nonpolar hydrocarbon tails of fatty acids are responsible for most of the fatty or oily characteristics of lipids. • The carboxyl (COOH) group is hydrophilic (polar) under basic conditions, such as physiological pH (7.4) • Fatty Acid Micelles FATTY ACIDS Micelles are important in the transport of insoluble lipids in the blood
- 8. Characteristics: • The chain length ranges from 4 to 30 carbons; 12-24 is most common. • The chain is typically linear, and usually contains an even number of carbons • The many fatty acids which occur naturally arise primarily through variation of chain length and degree of saturation • There may be one double bond or many, up to six in important fatty acids. FATTY ACIDS
- 9. Characteristics: • When double bonds occur they are almost always cis. If there is more than 1 double bond, they occur at three-carbon intervals FATTY ACIDS e.g., -C=C-C-C=C-. This is called divinylmethane pattern.
- 10. • If without double bonds: Saturated Fatty Acids • If with double bonds: Unsaturated Fatty Acids o 1 double bond: Monounsaturated fatty acids o 2 or more double bonds: Polyunsaturated fatty acids FATTY ACIDS - Classification based on number of double bonds & Nomenclature
- 11. List of some Saturated Fatty Acids Common Name Systematic Name Structural Formula Lipid Numbers Propionic acid Propanoic acid CH3CH2COOH C3:0 Butyric acid Butanoic acid CH3(CH2)2COOH C4:0 Valeric acid Pentanoic acid CH3(CH2)3COOH C5:0 Caproic acid Hexanoic acid CH3(CH2)4COOH C6:0 Caprylic acid Octanoic acid CH3(CH2)6COOH C8:0 Capric acid Decanoic acid CH3(CH2)8COOH C10:0 Myristic acid Tetradecanoic acid CH3(CH2)12COOH C14:0 Palmitic acid Hexadecanoic acid CH3(CH2)14COOH C16:0 Stearic acid Octadecanoic acid CH3(CH2)16COOH C18:0
- 12. List of some Mono-Unsaturated Fatty Acids Common Name Chemical Name Lipid Numbers Myristoleic acid cis-Tetradec-9-enoic acid 14:1 (n-5) Palmitoleic acid cis-Hexadec-9-enoic acid 16:1 (n-7) Oleic acid cis-Octadec-9-enoic acid 18:1 (n-9) Elaidic acid (trans-oleic acid) trans-Octadec-9-enoic acid 18:1 (n-9) 11-Eicosenoic acid (gondoic acid) cis-Eicos-11-enoic acid 20:1 (n-9)
- 13. Common Name Lipid Numbers Chemical Name List of some Omega-3 Poly-Unsaturated Fatty Acids Alpha-linolenic acid 18:3 (n-3) all-cis-9,12,15-octadecatrienoic acid Eicosapentaenoic acid 20:5 (n-3) all-cis-5,8,11,14,17-eicosapentaenoic acid Docosahexaenoic acid 22:6 (n-3) all-cis-4,7,10,13,16,19-docosahexaenoic acid List of some Omega-6 Poly-Unsaturated Fatty Acids Linoleic acid 18:2 (n-6) all-cis-9,12-octadecadienoic acid Gamma-linolenic acid 18:3 (n-6) all-cis-6,9,12-octadecatrienoic acid α-linolenic acid 𝛄-linolenic acid
- 14. • Shorter fatty acids usually have lower melting points than longer ones (stearic acid [18C] = 70ºC, palmitic acid [16C] = 63ºC) FATTY ACIDS – Melting Property • The cis-double bonds in unsaturated fatty acids put an inflexible “kink” in the carbon chain, preventing the molecules from packing together as tightly as saturated fatty acids do.
- 15. • Animal fats and vegetable oils are esters composed of three molecules of a fatty acid connected to a glycerol molecule, producing a structure called a triglyceride or a triacylglycerol STRUCTURE OF FATS AND OILS TRIGLYCERIDES
- 16. • The fatty acids in a triglyceride molecule are usually not all the same; natural triglycerides are often mixtures of many different triglyceride molecules TRIGLYCERIDES
- 17. • Fats are triglycerides that are solids at room temp. – usually derived from animals & mostly saturated fatty acids • Oils are triglycerides that are liquids at room temp. – usually derived from plants or fish & mostly unsaturated fatty acids TRIGLYCERIDES
- 19. TRIGLYCERIDES - Saponification carboxylate salts of the fatty acids
- 21. • Waxes are simple lipids contain a fatty acid joined to a long-chain (12-32 carbons) alcohol WAXES
- 22. • Waxes are insoluble in water, and not as easily hydrolysed as fats and oils. They often occur in nature as protective coatings on feathers, fur, skin, leaves, and fruits. • Sebum, secreted by the sebaceous glands of the skin, contains waxes that help to keep skin soft and prevent dehydration. • Waxes are used commercially to make cosmetics, candles, ointments, and protective polishes. WAXES
- 23. • Phosphoglycerides are complex lipids that are major components of cell membranes. Phosphoglycerides and related compounds are also called phospholipids. PHOSPHOGLYCERIDES
- 24. • The most abundant phosphoglycerides contain the alcohols choline, ethanolamine, or serine attached to the phosphate group. PHOSPHOGLYCERIDES - Aminoalcohols
- 25. • Phosphoglycerides that contains the aminoalcohol ‘choline’ are called lecithins. • The fatty acids at the first and second positions are variable, so there are a number of different possible lecithins. • They act as an emulsifying agent PHOSPHOGLYCERIDES – (Aminoalcohol) – Lecithin
- 26. • Phosphoglycerides that contains the aminoalcohol ‘ethanolamine or serine’ are called lecithins. • Cephalins are found in most cell membranes, and are particularly abundant in brain tissue. They are also found in blood platelets, and play a role in blood- clotting. PHOSPHOGLYCERIDES – (Aminoalcohol) – Cephalin
- 27. • Sphingolipids are complex lipids that contain sphingosine instead of glycerol. SPHINGOLIPIDS
- 28. • One important type of sphingolipds are the sphingomyelins. SPHINGOLIPIDS - Spingomyelin SPINGOMYELIN • Sphingomyelins are found brain and nerve tissue, and in the myelin sheath that protects nerves
- 29. • Sphingomyelins - a bilayer that wraps around nerve cell axons SPHINGOLIPIDS - Spingomyelin
- 30. • Glycolipids are sphingolipids that contain carbohydrates (usually monosaccharides). They are also referred to as cerebrosides because of their abundance in brain tissue SPHINGOLIPIDS - Glycolipids Cerebroside
- 31. • Most cell membranes contain about 60% lipids (Amphipathic Lipids) and 40% proteins. • The fluid- mosaic model : Cell membrane - Lipid bilayer BIOLOGICAL MEMBRANES - Membrane Structure membrane re- forming @ damage
- 32. The Fluid Mosaic Model
- 33. STERIODS • Steroids are classified as lipids because they are soluble in nonpolar solvents, but they are non-saponifiable because the components are not held together by ester linkages • The basic steroid structure contains four fused rings • There are three important types of steroids: 1) Cholesterol 2) Steroid hormones 3) Bile salts
- 34. STERIODS - Cholesterol • Cholesterol is the most abundant steroid in the body. • it is manufactured in the liver. • It is an essential component of cell membranes, and is a precursor for other steroids, such as the bile salts, sex hormones, vitamin D, and the adrenocorticoid hormones. • There is apparently a correlation between high levels of cholesterol in the blood and atherosclerosis.
- 35. STERIODS – Steroid hormones • Hormones, molecules that regulate the function of organs and tissues, come in a variety of forms. • Some, such as sex hormones and adrenocorticoid hormones, are steroids • Sex hormones produced in the testes and ovaries regulate the production of sperm and eggs and aid in the development of secondary sex characteristics Eg.: testosterone, estradiol, progesterone • Adrenocorticoid hormones are produced in the adrenal glands (located on the top of the kidney). Eg.: Glucocorticoids - Cortisol and its derivatives, cortisone and prednisolone
- 38. STERIODS - Bile Salts • Bile is a yellowish brown or green fluid produced in the liver and stored in the gall bladder.
- 39. PROSTAGLANDINS • Prostaglandins are cyclic compounds synthesized from arachidonic acid. Like hormones, they are involved in a host of body processes, including reproduction, blood clotting, inflammation, and fever. • Prostaglandins have a wide range of biological effects: – causing pain – causing inflammation – causing fever – affecting blood pressure – inducing labor (PGE2)