1. The problem statement, all variables and given/known data Explain why carohydrates are found attached to integral membrane proteins on the outside, but almost never on the inside (cytoplasmic face) of cell membranes. 2. Relevant equations ----------- 3. The attempt at a solution Carbohydrates bond with integral membrane proteins on the outside to facilitate cell-to-cell recognition. It helps cells realize if they are the same or if they are not the same, whether it is something the cell wants, or something that may be harmful to the cell, etc. What I can not find anywhere is any reasoning on why these carbohydrates are not on the inside? My assumption would be that if they were on the inside then anything could get into the cell and by the time the carbohydrate realized it wasn't supposed to be there it would be too late. Also, the extracellular matrix is hydrophilic and so are carbohydrates... whereas to get through the membrane to the the inside of the cell you would need to be nonpolar so you could get through the hydrophobic phosolipid bilayer.