The Cell MembraneThe Cell Membrane

FOS 3Infectious Disease Unit

FOS 3Infectious Disease Unit

Composition of Cell Membrane

Composition of Cell Membrane

Cell Membranes are NOT all identical, but have FOUR common parts: Lipid Bilayer Transmembrane Protein

Network of supporting fibers

Glycoproteins

Cell Membranes are NOT all identical, but have FOUR common parts: Lipid Bilayer Transmembrane Protein

Network of supporting fibers

Glycoproteins

Lipid Foundation- Phospholipid BilayerLipid Foundation-

Phospholipid BilayerConsist of a:

Glycerol backbone

2 Fatty Acid tails (nonpolar/

hydrophobic)Phosphate Head (polar/hydrophilic)

Consist of a:Glycerol backbone

2 Fatty Acid tails (nonpolar/

hydrophobic)Phosphate Head (polar/hydrophilic)

Lipid Foundation- Phospholipids

Lipid Foundation- Phospholipids

Fatty Acid side is NONPOLARNonsoluble in water

Phosphate side is POLARSoluble in water

Fatty Acid side is NONPOLARNonsoluble in water

Phosphate side is POLARSoluble in water

Lipid BilayerLipid Bilayer

Creates barrier to water soluble molecules

Lipid bilayer is fluid, yet stable.

Creates barrier to water soluble molecules

Lipid bilayer is fluid, yet stable.

Fluid Mosaic ModelFluid Mosaic Model

History of the 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

If you want more information of this go

to:http://www1.umn.edu/ships/9-2/membrane.htm

Controls the fluidity of the Cell MembraneControls the fluidity of the Cell Membrane

TemperatureLength of tails and kinks in tails

Cholesterol

TemperatureLength of tails and kinks in tails

Cholesterol

Cholesterol in Cell Membrane

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.

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?

How do things get through if there is a

barrier?Simple diffusion.Through “kinks” in the fatty acid tailsClosely aligned tails have C-C (single bonds)

C=C (double/triple bonds) cause “kinks”

Simple diffusion.Through “kinks” in the fatty acid tailsClosely aligned tails have C-C (single bonds)

C=C (double/triple bonds) cause “kinks”

Protein Functions in the Membrane

Protein Functions in the Membrane

Transmembrane ID MarkersReceptorsChannelsCarrierCytoskeleton attachment and support

Transmembrane ID MarkersReceptorsChannelsCarrierCytoskeleton attachment and support

Transmembrane Proteins extend across lipid

bilayer

Transmembrane Proteins extend across lipid

bilayerThese proteins can have both a polar and a nonpolar region.

These proteins can have both a polar and a nonpolar region.

Proteins act as Cell Identification MarkersProteins act as Cell

Identification MarkersGlycolipids and glycoproteinsCell ID MarkersThis is particularly important in the immune system

Glycolipids and glycoproteinsCell ID MarkersThis is particularly important in the immune system

Major Histocompatibility

Complex

Major Histocompatibility

ComplexUnique to every individualExcept identical twins

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 individualA, B, AB and O blood group markers.

Unique to every individualExcept identical twins

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 individualA, B, AB and O blood group markers.

Cell Surface ReceptorsCell Surface Receptors

Channel ProteinsChannel Proteins

Carrier ProteinsCarrier Proteins

They do not extend through the membrane

They bond and drag molecules through the lipid bilayer and release them on the opposite side.

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 CytoskeletonProteins used to

attach CytoskeletonReceptor proteins help to attach the cytoskeleton inside the cell.

Receptor proteins help to attach the cytoskeleton inside the cell.

Membrane Protein Functions

Membrane Protein Functions

Receptor

Membrane Protein Functions

Membrane Protein Functions