Comparison of the Animal Cell with Precellular Forms of Life The cell is a complicated organism that required many hundreds of millions of years to develop
after the earliest form of life, an organism similar to the present-day virus, first appeared on earth.
Figure 2-10 shows the relative sizes of (1) the smallest known virus, (2) a large virus, (3)
a rickettsia, (4) a bacterium, and (5) a nucleated cell, demonstrating that the cell has a diameter
about 1000 times that of the smallest virus and, therefore, a volume about
Figure 2-8 Microtubules
teased from the flagellum of a sperm.
(From Wolstenholme GEW, O’Connor M, and the
publisher,
JA Churchill, 1967. Figure 4, page 314. Copyright the Novartis
Foundation,
formerly the Ciba Foundation.)
Endoplasmicreticulum
Nucleoplasm
CytoplasmNuclear
envelopeouter
and inner
membranesPores
NucleolusChromatin material (DNA)
Figure 2-9 Structure of the nucleus
1 billion times that of the smallest virus.
