Why are Cells so Small?
This post will cover the balance of surface area to volume of cells for Prelim Biology.
What is the Balance of Surface Area to Volume Ratio?
For a cube, the surface area is the sum of the area of all the individual faces while the volume is the capacity of the cube. For a cell, it is the same thing except it is the external area of the cell and the internal volume. A ratio can be formed by comparing surface area and volume which is called the surface area to volume ratio (surface area: volume).
This video will explain it in a little more detail.
How Does This Relate to the Size of a Cell?
Why can’t cells just grow to the size of humans? What limits them? The answer, the surface area to volume ratio.
A cell needs enough surface area to efficiently diffuse substances to the inside of the cell. Additionally, surface area and volume do not increase at the same rate, volume increases much faster. So a bigger cell will have a smaller surface area to volume ratio while a smaller cell will have a larger surface area to volume ratio.
This video will go into more depth about why cells are small.
This video goes through an experiment that is often used to demonstrate why a large surface area to volume ratio is important (you will likely perform this in class at some point).
Want to learn more? Check out more of our Preliminary Biology resources here!