Just an aside – this is a good little book:
Cell Biology, by Aubrey Stimola (Rosen Publishing, New York, 2011, part of the Science Made Simple series).
It works many metaphors into the discussion, but they are all common to the field and easily shift out to more in depth explanation. Something I had forgotten is where the term ‘cell’ came from and that is an interesting metaphor to have shaped original understanding. Stimola explains:
“In 1665, scientist Robert C. Hooke was the first person to see a cell and recognize it as the basic building block of life. Looking at a thin slice of cork with a compound microscope – an instrument that uses two or more lenses to form enlarged images of very small objects – Hooke saw small, regularly spaced, boxlike structures surrounded by well-defined walls. Because these spaces reminded him of the small rooms that monks lived in, Hooke called them cellulae, from the Latin word cella, or “little room.” What he actually saw were the cell walls of the dead plant cells.” (p.29)