History of cell membrane theory
By the mid 19th century, this question was being actively investigated and Moritz Traube noted that this outer layer must be semipermeable to allow transport of ions.[1] Traube had no direct evidence for the composition of this film, though, and incorrectly asserted that it was formed by an interfacial reaction of the cell protoplasm with the extracellular fluid.Hans Horst Meyer and Ernest Overton independently noticed that the chemicals which act as general anesthetics are also those soluble in both water and oil.[6] This “flaw” remained unanswered for nearly half a century until the discovery that specialized molecules called integral membrane proteins can act as ion transportation pumps.Gorter and Grendel approached the problem from a different perspective, performing a solvent extraction of erythrocyte lipids and spreading the resulting material as a monolayer on a Langmuir-Blodgett trough.[8] Later analyses of this experiment showed several problems including an incorrect monolayer pressure, incomplete lipid extraction and a miscalculation of cell surface area.Their theory was also incorrect in that it ascribed the barrier properties of the membrane to electrostatic repulsion from the protein layer rather than the energetic cost of crossing the hydrophobic core.After staining with heavy metal labels, Sjöstrand et al. noted two thin dark bands separated by a light region,[11] which they incorrectly interpreted as a single molecular layer of protein.A more accurate interpretation was made by J. David Robertson, who determined that the dark electron-dense bands were the headgroups and associated proteins of two apposed lipid monolayers.[14] Harvey and James Danielli (1939) proposed a lipid bilayer membrane covered on each side with a layer of protein to account for measurements of surface tension.In 1935, Karl Lohmann discovered ATP and its role as a source of energy for cells, so the concept of a metabolically-driven sodium pump was proposed.By “painting” a reconstituted lipid solution across an aperture, Mueller and Rudin were able to determine that the resulting bilayer exhibited lateral fluidity, high electrical resistance and self-healing in response to puncture.In spite of these limitations, the fluid mosaic model remains a popular and often referenced general notion for the structure of biological membranes.Some criticisms of the membrane theory developed in the 1930s, based on observations such as the ability of some cells to swell and increase their surface area by a factor of 1000 (as in adipose tissue).
Cell theorymicroscopy observationscell membraneanestheticlipid bilayerproteinsRobert Hookecell wallMoritz TraubeGeorg Hermann QuinckeHans Horst MeyerErnest Overtonanesthetics“lipoid theory of narcosis.”phosphatidylcholinecholesterolintegral membrane proteinsMembrane modelscapacitanceerythrocytehydrocarbonbilayerLangmuir-Blodgett troughDavson and Danielliglobular proteinsadsorptionelectrostatichydrophobicelectron microscopyorganellesemipermeable membranesolventsolutemoleculesosmosisphysiologicalbotanistWilhelm Pfeffercell physiologyplasma membranepotassiumdilute solutionhemolysiserythrocyteslipid membraneanionsLeonor Michaelisadsorbedelectrostatic repulsionmembrane potentialJames Danielliradioactive tracersdynamic equilibriumion gradientssodium pumpHodgkinHuxleycellular membrane potentialsFluid mosaic modelfluorescentSingerNicolsonnuclear porecytoskeletonGilbert Lingprotoplasmdilute solutionsgelatinadipose tissuefibrinJacques LoebColumbia University Biological SeriesH. F. OsbornE. B. WilsonBibcode