|Themes > Science > Zoological Sciences > About Zoology, Generalities > The Symbiotic Theory > Prokaryotes|
characteristic is that prokaryotes are asexual, meaning their
offspring nearly always bear the exact characterisitcs of the
parent cell. (In fact, the cell essentially replicates itself according to
its own DNA and then divides itself from the newly created cell.) Since
the Prokaryotes exhibit this asexual behavior as opposed to sexual
behavior, where a recombination of chromosones occur to form unique
entities (as with humans), evolution of the prokaryotic cell has been
fairly stagnant over its two billion year lifespan. Additionally, at the
time of Symbiosis, prokaryotes were anaerobic, that is, they did
not respirate oxygen as a fundamental necessity to live. As far as nutrition
distribution, the small size of prokaryotes provides a high ratio of
surface area to volume, making diffusion an adequate means for
distributing nutrients throughout the cell.
Prokaryotic cells and fossils have have been found in almost every conceivable environment on the earth, from hot sulfur springs to beneath the ocean floor and within larger cells. Overall, Prokaryotes account for a significant portion of the past and present biomass on earth.