Plasma Membrane ~ Structure and Functions

Basic Purposes
1. present in both eukaryotic and prokaryotic cells
2. works as a barrier between the inner and outer surface of a cell
3. Animal Cells
  1. Present in the outer most layer of the cell
4. Plant cells
  1. Present just beneath the cell wall
Structure of the Plasma Membrane
Components
1. Proteins
  1. Controls what enters and leaves the cell
    1. Some form channels which allow small charged particles through
    2. Carrier proteins transport large molecules and charged particles across the membrane through active transport and facilitated diffusion
    3. Act as receptors for molecules (e.g. hormones) used in cell signalling)
2. Lipids like Glycolipid (Lipids with a carbohydrate attached)
  1. attached to phospholipids along with the sugar chains
3. Phospholipid Bilayer
  1. create a partially permeable membrane, which allows only certain substances to diffuse through the membrane.
  2. The centre of the bilayer is hydrophobic so no water - soluble substances can dissolve through
  3. Fat-soluble substances can dissolve straight through the membrane
4. Cholestorol
  1. maintains the fluidity of cell surface membrane.
  2. A type of lipid present in all cells (except bacterial)
  3. They bind to the hydrophobic tail of phospholipds
    1. Making the membrane less fluid due to being tightly packed
  4. Has hydrophobic sections making a further barrier for substances
Phospholipids
Water is a polar molecule but due to being small can diffuse by osmosis through the cell

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Plasma Membrane ~ Structure and Functions

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	Created by Lauren Goldson over 8 years ago