The basic principles of biological information transfer are simple enough, but
how complex are real living cells? In particular, what are the minimum
requirements? We can get a rough indication by considering the species that
has the smallest known genome the bacterium
Mycoplasma genitalium(Figure 1-14)
environment provides it with many of its small molecules ready-made.
Nevertheless, it still has to make all the large molecules DNA, RNAs, and
proteins required for the basic processes of heredity. It has only 477 genes in
its genome of 580,070 nucleotide pairs, representing 145,018 bytes of
information about as much as it takes to record the text of one chapter of this
book. Cell biology may be complicated, but it is not impossibly so.The minimum number of genes for a viable cell in today's environments is
probably not less than 200 300. As we shall see in the next section, when we
compare the most widely separated branches of the tree of life, we find that a
core set of over 200 genes is common to them all.. This organism lives as a parasite in mammals, and its
EmoticonEmoticon