Body is made of different collection of cell types organized into different tissue types. These collections of tissues make organs and organs make systems. Different cells have different functions, different processes they mediate and each have specialised functions. Eukaryotic cell: generalised cell, animal & plant cell. Plasma membrane: part of the cell that allows communication with the rest of the body. Has a lipid group: 2 fatty acid chains. Hydrophilic, polar and pointing outside (ecf or cytoplasm). Have many functions and may act as receptors (eg. Membranes: was properly described in 1972. [ ] arranged in anamphipathic structure, that is, with the ionic and highly polar groups protruding from the membrane into the aqueous phase, and the nonpolar groups largely buried in the hydrophobic interior of the membrane. This diagram made in 1972 is pretty similar to what we study now. This image shows some integral proteins which have different functions.