(Poly-Unsaturated Fatty Acids, that is)

Here's a link to another picture of the two structures: http://lansbury.bwh.harvard.edu/multiple_sclerosis.htm.
Scroll down a little.

They do appear both to be linear, though they might fold when they're not on paper. I think the hexagon/pentagon structure is more a linguistic seduction than actual spatial configuration, Buckminster Fuller and his geodesic dome notwithstanding.

Besides, I seem to have mis-identified DHA, too. Here it's given as DOCOSA-, not DODECA-. I think that's supposed to mean "twenty-two."

PS. I violently disclaim all responsibility for the apostrophes in the paragraph following References 1 and 2. Three times, no less! And it's (sic) from Brigham and Womens' Hospital, even - they should know better.
For shame!

PPS. Here's a link to soccerball/Buckminsterfullerene, which is C-60, it turns out.
http://ornl.gov/info/ornlreview/rev26-2/text/rndmain1.html
Alert: the movie contains two plugs for Big Industry, at the middle and the end.