Post on 07-Aug-2015
Presented by: Nisha Lakra1st sem Applied GeneticsBrindavan College
Presented to : Mr. Aditya Sathyan Cellular Physiology Brindavan College
Introduction
• Boundary that separates the living cell from it’s non-living surrounding.
•The cell membrane is selectively permeable.
•It consists of the phospholipid bilayer with embedded proteins.
•Most widely accepted model is Fluid-Mosaic Model
Oligosaccharides
CytoplasmCytoplasm
Membrane Proteins
Cholesterol
OuterSurface
Fluid Mosaic Modelof Membrane Structure
PhospholipidBilayer
Macromolecules found in Membranes
• Lipids– Phospholipid bilayer– Cholesterol
• Proteins– Transport proteins– Receptor proteins– Recognition proteins
• Carbohydrates– Oligosaccharides on glycoproteins
The plasma membrane “fluid” is a double layer of phospholipids.
The plasma membrane “mosaic” is a collection of proteins.
Transport Processes• Movement of substances across the cell
membrane
• Passive transport– No energy input required– Simple Diffusion, Facilitated Diffusion, Osmosis
• Active transport– Substances move from [low][high]– Protein carriers, Endocytosis, Exocytosis
Simple Diffusion(extracellular fluid)
(cytoplasm)
Some molecules
diffuse freelyacross
Some moleculesdiffuse freely
across
(lipid soluble molecules, CO2, O2, H2O )
Now known to require transport proteins called aquaporins
Facilitated Diffusion: Use of Carriers to Assist with Diffusion
Carrier proteinhas binding sitefor molecule
Molecule entersbinding site
Carrier protein changesshape, transportingmolecule across membrane
Carrier protein resumesoriginal shape
(Inside Cell)(Inside Cell)
(OutsideCell)
(OutsideCell)
DiffusionChannelProtein
DiffusionChannelProtein
Diffusion
Gradient
Molecule inTransit
Molecule inTransit
Osmosis• Diffusion of water across a differentially permeable
membrane• Water moves from [high] [low]
Normal RBCs
Isotonic Solution
The Effects of Osmosis
Equal movement of waterinto and out of cells
Net movement ofwater out of cells
Net movement ofwater into cells
Shriveled RBCs
Swollen RBCs
Hypertonic Solution Hypotonic Solution
Active Transport with Protein Carrier
Inside CellInside Cell
Outside CellOutside Cell
EnergyProviderEnergy
ProviderSpent Energy
ProviderSpent Energy
Provider
TransportedMolecule
TransportedMolecule
1 2 3 4
Endocytosis
(extracellular fluid)
Pinocytosis
vesicle containingextracellularfluid)(cytoplasm)
12 3
cell
(extracellular fluid)
(cytoplasm)
1
23 4
coatedpit forming
Receptor-mediatedEndocytosis
Phagocytosis
coatedvesicle
nutrientsreceptors
food particle
pseudopodparticle enclosedin food vacuole
Exocytosis
(cytoplasm)
1
Vesicle
(extracellular fluid)
plasma membrane
2
SecretedMaterial
3
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