Cells, the smallest structures capable of maintaining life
and reproducing, compose all living things, from single-celled
plants to multibillion-celled animals. The human body, which
is made up of numerous cells, begins as a single, newly fertilized
cell.
Almost all human cells are microscopic in size. To give you
an idea how small a cell is, one average-sized adult body,
according to one estimate, consists of 100 trillion cells!
To learn more about cell structure and function, select a
topic listed below.
|