Plasma Membrane Essay

1. General Introduction
All cells have a plasma membrane enclosing their cytoplasm, organelles, and every other thing the cell needs to function properly. Organelles, themselves also have membranes. Lipid vesicles are spheres of lipid molecules in bilayers that enclose some sort of aqueous solution, which is what a plasma membrane is. Replicating conditions of cellular membranes in vitro can give us great insights into understanding how cell membranes function in vivo. However, it is not that simple. Many of the cell membrane’s functions are based upon their asymmetric lipid distribution (Pautot et al. 2003).
1.1 Membrane bilayer
The membrane is a complicated part of the cell, made up of a bilayer of many different types of lipids, as well as proteins, that are essential to carry out a variety of processes. Eukaryotic cells invest a large amount of energy and 5% of their genes to synthesize all these types of lipids. The major

There was an uneven distribution of certain types of lipids on the outer leaflet, while there was other types in the inner leaflet. In eukaryotic cells, we see certain trends with certain lipids. It is often seen that SM, PG and PC are found in the outer leaflet, while PS, PI and PE are usually seen in the inner leaflet (Verkleij et al. 1973). These lipids have similar characteristics, but also differ in various ways. This causes the asymmetric distribution of these molecules to have an effect on the behaviors of cell membranes including surface charge, membrane potential, shape, and permeability just to name a few. The specific positions of these lipids are known to have a reason to be there. For example, It has been shown that when PS, normally found on the internal monolayer, is exposed in mammalian cells it is a marker for apoptosis and a signal for disposal by macrophages (Marquardt et al.