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Chapter 13 Lipids

Chapter 13 Lipids. Tiara Bartol and Brant Houghton. 13.1 What are lipids?. Family of substances that are insoluble in water but soluble in nonpolar solvents and solvents of low polarity Defined in terms of properties. Classification of Function. 3 roles Storage energy within fat cells

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Chapter 13 Lipids

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  1. Chapter 13 Lipids Tiara Bartol and Brant Houghton

  2. 13.1 What are lipids? • Family of substances that are insoluble in water but soluble in nonpolar solvents and solvents of low polarity • Defined in terms of properties

  3. Classification of Function • 3 roles • Storage energy within fat cells • Part of membranes that separate compartments of aqueous solutions • Serve as chemical messengers • Storage • Important in animals • Use fats for storage • Glycogen • Greater amount of energy • 9 Kcal/g

  4. Membrane Component • Lipids lack water solubility • The body needs insoluble compounds for membranes that separate aqueous solutions • Derives from smaller polar groups than alkane like portions • Nonpolar provide hydrophobic part

  5. Messengers • Primary messenger delivers signals from one part of body to another • Steroid hormones • Secondary messenger meditates hormonal response • prostaglandins and thromboxanes

  6. Classification by Structure • 4 groups • Simple lipids • Fats and waxes • Complex lipids • Steroids • Prostaglandins, thromboxanes, and leukotrienes

  7. 13.2 What are structures of Triglycerides? • Triglyceride • Animal fats and plant oils • Triesters of glycerol and long chain carboxylic acids called fatty acids

  8. Even number of acids • Aka triacylglycerols • 3 groups of glycerol are esterified • Complex mixtures • Most cases 2 or 3 different fatty acids are present • Hydrophobic character is caused by long chain • Esters are buried in nonpolar environment which makes them insoluble

  9. Fatty acids • Practically all unbranched carboxylic acids • 10 to 20 carbosn • Even # of carbons • Cis isomer predominates • Mono and diglycerides • Not infrequent • Latter two sides • 1 or 2 OH groups are esterified

  10. 13.3 What are properties of Triglycerides? • Fats • A mixture of triglycerides containing a high proportion of long chain, saturated fatty acids • Oils • A mixture of triglycerides containing a high proportion of long chain, unsaturated fatty acids or short chain, saturated fatty acids

  11. Physical State • Fats are generally solids at room temperature • Fats from plants and fish are liquids • Liquid fats are oils • Solid fats are mainly saturated fatty acids • Vegetable oil has high amounts of unsaturated fatty acids • Essential fatty acids • The body needs but can’t synthesize

  12. Most oils contain large amounts of unsaturated fatty acids • Coconut oil has a small amount • Polyunsaturated fatty acids have more than one double bond • Pure fats and oils are colorless, odorless, and tasteless • To gain taste substances must be added

  13. Hydrogenation • Easy to convert unsaturated liquids and oils to solids • Don’t hydrogenate all double bonds • It will become too solid • This is the source of trans fatty acids

  14. Saponification • Base promoted hydrolysis of fats and oils • Produce glycerol and a mixture of fatty acids called soap • It is the oldest known chemical reaction

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