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LIPIDS

ECDA, MD August 2009. LIPIDS. LIPIDS. Lipids are important structural elements of biological cell membranes. And like carbohydrates, they are important sources of energy.

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LIPIDS

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  1. ECDA, MD August 2009 LIPIDS

  2. LIPIDS Lipids are important structural elements of biological cell membranes. And like carbohydrates, they are important sources of energy. Lipid molecules may be classified as fatty acids, cholesterols, glycerides, phospholipids, phosphoglycerides, and glycolipids.

  3. LIPIDS

  4. LIPID BILAYER

  5. PHOSPHOLIPIDS

  6. FATTY ACIDS

  7. FATTY ACIDS • Fatty Acids, as components of phospholipids, are important structural elements of cell membranes. • They can be converted to great amount of energy once hydrolyzed or metabolized.

  8. FATTY ACIDS • Fatty acids are mainly derived from the diet. • 30%-40% of the calories ingested each day in the average human diet are provided by the fatty acid components or triacylglycerols and phospholipids. • Because of the relationship between a diet high in fat and heart disease, Heart Associations throughout the world recommend that no more than 30% of the calories in our diet be derived from fatty acids

  9. FATTY ACIDS • Dietary lipids are degraded by lipases and phospholipases, which are enzymes secreted into the intestinal lumen from the pancreas. • If the diet does not provide sufficient lipid to satisfy immediate needs, the fatty acids stored in the adipose tissues in the form of triacylglycerols may be required.

  10. FATTY ACIDS • Fatty acids may be classified as either saturated or unsaturated • Saturated fatty acids are long carbon chains with no double bonds linked to carbon atom • Unsaturated fatty acids, on the other hand, has 1 or more double bonds linked to carbon atoms

  11. FATTY ACIDS Saturated Fatty Acids

  12. FATTY ACIDS Unsaturated Fatty Acids

  13. FATTY ACIDS • Linoleic, linolenic, and arachidonic acids are essential fatty acids and are denoted by another short hand notation based on the omega system • Omega system denotes the methyl carbon (terminal sp3-hybridized carbon) as the omega (ω) carbon. • Linoleic acid as 18:2ω6 • Linolenic acid as 18:3ω3 • Arachidonic acid as 20:4ω6

  14. FATTY ACIDS • Unsaturated fatty acids are very reactive substances • These molecules are easily hydrogenated, halogenated, and oxidized because of double bonds • Polyunsaturated fatty acids are also susceptible to peroxidation and will react readily with molecular oxygen • This results in the development of undesirable flavors and color or production of food with low nutritive value, or may lead to formation of toxic products.

  15. FATTY ACIDS • Unsaturated fats do not raise blood cholesterol. Foods with unsaturated fats include olives, avocados, fatty fish, like salmon, and most nuts. Olive, canola, sunflower, soybean, corn, and safflower oils are high in unsaturated fats. • Even though unsaturated fats don't raise blood cholesterol, all types of fat are high in calories and should be eaten in limited amounts.

  16. FATTY ACIDS

  17. GLYCEROLS

  18. GLYCEROLS • Glycerol, also commonly called glycerin or glycerine, is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. • Glycerol is a precursor for synthesis of triacylglycerols and of phospholipids in the liver and adipose tissues. When the body uses stored fat as a source of energy, glycerol and fatty acids are released into the bloodstream.

  19. GLYCEROLS • Glycerol is a sugar alcohol also, and has three hydrophilic alcoholic hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature.

  20. GLYCERIDES

  21. GLYCERIDES • Glycerides, more correctly known as acylglycerols, are esters formed from glycerol and fatty acids • Glycerol has three hydroxyl functional groups, which can be esterified with one, two, or three fatty acids to form monoglycerides, diglycerides, and triglycerides, respectively. • Two types: • 1. partial glycerides • A. Monoglycerides • B. Diacylglycerols • 2. triglycerides

  22. GLYCERIDES monoglyceride diglyceride

  23. GLYCERIDES triglyceride

  24. GLYCERIDES • Glycerides are important nutritionally, being the storage form of fats in cells • The most abundant fatty acid in natural glycerides are palmitic, stearic, oleic, and linoleic acids.

  25. GLYCERIDES • The ester groups of this class of lipids may be cleaved by alkali, acid or enzymes. • Alkali hydrolysis in vitro is called saponification producing soaps in the process. The reaction is shown RCOOH + NaOH RCOO- Na+ + ROH

  26. SAFONIFICATION

  27. GLYCERIDES • Enzymatic hydrolysis can be effected by lipases or phopholipases which breaks ester bonds to release the free fatty acid. This process is an important requisite for the utilization or mobilization of stored fats. • Nomenclature: • All glycerides are named as derivatives of glycerol. • The carbons of glycerol are numbered 1 to 3 from top to bottom. • The fatty acyl substituent are mentioned in 1 to 3 order.

  28. HYDROLYSIS

  29. QUESTIONS

  30. GLYCERYL ETHERS • Glyceryl ethers are rare lipids and are mostly found in neoplasms or cancer cells in the body • The main feature of the glyceryl ethers is the presence of an ether linkage between fatty acid and glycerol

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