an idea (a cell theory)

The intracellular ionic composition of modern day cells could potentially be traced back to the mineral composition of ancient seawater.  Although analysis of ancient seawater is in the early stages of development, it is thought to have elevated levels of k, Ca, Mg, and sulfate do to either a more rapid rate of seafloor spreading or more subfloor fluid flow such as in the convection cells of brine springs.  Ancient lakes and seabeds are modernday mines for K and its salts, such as the Dead Sea (4.4% KCl).  Ancient corals are found to have different skeletal composition than modern day corals, indicating a different ancient sea environment. (Johns Hopkins Univeristy, 2004.)

Theoretically, the original cell developed with the compilation of a lipid monolayer membrane.  This original membrane would have ‘wrapped’ around what was then ancient seawater.  Cells of this era would have evolved to utilize the minerals present in this ancient seawater (now intracellular fluid).  In this scenario, a seawater (and cellular) composition of high K levels, and lower Na levels would reflect the gradients of these ions in modern cells.

After initial cellular development, it is possible the mineral (ion) concentrations of the extracellular (extraorganismal) environment changed, causing the cell (organism) to adapt to keep its internal levels the same.  Ion pumps and cotransporters such as the Na/K Atpase could be such adaptational mechanisms.  As K began to diffuse out of the cell, due to lowered external levels due to environmental changes, the cell could have responded with complementary proteins along the membrane, which could have been precursors to the Na/K ATPase channels.

            Archaea bacteria is thought to be the original life form, and would have evolved in ancient seawater, or in a brine seafloor vent.  Some characteristics known about Archaea are similar to Eukaryotic mechanisms.  Archaea flagella motors are powered by proton gradient.  This is similar to ATP production in modern mitochondria.  Energy in known Archaea is provided by redox rxns – in the form of an electron transport chain such as in mitochondria.  ATP production is seemingly one step away from the development of an ATPase.  Archaea have a single phospholipid monolayer membrane with protein.  A single phosopholipid layer would more easily derive a protein channel allowing for controlled flow of K (and Na).    The combination of ATP production via an electron transport chain, a phospholipid monolayer protein membrane, and the diffusion of K ions could result in an ATPase membrane channel.



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