BIOL1006 Lecture Notes - Lecture 15: Lipid Bilayer, Phospholipid, The Membranes
Document Summary
Despite differences in structure and function, all living cells in multicellular organisms have a surrounding plasma membrane. As the outer layer of your skin separates your body from its environment, the plasma membrane separates the inner contents of a cell from its exterior environment. The plasma membrane can be described as a phospholipid bilayer with embedded proteins that controls the passage of organic molecules, ions, water, and oxygen into and out of the cell. Wastes also leave the cell by passing through the membrane. The eukaryotic plasma membrane is a phospholipid bilayer with proteins and cholesterol embedded in it. The cell membrane is an extremely pliable structure composed primarily of two adjacent sheets of phospholipids. Cholesterol, also present, contributes to the fluidity of the membrane. A single phospholipid molecule consists of a polar phosphate head, which is hydrophilic, and a non-polar lipid tail, which is hydrophobic. Unsaturated fatty acids result in kinks in the hydrophobic tails.
