Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chem 431


Fall 2008

Lecture Notes: 22 October

© R. Paselk 2008


Lipids, cont.

Conformation of saturated vs. unsaturated fatty acids (text Figure 10-2a,b)

structural diagram of general glycerophospholipid with three common R-groups diagramed, srine, ethanolamine and choline

A variety of R-groups may then be linked to the Phosphate residue (text Figure 10-9-2).


Lipid Properties: An important consideration for lipids of all sorts is their fluidity. Thus membranes must be fluid enough to allow the diffusion of proteins, transport processes etc. but not so fluid as to weaken the membranes structure. For storage want fat to be fluid enough to flow to fill out body shape at normal operating temperatures. A number of strategies are used by organisms to adjust lipid fluidity:

Lipid Bilayers

Detergents & Micelles: Polar heads of detergents and soaps (such as long chain fatty acids) tend to associate with polar solvents such as water, while non-polar "tails" are excluded by water and are forced to associate with themselves making globules known as micelles. (text Figure 11-4a)

Lipid Bilayer (text Figure 11-4b):

diagramatic drawing of an idealized lipid bilayer

Note that for a flat bilayer the lipids should be cylindrical, while for curved bilayers want "cone" and "wedge" shaped lipds.

The lipid bilayer forms the core for the lipid bilayer membrane as seen in the Fluid Mosaic Model of biological membranes.

Pathway Diagrams

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Last modified 22 October 2008