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Lipids - PowerPoint PPT Presentation


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Lipids. Store Energy in a Fat Cell Part of membranes Serve as chemical messengers. Energy Storage. Humans store Energy in the form of fats Some Energy storage is in the form of the carbohydrate glycogen – fast energy Fats produce 50% more energy per gram than carbohydrates

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Lipids


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    1. Lipids • Store Energy in a Fat Cell • Part of membranes • Serve as chemical messengers

    2. Energy Storage • Humans store Energy in the form of fats • Some Energy storage is in the form of the carbohydrate glycogen – fast energy • Fats produce 50% more energy per gram than carbohydrates • 9 kcal/gram compared to 4 kcal/gram

    3. Membrane Components • Because lipids are insoluble in water, they work well as membranes to separate compartments in the body • The structure of lipids makes them water repellent or hydrophobic

    4. Messengers • Primary messengers like steroids • Secondary messengers like prostaglandins or thromboxanes

    5. Classification of Lipids • Classified into four groups 1) Fats and waxes 2) Complex Lipids 3) Steroids 4) Prostaglandins

    6. Structure of Fats • Fats are esters • Alcohol part is always glycerol • Acid part varies but is a “Fatty Acid” also called “glycerin” a typical “fatty acid”

    7. Structure of Fats • Fatty Acids (FA) 1) Practically all straight chain with no branches 2) 10 to 20 C in length 3) Contain an even number of C The body builds FA from two carbon units of acetic acid (acetate ion) • Those with double bonds are usually in the cis isomer formation

    8. Structure of Fats • Fatty Acids + Glycerol = FAT (an ester) first FA glycerol second FA third FA

    9. Structure of Fats • FATS • Triglycerides (three FA esterified with glycerol) • Also called Triacylglycerides • diglycerides (two FA esterified w/ glycerol) • Monoglycerides (one FA esterified w/ glycerol) • Fats are insoluble in water • Exist as both saturated and unsaturated FA

    10. Structure of Fats • FATS • Saturated Fatty Acids • Fit together well - close, parallel alignment • Regular pattern • Unsaturated Fatty Acids • cis/trans double bonds do not allow regular packing • LOWER mp and bp lower than the Sat’d. FA

    11. Properties of Fats • Physical State - FATS • Animal fats • generally solids at RT • contain mostly saturated FA • Plant and Fish oils • generally liquids at RT • contain more unsaturated FA

    12. Properties of Fats • PURE Fats • Colorless, odorless, and tasteless • Tastes, odors, colors are caused by substances dissolved in the fats From Yahoo Images

    13. Hydrogenation • Treatment with hydrogen gas, H2 • Catalyst required • NOT difficult to convert unsaturated FA to saturated FA • Called “hardening” • Margarine contains more unsaturation than hydrogenated shortenings • Crisco, Spry, etc.

    14. Hydrogenation • Unsaturated converted to saturated:

    15. Saponification • Triglycerides are subject to hydrolysis • Can be hydrolyzed with acid or base • Base hydrolysis is called “saponification” • Result of base hydrolysis is a SOAP • SOAP • The mixture of sodium salts of Fatty Acids produced by saponification is called SOAP.

    16. Saponification • Triglycerides are subject to hydrolysis • base hydrolysis is called “saponification”

    17. Soap Making • Pre-18th century soap making… It is said of Queen Elizabeth I that she bathed once a month, "whether she needed to or not". Whether she used soap is not recorded. But soap was a commodity only available to the wealthy before modern times. • Source of “lye”… A large wooden hopper, which was large at the top and tapered down to a small bottom, was kept in the backyard near the kitchen door. The hopper was made of clapboards, which were arranged as a pyramid turned up side down. Dried grass or cornhusks were put into the bottom of the container to act as a strainer. In this the wood ashes from the hearth were stored. When the hopper was filled, many buckets of water had to be drawn from the well and poured over the ashes. Through a trough from the bottom of the hopper came the drops of strong brown lye, which was put in a large kettle over the fire to boil. As soon as the lye would float an egg, scraps of fat and grease were put in. everyone was careful not to touch the strong lye, for it would have eaten the skin off one’s fingers. (62) The grease was saved by the housewife from cooking during several months. Then it was put in the large round-bottomed iron kettle with the homemade lye. After boiling the mixture became a mass of jelly-like soap. Then it was allowed to cool, and from it were cut bars of brown soap, which were stored for household use. (63)

    18. Common Fatty Acids To Know

    19. FA Glycerol FA FA Classification of Lipids Simple and complex lipids Simple Complex

    20. FA Glycerol FA FA Classification of Lipids Simple and complex lipids Simple Complex Glycerophospholipids Glycolipids

    21. FA GLUCOSE GALACTOSE Glycerol FA Sphingosine FA FA Classification of Lipids Simple and complex lipids Simple Complex Glycolipids Glycerophospholipids

    22. FA GLUCOSE GALACTOSE Glycerol FA Sphingosine FA FA Classification of Lipids Simple and complex lipids Simple Complex Glycerophospholipids Glycolipids Sphingolipids Phosphoglycerides

    23. FA FA GLUCOSE GALACTOSE Glycerol Glycerol FA FA Sphingosine FA FA PO43- ALCOHOL Classification of Lipids Simple and complex lipids Simple Complex Glycerophospholipids Glycolipids Sphingolipids Phosphoglycerides

    24. FA FA GLUCOSE GALACTOSE Glycerol Glycerol FA FA Sphingosine Sphingosine FA FA PO43- PO43- ALCOHOL CHOLINE Classification of Lipids Simple and complex lipids Simple Complex Glycerophospholipids Glycolipids Sphingolipids Phosphoglycerides FA Sphingosine

    25. Membranes • Complex Lipids make up membranes • Hydrophilic vs. Hydrophobic

    26. Cell Membrane • Lipid layers line up with alaphatic tails inward • Unsaturation allows for liquid like character of the membrane • Intergral and peripheral proteins are a part of the structure • Cholesteral is also a component of membranes

    27. Transport Through a Membrane

    28. Membranes • Youtube • http://www.youtube.com/watch?v=GW0lqf4Fqpg • http://www.youtube.com/watch?v=ULR79TiUj80 • http://www.youtube.com/watch?v=vh5dhjXzbXc • http://www.youtube.com/watch?v=ooX9hHu5baM

    29. + Glycerophospholipids • Glycerol is the alcohol • Two acids are Fatty Acids • Third is esterified to PO43- and choline • The Fatty Acid on carbon 2 is unsaturated

    30. + Glycerophospholipids Locate: glycerol portion stearic acid choline linoleic acid phosphate • Phosphotidylcholines • Also called “lecithins” • Charged groups • Forms lipid bilayer with • Hydrophobic heads together

    31. Glycerophospholipids • Cephalins • another type of glycerophospholipids • alcohol is ethanolamine or serine instead of choline

    32. Glycerophospholipids • Phosphatidylinositols (PI) • Alcohol is inositol • Serve as signaling or Communication sites inositol

    33. Sphingolipids • Coating of nerve axons (myelin) • Alcohol portion is sphingosine (not glycerol) • A long chain fatty acid is connected to the NH2 • The End OH group is esterified by phosphorylcholine

    34. Sphingolipids Can you find the sphingosine????

    35. a glucocerebroside Glycolipids • Glycolipids contain carbohydrates • They also use sphingosine • One type is the cerebrosides • occur in the brain (7% of dry weight!) • present at nerve synapses

    36. Steroids • A third major class of lipids: • They are all based on this structure

    37. Cholesterol • most abundant steroid in the body • cell membrane component • raw material for other steroids synthesis • Exists in both free and esterified forms • Esterifies with FA • Gallstones are almost pure cholesterol • Correlation between HI serum levels and atherosclerosis • Necessary for human life • Manufactured in the liver – body keeps a set amount

    38. Lipoproteins • Transport cholesterol, and fats • Types of Lipoproteins • HDL = hi density lipoprotein (the good Kind) • 33% protein and 30% cholesterol • LDL = lo density lipoprotein (the not good kind) • 25% protein and 50 % cholesterol

    39. Steroid Hormones Cholesterol is starting material for synthesis of Progesterone: • Alcohol on C-3 converted to a ketone • Side chain on D ring modified • Precursor of sex hormones and adrenocorticoid hormones

    40. Hormones from Progesterone

    41. Steroid Hormones • Aldosterone • Product of the adrenal gland • Mineralocorticoid (regulates ion concentration) • Increased secretion enhances reabsorption of Na+ and Cl- ions in the kidney tubules

    42. Steroid Hormones • Sex Hormones - Testosterone • Promotes normal growth of male sex organs • Synthesized in testesfrom cholesterol • Secretion results in2nd sex characteristics

    43. Steroid Hormones • Sex Hormones - Estradiol • Regulates cyclic changes in the uterus • Synthesized from testosterone • Menstrual Cycle • increased estradiolat beginning of cycle • uterus thickens • Luteinizing hormonetriggers ovulation

    44. YouTube http://www.youtube.com/watch?v=9oaFmKc3ll0 http://www.youtube.com/watch?v=rBBWMRRWOrM http://www.youtube.com/watch?v=p_ewmP1L7ro

    45. Bile Salts • Bile Salts are oxidation products of Cholesterol – 3 OH’s and an Acid end • Charged salt is more soluble in solution • Bile salts help disperse dietary lipids inthe small intestine – increase digestion rate • Removes cholesterolin two ways – they are broken cholesterols and dissolve deposited cholesterol

    46. Prostaglandins • Fatty acid-like substances • Produced in prostate • small amounts producedin all tissue • Synthesized fromArachidonic Acid