annonCells are the basic structural and functional units of life. As life onearth has evolved into organisms of varying complexities, two basic lawsof nature have dictated why cells have remained so small. Shorter isfaster. This is true both in terms of diffusion and in terms of chemicaland electrical movement.
By minimizing the the distance between a cellsnucleus and and the numerous proteins and organelles that it mustconstantly regulate , a cell is maximizing the speed in whichintercellular communications can take place while providing the idealconditions for diffusion: a vital function in the life of a cell. Likewise, the surface area and volume of a cell are directly influential inthe efficiency of the cells nutrient absorption and waste expulsionprocesses. Since the cell membrane of a eukaryotic cell is its onlysource of nutrition, its surface area must be large enough to allow thecells organelles to receive the materia ls it needs. This is done bymaximizing the surface area to volume ratio.
By using the surface areaand volume equations for a sphere(4r2 and 4/3r3) you can estimate thesurface area of a small cell(5 m) to be nearly 1,200,000 : 1. Bymodeling the growth rate of the surface area and volume of a sphere on alinear graph its easily discernible that as the size of the sphereincreases the ratio of surface area to volume dramatically decreasesuntil finally the volume of the sphere surpasses the surf ace area.Simply, by minimizing its size, a cell is maximizing the speed at whichit can communicate, the rate at which diffusion can occur, and the amountof surface area at its disposal.Daniel VeilleuxJune 17, 1976Period 5
