Biology Reference
In-Depth Information
FIGURE 3.9
Five
forces that stabilize the
membrane lipid bilayer in
water.
H
H
H
H
CC
C
H
H
H
H
H
O
H
H
H
H
O
O
Caged Tails
(unfavorable)
Hydrophobic Effect
(unfavorable)
H
O
H
H
O
H
+
-
+
-
+
-
Head - Head
(favorable)
Head - Water
(favorable)
van der Waals
(favorable)
by the Dutch scientist Johannes Diderik van der Waals (
Figure 3.10
) in the late 19
th
century.
For his achievements van der Waals received the 1910 Nobel Prize in Physics. In regard to
membranes, the van der Waals force is more correctly termed the van der Waals-London
force. This very weak force is neither covalent nor ionic. Instead it is the result of induced
dipoles that form instantaneously between two very close molecular surfaces. This force
increases with the length of the non-polar part of the adjacent surfaces and so is particularly
important to the densely packed acyl chains that comprise the membrane hydrophobic inte-
rior. Therefore, there are at least 5 forces stabilizing the membrane bilayer, the most important
being the Hydrophobic Effect.
