Cell MembranePlasma Membrane Structure Lecture 10 Plasma Membrane

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 Phospholipid ~8 nm thick Head: alcohol and phosphate group Tail: fatty acids

• 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