Britannica Educational Publishing 
Cell [PDF ebook] 

A single cell can be a self-sustaining organism or one of trillions in a larger life form. Though visible only with the help of a microscope, cells are highly structured entities that perform a myriad of functions in every living thing and store critical genetic information. This fascinating volume examines the organization of various types of cells and provides an in-depth look at how cells operate alone to generate new cells and act as part of a larger network with others.