http://www.expasy.ch/cgi-bin/show_image?E9
Double bond conjugations are found in the side chain.They can be cleaved at certain carbon positions.Are they vinyl group bonds ??
http://www.expasy.ch/cgi-bin/show_image?D9&right
Carbon double bonds are less stable than single bonds.
They love to absorb energy inorder to break those bonds and form a single bond with a univalent radical group.
They want to be saturated to form single bonds. ie: hydrogenation,hydroxylation,oxidation...chlorination.....

IRRADIATION.....high energy forms from the sun.

Note: All chemistries of humans and animals want to resolve to X-COOH's ( carboxcylic acid ie: amino acids) ,carbon saturation with univalent radical OH's ( hydroxyls ) or ketones.

If you review Gerhard Michal's Biochemical Pathways ( Boehringer-Mannheim Biochemical Pathways )at http://www.expasy.ch/ and search at http://us.expasy.org/cgi-bin/search-biochem-index

You will find that there are not too many substances found in a human that have double carbon bonds.

Humans going into space will have problems with the chemistries of the eye . Other substances that can be transformed by higher energy irradition of the electro-magnetic spectrum will be a problem too.

Now the brain teaser is getting more interesting. Whales survived a climatic change that allowed more Ultra-Violet to reach the surface of the earth.Whales have large bones.Imagine the Calcium metabolism that takes place in these creatures.

Were Dinasaurs MAMMALS ??

Are the bails still up ??
Bring on the next innings.
Striker is ready for Bodyline.
regards,