Cell structure
5
1
RETPaHC
CC MMVV AAPPMM
AAJJCC
Receptor
Transmembrane protein
pore complex
of proteins
Carbohydrate
residues
External
(extracellular)
surface
MM
MM
CCyy
LLPPMM
Internal
(intracellular)
surface
NN Lipid bilayer
appearance
in electron
microscope
Intrinsic
membrane
protein Extrinsic Transmembrane
protein
protein Transport Non-polar tail
or diffusion of phospholipid
channel Cytoskeletal
Polar end of
element
EENN phospholipid
Fig . 1 .3 The molecular organization of the plasma membrane, according
to the fluid mosaic model of membrane structure . Intrinsic or integral
membrane proteins include diffusion or transport channel complexes,
receptor proteins and adhesion molecules . These may span the thickness
of the membrane (transmembrane proteins) and can have both
extracellular and cytoplasmic domains . Transmembrane proteins have
hydrophobic zones, which cross the phospholipid bilayer and allow the
Fig . 1 .2 The structural organization and some principal organelles of a