Plasma Membrane

Cell Membrane 1. What is the special lipid found in the plasma membrane? 2. What do you think makes up the plasma membrane?

The Cell Membrane

Main components  Phospholipids  Cholesterol  Proteins Integral Integral Peripheral Peripheral  Glycolipids and glycoproteins  Extra-cellular matrix

Phospholipids The primary component of the plasma membrane is phospholipids  Have two non-polar tails (fatty acids) Hydrophobic – water-fearing Hydrophobic – water-fearing  Have polar phosphate head Hydrophilic – water-loving Hydrophilic – water-loving

Lipid bilayer Like associates with like  Polar head are attracted to polar water environment  Non-polar tails avoid water and stay together  Called phospholipid bilayer

Membrane Proteins Proteins associated with the phospholipid bilayer.  Integral – moves through the bilayer Marker, Receptor, Transport Marker, Receptor, Transport  Peripheral – on one side of the bilayer Enzymes Enzymes

Other parts  Cholesterol Prevent freezing Prevent freezing keep membrane firm keep membrane firm  Glycolipids / Glycoproteins Signaling and cell identity Signaling and cell identity polysaccharide attached to lipid / protein polysaccharide attached to lipid / protein  Extra-cellular matrix External proteins that provide additional support External proteins that provide additional support hold shape hold shape

Fluid Mosaic Model Plasma membrane is dynamic  Behaves more like a liquid than a solid  Pattern of proteins is always changing  Components move laterally Cannot flip between sides Cannot flip between sides