Cell MembraneMaintains homeostasis by regulating the movement of molecules in

and out of the cell

Fluid Mosaic Model

• Polar heads are orientated to the aqueous solution (inside and outside of cell)

• Non polar tails are orientated towards one another

• Integral proteins are embedded to form a mosaic

Membrane Proteins

• Channel Proteins (transport)• Carrier Proteins (transport)• Receptor Proteins (signal transduction)• Cell Recognition Proteins (glycoprotein)• Enzymatic Proteins• Intercellular Joining• Attachment for Cytoskeleton

http://www.wisc-online.com/objects/index_tj.asp?objID=AP1101

Membrane Permeability

• Impermeable• Permeable• Differentially/Selectively Permeable

Terms to know

• Osmotic pressure• Turgor Pressure• Tonicity• Isotonic• Hypotonic• Hypertonic• Plasmolysis• Creanation

Methods of Transport Across The Cell Membrane

Passive Transport

http://highered.mcgraw-hill.com/sites/dl/free/0072421975/196646/lw02_diffusion_final.html

Rate of Diffusion

• Temperature increase• Increased concentration gradient• Increased membrane permeability• Smaller molecule size

Osmosis

• Diffusion of water through a semi permeable membrane

http://www2.nl.edu/jste/osmosis.htm

http://ccollege.hccs.edu/instru/Biology/AllStudyPages/Diffusion_Osmosis/Elodeagif.swf

Facilitated Transport

• Movement of molecules along the concentration gradient with the aid of carrier proteins

Active Transport

• Movement of molecules against the concentration gradient using carrier proteins and ATP

Active Transport

• Endocytosis– Phagocytosis– Pinocytosis

• Exocytosis

Animation Review