Chapter 25
Lipids
25-01

Labeled
Title
 Simple and Complex Lipids
Caption
 Figure 25-1 Complex lipids contain ester functional groups that can be hydrolyzed to acids and alcohols. Simple lipids are not easily hydrolyzed.
Notes
 Lipids are substances that can be extracted from cells and tissues by non-polar organic solvents.
Keywords
 fat, steroid, wax, terpene, lipid
25-01-03T01

Labeled
Title
 Structures and Melting Points of Some Common Fatty Acids
Caption
 Saturated fatty acids have melting points that increase gradually with their molecular weight.
Notes
 The presence of cis double bonds lowers the melting point.
Keywords
 saturated fatty acid, melting point
25-02

Labeled
Title
 Cis Double Bonds
Caption
 Figure 25-2 The cis double bond in oleic acid lowers the melting point by 66oC.
Notes
 The lower metling point result from the unsaturated acid's "kink" at the position of the double bond. Kinked molecules cannot pack as tightly together in a solid as the uniform zigzag chains of a saturated acid.
Keywords
 oleic acid, saturated fatty acid
25-03

Labeled
Title
 Triglycerides
Caption
 Figure 25-3 Unsaturated triglycerides have lower melting points because their unsaturated fatty acids do not pack as well in a solid lattice.
Notes
 Triolein has the same number of carbon atoms in tristearin, but triolein has three cis double bonds, whose kinked conformations prevent optimum packing of the solid.
Keywords
 triglycerides, unsaturated fatty acid, tristearin, triolein
25-04

Labeled
Title
 Electrostatic Potential Map of Soap
Caption
 Figure 25-4 The electrostatic potential map of a soap molecule shows high electron density in the negatively charged head and medium electron density (gree) in the hydrocarbon tail.
Notes
 In water, soap forms a cluody solution of micelles, with the hydrophilic heads in contact with water and the hydrophobic tails clustered in the interior. The Na+ ions (not shown) are dissolved in the water surrounding the micelle.
Keywords
 electrostatic potential map, hydrocarbon tail, micelles, hydrophilic heads
25-05

Labeled
Title
 Emulsification of Grease
Caption
 Figure 25-5 In a soapy solution, grease is emulsified by forming micelles coated by the hydrophylic carboxylate groups of the soap.
Notes
 The resulting mixture of two insoluble phases (grease and water), with one phase dispersed throughout the other in small droplets, is called an emulsion.
Keywords
 emulsion, micelles
25-06

Labeled
Title
 Synthetic Detergents
Caption
 Figure 25-6 Synthetic detergents may have anionic, cationic, or nonionic hydrophylic functional groups. Of these detergents, only Gardol¨ is a carboxylate salt and forms a precipitate in hard water.
Notes
 Synthetic detergents avoid precipitation by using other functional groups in place of carboxylic acid salts.
Keywords
 hydrophylic, hydrophobic, precipitation
25-07

Labeled
Title
 Phosphoglycerides
Caption
 Phosphoglycerides can aggregate into a bilayer membrane with their polar heads exposed to the aqueous solution and the hydrocarbon tails protected within.
Notes
 This lipid bilayer is an important part of the cell membrane, it restricts the flow of water and dissolved substances.
Keywords
 phosphoglycerides, aggregates, lipid bilayer
25-08

Labeled
Title
 Cis-Trans Decalins
Caption
 Figure 25-8 Cis-trans isomers of decalin.
Notes
 In trans-decalin, the two bonds to the second ring are trans to one another, and the hydrogens on the junction are also trans. In cis-decalin, the bonds to the second ring are cis, and the junction hydrogens are also cis.
Keywords
 decalin
25-09

Labeled
Title
 Cis and Trans Steroids
Caption
 Figure 25-9 Common steroids may have either a cis or a trans A-B ring junction. The other junctions are normally trans.
Notes
 Most steroids have the all-trans structure, which results in a stiff, nearly flat molecule with the two axial methyl groups perpendicular to the plane.
Keywords
 steroids
25-10

Labeled
Title
 Cortisol
Caption
 Figure 25-10 Cortisol is the major natural hormone of the adrenal cortex. Fluocinolone acetonide is more potent for treating akin inflammation, and beclomethasone is more potent for treating asthma.
Notes
Keywords
 cortisol, fluocinolone acetonide, beclomethasone
25-11

Labeled
Title
 Biosynthesis of Prostaglandins
Caption
 Figure 25-11 Biosynthesis of prostaglandins begin with an enzyme-catalyzed oxidative cyclization of arachidonic acid.
Notes
Keywords
 arachidonic acid, prostaglandin
25-12

Labeled
Title
Caption
 Figure 25-12 Cholesterol is a triterpenoid that has lost three (blue) carbon atoms from the original six isoprene units of squalene.
Notes
 Another carbon atom has migrated (red arrow) to form the axial methyl group between rings C and D.
Keywords
 cholesterol, triterpenoid, isoprene
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