cell membrane
TRANSCRIPT
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
GlycoproteinsOn outside of cellCell Surface has a carbohydrate coat to prevent sticking.
Cell Membranes are NOT all identical, but have FOUR common parts: Lipid Bilayer Transmembrane Protein Network of supporting fibers
GlycoproteinsOn outside of cellCell Surface has a carbohydrate coat to prevent sticking.
Lipid Foundation- Phospholipid BilayerLipid Foundation-
Phospholipid BilayerConsist of a:
Glycerol backboneFatty Acid tails (nonpolar/
hydrophobic)Phosphorylated alcohol (polar/hydrophilic)
Consist of a:Glycerol backboneFatty Acid tails (nonpolar/
hydrophobic)Phosphorylated alcohol (polar/hydrophilic)
Lipid Foundation- Phospholipids
Lipid Foundation- Phospholipids
Fatty Acid side is NONPOLARNonsoluble in water
Phophate side is POLARSoluble in water
Fatty Acid side is NONPOLARNonsoluble in water
Phophate side is POLARSoluble in water
Lipid BilayerLipid Bilayer
Creates barrier to water soluble moleculesInside (tails) of bilayer are nonpolar and therefore insoluble to water
Lipid bilayer is fluid, yet stable.
Creates barrier to water soluble moleculesInside (tails) of bilayer are nonpolar and therefore insoluble to water
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
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”
Transmembrane Proteins extend across lipid
bilayer
Transmembrane Proteins extend across lipid
bilayer These proteins can have both a polar and a nonpolar region.
Enables them to be embedded in the nonpolar (hydrophobic) area of the membrane
Polar regions are anchored in the water
Provide CHANNELS into the cell but only for selected items.
These proteins can have both a polar and a nonpolar region.
Enables them to be embedded in the nonpolar (hydrophobic) area of the membrane
Polar regions are anchored in the water
Provide CHANNELS into the cell but only for selected items.
Proteins act as Cell Identification MarkersProteins act as Cell
Identification MarkersLipids and proteins within the membrane may have a carbohydrate chain attached
These glycolipids and glycoproteins often function as cell ID markers, allowing cells to identify other cells
This is particularly important in the immune system where cells patrolling the body’s tissues identify and destroy foreign invaders such as bacteria or viruses.
Lipids and proteins within the membrane may have a carbohydrate chain attached
These glycolipids and glycoproteins often function as cell ID markers, allowing cells to identify other cells
This is particularly important in the immune system where cells patrolling the body’s tissues identify and destroy foreign invaders such as bacteria or viruses.
Cell Surface ReceptorsCell Surface Receptors
It’s shape fits signal molecules, such as hormones.
Receptors enable cells to detect hormones and a variety of other chemicals in their environment
The binding of a molecule and a receptor initiates a chemical change within the cell.
It’s shape fits signal molecules, such as hormones.
Receptors enable cells to detect hormones and a variety of other chemicals in their environment
The binding of a molecule and a receptor initiates a chemical change within the cell.
Channel ProteinsChannel ProteinsIn some cases the channel proteins simply act as a passive pore. Molecules will randomly move through the opening in a process called diffusion. This requires no energy, molecules move from an area of high concentration to an area of low concentration.
In some cases the channel proteins simply act as a passive pore. Molecules will randomly move through the opening in a process called diffusion. This requires no energy, molecules move from an area of high concentration to an area of low concentration.
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.
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.
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.
Membrane Protein Functions
Membrane Protein Functions
Membrane Protein Functions
Membrane Protein Functions