Note: Part of this answer related to globular protein appears in the
comments section below.
Both use the hydrophobic effect. Lipids have one end that avoids
water and the other that doesn't. When a bunch of lipids get
together, they line up with their water-avoiding ends together.
Imagine a large field of corn, with rows and corn stalks. Now mirror
that vertically, so that you have the identical scene repeated upside
down; half the corn is growing up and half the corn is growing down.
That's how lipids arrange themselves into bilayers to form membranes.
Children's Hospital of Oakland explains, "Often a happy solution for
phospholipids is a double layer with the hydrocarbon chains
sequestered away from the water in the interior of the bilayer , while
the polar phospholipid head groups maintain contact with the aqueous
phase." They describe the shape of proteins by saying, "Similarly,
protein amino acid regions with hydrophobic side chains sequester away
from water while polar amino acid side chains are exposed to the
They also have a good diagram:
Another explanation says, "Each represents a phospholipid. The
circle, or head, is the negatively charged phosphate group and the two
tails are the two highly hydrophobic fatty acid chains of the
phospholipid. Due to their thermodynamic properties they spontaneously
form a double layer in an aqueous (watery) environment." Also has
For a more technical explanation, see "General Principles of Membrane
Protein Folding and Stability" from the Steven White Laboratory at UC
Irvine. The page also provides links more details on lipid layer
So to put it simply, globular proteins and lipid bilayers both depend
on the hydrophobic properties of their molecular components. A
globular protein attains a 3D shape that is driven by the hydrophobic
properties of areas along its length, as they try to "hide" from the
aqueous surroundings. Lipids line up in two mirror image planes
because it is the most efficient way to keep all the hydrophobic ends
away from the aqueous surroundings.
My answer here along with my comment in the comments section below
provides the complete answer. I hope my visual examples have helped
and not offended in their simplicity.