Microbes and Metabolism - Environmental Biotechnology: Theory and Application - page 21

Figure2.5 Proteins
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 accepted is based on the sequence
of the DNA coding for rRNA, the rDNA (Stackebrandt and Woese, 1981). For
completeness, it is important to mention the retroviruses which are a group of
eukaryotic viruses with RNA rather than DNA as their genome. They carry the