by 
Kaytrip
ANSWERS: 2
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According to the fluid-mosaic model, which is the latest model to describe cell membrane (plasma membrane), the cell membrane is made out of "Phospholipids" which contain phosphorus in it as you can guess. Between these mosaic phospholipid pieces, there are transfer proteins that help the transfer of some large molecules through the membrane. There are also carbohydrates for "recognition". I mean, every cell has some carbohydrate antennes and the white blood cells, defensive organisms etc. recognise the cell by checking the carbohydrate antenne, which works like the barcode of the cell.
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"The cell membrane consists primarily of a thin layer of amphipathic phospholipids which spontaneously arrange so that the hydrophobic "tail" regions are shielded from the surrounding polar fluid, causing the more hydrophilic "head" regions to associate with the cytosolic and extracellular faces of the resulting bilayer. This forms a continuous, spherical lipid bilayer approximately 7 nm thick, barely discernible with a transmission electron microscope. The arrangement of hydrophilic and hydrophobic heads of the lipid bilayer prevent polar solutes (e.g. amino acids, nucleic acids, carbohydrates, proteins, and ions) from diffusing across the membrane, but generally allows for the passive diffusion of hydrophobic molecules. This affords the cell the ability to control the movement of these substances via transmembrane protein complexes such as pores and gates." Source and further information: http://en.wikipedia.org/wiki/Plasma_membrane
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