Microbes and Metabolism 21bacteria where they replicate, thus making the metabolic capability they carry,
transferable. Bacteria show great promiscuity with respect to sharing their DNA.
Often, bacteria living in a contaminated environment, themselves develop addi-
tional degradative capabilities. The source of that genetic information new to
the organism, whether it is from modification of DNA within the organism or
transfer from other microbes, or DNA free in the environment, is a source of hot
debate between microbiologists.
DNA not only codes for RNA which is translated into proteins but also for
RNAs which are involved in protein synthesis, namely transfer RNA (tRNA) and
ribosomal RNA (rRNA), also, small RNAs which are involved in the processing
of rRNA. These are illustrated in Figure 2.6. There have been many systems used
to describe the degree of relatedness between organisms, but the most generally
Figure 2.6 Storage and expression of genetic information