Single-Celled Species' Genome As Complex As Ours?
analysis of the [0]genome of a single-celled species known as
[1]Tetrahymena thermophila. This ciliate (like the Paramecium people
look
at in school) has some 27,000 genes, or nearly as many as humans. And
despite existing as a single cell, this spcies encodes fantastic
complexity and unusual features. For example, it has a primitive immune
system that prevents the invasion of foreign DNA. Also, it is able to
cordon off its germ cell lineage much as humans do with sperm and eggs.
But Tetrahymena does this by having two nuclei within each cell, with
one
of the nuclei being held in reserve for sex. Basically, this species
uses
its genome complexity to function like a single celled chameleon,
changing its shape and its properties in response to the changing
environment. For example, when a new nutrient shows up in its
neighborhood this species can build a kit to suck the nutrient in,
degrade it, and turn it into cellular biomass quickly. Thus whereas
humans use their genomic complexity in part to create a stable
environment for the body, this species simply uses a genomic swiss army
kit to make do with whatever environment it encounters."