Lipids
-include fats, phospholipids, and steroids
-heavily hydrocarbon in nature and
insoluble in water
-function as a compact energy storage
(twice the energy per gram than
either
carbohydrates or proteins), protection, and insulation
FATS
-made from glycerol and fatty acids (most
have 14-16 carbons) in ester
linkages
-saturated fats contain fatty acids with maximum
number of hydrogens,
are usually solid
at room temperature, and are associated with animal
fats
-unsaturated fats have one or more fatty
acids with one or more double
bonds, are usually
liquid at room temperature, and are associated with
plant fats (oils)
PHOSPHOLIPIDS
-found in all cell membranes
-made from glycerol, two fatty acids, and a
phosphate with an additional
small chemical
(often choline)
-hydrocarbon "tails" are
hydrophobic, phosphate "head" is hydrophilic
STEROIDS
-characterized by four fused carbon rings
Cholesterol is part of animal membranes and
is a building block of many
other steroids,
such as sex hormones (testosterone and estrogen) and
bile acids
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/SexHormones.html
PROTEINS
-make up to 50% of dry weight of cells
-serve many functions
a) structural
support
b) amino acid
storage
c) transport
d) signalling
e) reception of
stimuli
f) movement
g) immunity
h) biological
catalysts (enzymes)
- synthesized on ribosomes
from 20 different amino acids
- each amino acid contains
a central carbon, an amino and a carboxyl group
and a variable
side chain (R-group)
- amino acids join together with peptide bonds in an
invariable polarity:
amino
(N-terminus) to carboxyl (C-terminus)
- the backbone can
be seen as N-C-C-N-C-C...
- the polymer is
called a polypeptide and is not an active protein until
several stages of structural folding occur
and modifications are made
- the conformation of the protein is its 3-dimensional shape