Describe and explain the function of the cell membrane?

The cell membrane consists of a mosaic of proteins and a phospholipid bilayer, with the hydrophobic fatty acid tails orientated inwards and the hydrophilic phosphate heads outwards. The main function is to control which substances move in and out of the cell, also known as selective permeability. Small non-polar molecules such as water can easily pass between the phospholipids whereas larger charged molecules such as Na+ must pass through intrinsic proteins, specifically ionchannels. Cholersterol is also present in the membrane to provide stability.