Are a diverse group of
molecules that contains
regions composed almost
entirely of hydrogen and
carbon, with nonpolar
carbon-carbon and
carbon-hydrogen bonds.
Most lipids are
hydrophobic and
water insoluble.
Fatty acid
Are long chains of
carbon and hydrogen
with a carboxylic acid
group at one end.
Oils, fats and waxes, esch
contains one or more
fatty acids subunits.
Oils and fats
Are formed by dehydration
synthesis linking three fatty
acid subunits to one molecule
of glycerol. This structure is
named triglycerides.
Are used primarily as
energy-storage molecules, they
contain more than twice as
many calories per gram as do
carbohydrates and proteins.
The difference
between a fat and
an oil, lies in the
structure of their
fatty acids
subunits.
In fats, the carbons of fatty
acids are joined by single
bonds. These described as
saturated, because they
contain as many hydrogen
atoms as possible.
If there are double
bonds betwen some
of the carbons, and
consequently fewer
hydrogens, the fatty
acid is unsaturated.
Waxes
Are chemically
similar to fats. Are
highly saturated
and solid at normal
temperatures.
Phospholipids
The plasma membrane
that surrounds each cell
cointains severak types
of phospholipids.
Has two dissimilar ends. At one end,
are two nonpolar fatty acid
"tails"(insoluble in water). And the
other, is a polar phosphate-nitrogen
"head" (soluble in water.