The Cell Membrane FOS 3 Infectious Disease Unit
Composition of Cell Membrane
- Cell Membranes are NOT all identical, but have FOUR common parts:
- Network of supporting fibers
Lipid Foundation- Phospholipid Bilayer
- 2 Fatty Acid tails (nonpolar/
- Phosphate Head (polar/hydrophilic)
Lipid Foundation- Phospholipids
- Fatty Acid side is NONPOLAR
- Creates barrier to water soluble molecules
- Lipid bilayer is fluid, yet stable.
Fluid Mosaic Model
History of the Fluid Mosaic Model
- If you want more information of this go to:http://www1.umn.edu/ships/9-2/membrane.htm
Controls the fluidity of the Cell Membrane
- Length of tails and kinks in tails
Cholesterol in Cell Membrane
- The phospholipid bilayer also contains cholesterol molecules. This gives the layer greater strength, more flexibility, less fluid and less permeable to ions and monosaccharides.
How do things get through if there is a barrier?
- Through “kinks” in the fatty acid tails
- Closely aligned tails have C-C (single bonds)
- C=C (double/triple bonds) cause “kinks”
Protein Functions in the Membrane
- Cytoskeleton attachment and support
Transmembrane Proteins extend across lipid bilayer
- These proteins can have both a polar and a nonpolar region.
Proteins act as Cell Identification Markers
- Glycolipids and glycoproteins
- This is particularly important in the immune system
Major Histocompatibility Complex
- Unique to every individual
- Consists of proteins that attach to exterior cells and antigens
- Allows T-Cells in the immune system to recognize and attack foreign cells
- Glycolipids also differentiate between tissues of same individual
- A, B, AB and O blood group markers.
Cell Surface Receptors
- They do not extend through the membrane
- They bond and drag molecules through the lipid bilayer and release them on the opposite side.
Proteins used to attach Cytoskeleton
- Receptor proteins help to attach the cytoskeleton inside the cell.
Membrane Protein Functions Receptor
Membrane Protein Functions