Short answers, pulled from the story.
Robert Hooke coined the term cell in 1665 when he peered through a primitive microscope at a thin slice of cork. This discovery marked the beginning of cell biology despite the misconception that the defining feature of life was a hard, rigid shell for the next century and a half.
Evert Gorter and François Grendel discovered the lipid bilayer structure of the cell membrane in 1925. They extracted lipids from human red blood cells and found the area covered was exactly twice the surface area of the original cells, proving the membrane must be a double layer of lipids.
Seymour Singer and Garth Nicolson proposed the fluid mosaic model of the cell membrane in 1972. This model describes the membrane as a two-dimensional liquid where proteins float and diffuse like icebergs in a sea of lipids, allowing cells to maintain flexibility and move molecules freely.
The cell membrane is composed of phospholipids, glycolipids, and sterols, with phospholipids often making up over 50% of the total lipid content. These amphipathic molecules self-assemble into a bilayer that forms a continuous barrier while cholesterol regulates fluidity in varying temperatures.
Specialized cell membranes like the sarcolemma in muscle cells and the axolemma in nerve cells differ by containing unique structures and densities. The sarcolemma is thicker and contains T-tubules to transmit electrical signals, while the axolemma is densely packed with lipids and proteins to generate action potentials.