What is a cell? The cell is the functional basic unit of life. It was discovered
by Robert Hooke and is the functional unit of all known living organisms. It is the
smallest unit of life that is classified as a living thing, and is often called the
building block of life. The word cell comes from the Latin cellula, meaning, a
small room. The descriptive term for the smallest living biological structure was
coined by Robert Hooke in a book he published in 1665 when he compared the
cork cells he saw through his microscope to the small rooms monks lived in.

The cell theory, first developed in 1839 by Matthias Jakob Schleiden and
Theodor Schwann, states that all organisms are composed of one or more cells,
that all cells come from preexisting cells, that vital functions of an organism occur
within cells, and that all cells contain the hereditary information necessary for
regulating cell functions and for transmitting information to the next generation of
cells.   Living cells are divided into two types, procaryotic and eucaryotic.   This
division is based on internal complexity. Eucaryotic meaning these cells tend to be
larger than the cells of bacteria, and have developed specialized packaging and
transport mechanisms that may be necessary to support their larger size.
Procaryotic meaning these cells are simple in structure, with no recognizable
organelles. They have an outer cell wall that gives them shape. Just under the rigid
cell wall is the more fluid cell membrane. The cytoplasm enclosed within the cell
membrane does not exhibit much structure when viewed by electron microscopy.

A main purpose of a cell is to organize. Cells hold a variety of pieces and
each cell has a different set of functions. It is easier for an organism to grow and
survive when cells are present. If you were only made of one cell, you would only
be able to grow to a certain size. Also, if you were only one cell you couldn’t have
a nervous...