Cell Membrane/Plasma Membrane Structure Lecture #10

Plasma Membrane Boundary that separates the living cell from it’s non-living surroundings. Phospholipid bilayer Amphipathic - having both: hydrophilic heads hydrophobic tails ~8 nm thick Head: alcohol and phosphate group Tail: fatty acids Phospholipid

Phospholipids can move laterally and allow water and other small molecules to pass through into or out of the cell.  This process is called diffusion which requires no energy because water molecules are moving with the concentration gradient, and not against.

Fluid-Mosaic Model

Plasma Membrane Cholesterol is a lipid located in the plasma membrane which adds fluidity and flexibility to the bilayer

Proteins—For Function Transport Receptors Enzymes Signal Transducers Support

Plasma Membranes Proteins aid in diffusion and cell recognition Peripheral proteins are found only on one side of the membrane Integral proteins = Membrane proteins Lipids or Carbohydrates use proteins to help move across cell membranes carbohydrate chains called glycoproteins attached to help cells in recognize each other and certain molecules.

Plasma Membrane Proteins PROTEINS CAN MOVE IN THE MEMBRANE, TOO!

Membrane Functions Protection Communication Selectively allow substances in Respond/Recognize the environment