Cell Size and Scale

This is a fun little learning tool, provided by The University of Utah.  Use the slider bar to zoom smaller and smaller in scale, from 12 millimeters (coffee bean) to 140 picameters (carbon atom), and track progress with the graph in the upper left.  And if something looks fishy about that sperm cell…

How can an X chromosome be nearly as big as the head of the sperm cell?

No, this isn’t a mistake. First, there’s less DNA in a sperm cell than there is in a non-reproductive cell such as a skin cell. Second, the DNA in a sperm cell is super-condensed and compacted into a highly dense form. Third, the head of a sperm cell is almost all nucleus. Most of the cytoplasm has been squeezed out in order to make the sperm an efficient torpedo-like swimming machine.

Link via Twisted Sifter