The Plasma Membrane

The Plasma Membrane

Ms. Nina Abdel-Naby

The Plasma Membrane 

Maintains homeostasis in Cell: controls nutrients going into the cell (examples….) controls waste leaving the cell (examples….) Membrane is selectively permeable (selects what goes into or comes out of the cell) 

Structure of Plasma Membrane Composed of phospholipids: made up of a glycerol, 2 fatty acid chains, and a phosphate group

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Fatty acid tails are hydrophobic: water hating Phosphate + glycerol head is hydrophilic: water loving

Phospholipid bilayer 

Plasma membrane is composed of 2 layers of phospholipids

Components of Cell  Membrane Phospholipid bilayer  

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Cholesterol Proteins span entire membrane are called transport proteins: regulate entry and exit of certain substances Proteins on the surface usually have carbohydrates attached to them and act as chemical signals Proteins at the inner surface attach membrane to internal support structure

Fluid Mosaic model 

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Phospholipids can move within the membrane Proteins move among the phospholipids Cholesterol prevents fatty acid tails from sticking together

It’s Fear of Punishment that makes man behave.