Beginning of Essay
In the early stages of the twentieth century, little was known about cell membranes. Until the early 1950s, the biological cell membrane was rarely mentioned in scientific literature. It was recognised that something was probably there, but hardly anything about i ....

Middle of Essay
.... the membrane of a frog muscle, Overton found some interesting results. He observed that lipophilic molecules (molecules attracted to fat solvents) could easily cross this cell membrane, however larger lipid insoluble molecules could not. He also observed that small polar molecules could slowly cross the membrane. Other experiments with the likes of hen eggs suggested the presence of a lipid layer in the membrane. These results became known to biologists across the world and it was generally accepted that a semi-permeable lipid membrane surrounded some if not all cells (2). Although this was opening new doors for cell biologists, the information ....