Why Cells Are Small Essay, Research Paper

Cells are the basic structural and functional units of life. As life on

earth has evolved into organisms of varying complexities, two basic laws

of nature have dictated why cells have remained so small.

Shorter is

faster. This is true both in terms of diffusion and in terms of chemical

and electrical movement. By minimizing the the distance between a cell?s

nucleus and and the numerous proteins and organelles that it must

constantly regulate , a cell is maximizing the speed in which

intercellular communications can take place while providing the ideal

conditions for diffusion: a vital function in the life of a cell.

Like

wise, the surface area and volume of a cell are directly influential in

the efficiency of the cell?s nutrient absorption and waste expulsion

processes. Since the cell membrane of a eukaryotic cell is its only

source of nutrition, it?s surface area must be large enough to allow the

cell?s organelles to receive the materia ls it needs. This is done by

maximizing the surface area to volume ratio. By using the surface area

and volume equations for a sphere(4?r2 and 4/3?r3) you can estimate the

surface area of a small cell(5 ?m) to be nearly 1,200,000 : 1. By

modeling the growth rate of the surface area and volume of a sphere on a

linear graph it?s easily discernible that as the size of the sphere

increases the ratio of surface area to volume dramatically decreases

until finally the volume of the sphere surpasses the surf ace area.

Simply, by minimizing its size, a cell is maximizing the speed at which

it can communicate, the rate at which diffusion can occur, and the amount

of surface area at it?s disposal.

Daniel Veilleux

June 17, 1976

Period 5