CHEM 30 B    Dr. R. Rinehart
Chapter 18  LIPIDS

  A highly heterogeneous group of substances defined on the basis of solubility, not  composition. To wit, lipids are insoluble in water, but soluble in one or more nonpolar solvents such as: chloroform, diethyl ether, methylene chloride, toluene, hexane, isooctane, acetone, etc. etc. etc.  They are critical for life as we know it, as sources of energy and as components of cell membranes. 

I. CLASSES of lipids: based on chemical properties and components  
A. NONSAPONIFIABLE [not broken down by NaOH(aq) + heat]
  Fat-soluble vitamins:  A, D, E, K      
. SAPONIFIABLE: contain groups [usually ester] attacked by NaOH
1. Simple
. Waxes: esters of long-chain fatty acids with long-chain fatty alcohols
TRIGLYCERIDES: triple esters of glycerol with fatty acids   
                        2. Complex


. FATTY ACIDS   Learn these!     See table of lipids
A. Saturated
B. Unsaturated

C. Soaps and surfactant activity 

III. TRIGLYCERIDES: fats and oils
A. Structures
B. Physical Properties
1. Solubility; insoluble in H2O
2. Melting point: lowered by presence of cis C=C

            C. Chemical properties: reactions

                        1. Hydrolysis
         2. Saponification
         3. Hydrogenation
            D. Biological functions
                        1. Energy production: 9 kcal/g [~4000 Cal/lb]
                        2. Energy storage
                        3. Insulation: blubber           

A. Components: glycerol, 2 fatty acids, phosphate, N-containing alcohol
B. Classes

                        1. phosphatidyl choline [lecithins]
2. Phosphatidyl serine or ethanolamine [cephalins]
C. Importance

1. Emulsifiers: why mayonnaise is made from oil and egg yolks

A nice illustrated discussion of the various classes of lipids and their role in cell membrane formation  
by Joyce J. Diwan at Rensselaer Polytechnic Institute is viewable at 
Some of the material requires Chime
John W. Kimball's page on membranes
The membrane page from U Minnesota WWW Cell Biology Course and Online Book by Mark Dalton
another one bit the dust!!!
GIF pictures of the crystal, gel, and fluid states of cell membranes by Eric Martz of U Mass are at
and an interactive Chime display of membrane assembly by Eric Mertz is at
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
a tutorial on membranes with animations at
The following pages are authored by William McClure and Joseph Grotzinger of Carnegie-Mellon University:
an interactive Chime depiction of lipids
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
Chime structures of steroids
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
an interactive Chime depiction of a lipid micelle
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
interactive Chime depiction of lipid bilayer membranes
by William McClure, Carnegie Mellon University
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
to compare the crystal, gel, and fluid states of a membrane [Netscape only]
The World of Membrane Lipids by Lesa Beamer at U Missouri
Membrane page by Gordon Rule at Carnegie-Mellon University  
a basic introduction to membranes from the Biology Hypertextbook at M.I.T.
membranes and membrane transport by Tom Terry at UConn
and the membrane page from the University of Texas Medical Branch at Galveston
micelle.htm     membr1.htm     membrgel.htm     memfluid.htm     membrxtl.htm
Lipids by Warren Gallagher at the University of Wisconsin, Eau Claire
Lipid Biochemistry by Dr. Don DeWitt at Bergen County Academies, NJ
A total winner!!!!


A. Sphingosine and dihydrosphingosine
B. Ceramide  =  N-acyl sphingosine
C. Sphingomyelin = ceramidyl phosphocholine
D. Cerebrosides = ceramidyl galactose or glucose
E. Gangliosides = ceramidyl group attached to more complex carbohydrates
F.  Genetic disorders of sphingolipid metabolism  

VI. STEROIDS; contain the steroid ring system [learn to recognize it]
1. Structure and properties
2. Functions:     waterproofing skin
                                              cell membrane component 
[smears transition between gel and fluid states - 
                                                        see pictures at U Mass and CMU sites listed above]

         precursor of other steroids listed below  
            B. BILE SALTS
; required for fat digestion and absorption
        C. STEROID hormones 
                                          cortisol: raises blood sugar, increases amino acid breakdown

                                         aldosterone: increases sodium recovery and  potassium excretion by kidneys
                        2. GONADAL [“sex steroids’]
                                a. ANDROGENS: testosterone
, androstenedione: increases muscle mass,
                                        body and facial hair, other 2o sexual
characteristics, aggressiveness
                                b. ESTROGENS:   b- estradiol:  egg development, prevents osteoporosis
                                c. PROGESTINS:   progesterone: prepares uterine lining for implantation  

VII. EICOSANOIDS: 20-carbon compounds derived from arachidonic acid or EPA
            A.  PROSTAGLANDINS: produced from arachidonic acid and “EPA” 
do all sorts of things in all sorts of places; aspirin blocks synthesis
            B.  PROSTACYCLINS and THROMBOXANES: involved in control of platelet aggregation
            C.  LEUKOTRIENES:  involved in inflammatory response

Additional resources:
 "Meet the Fats" by Paul Reisberg at Wellesley has Chime structures of common lipids and Olestra and other stuff.
[assuming you have Chime installed -- only the Netscape version seems to work at all here]
Olestra pages by Dan Berger at Bluffton College; requires Chime
a brief PowerPoint intro to lipids by James Hardy at U Akron 
a topic outline from a similar course by Clarke Earley at Kent State University, Starke Campus
an illustrated outline pretty similar to mine, but prettier to look at -- doesn't have my fabulous table of lipids, though!!!
definitions of different classes of lipids
How and why soap was invented by Kevin Dunn at Hampden-Sydney College  
check out the A to Z encyclopedia... when you have a lot of time on your hands 
"Long-Suffering Lipids Gain Respect" by Jennifer Fisher Wilson,
in the March 10, 2003 issue of The Scientist [free registration required, provide your email address]
takes %^&*#$@ forever to display....


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© Ronald W. Rinehart, 2003-7