Evolution What the Fossils Say and Why it Matters

160 Evolution? The Fossils Say YES!

FIGURE 6.5. Some organic chemicals have properties that enable cells to form naturally without complex organic
reactions. Lipids, the building blocks of fats and oils, have an end that repels water and an end that bonds
to water. The properties that repel or attract lipids to water naturally line them up and then combine them
to form membranes. Whenever oil mixes with water, it forms a natural membrane that encloses a droplet,
comparable to the lipid bilayer membrane that surrounds all cells.

Fatty acid

Glycerol

H 2 O

in the mosh pit in a hot nightclub. Once they are all lined up facing the same way (toward the
stage) and closely packed, it is easy to link them up side by side and make complex organic
polymers—just like the dense mass of people on the dance floor can easily link up and form
a solid carpet of arms who can pass bodies above them.