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E u c a r y a 10 9 a
A n i m a l e s 0.5
P l a n t a e
Chlorophyta
Rhodophyta

Lichen

Basidiomycota
F u n g i
B a c t e r i a Ascomycota
Phaeophyta
Proteobacteria A r c h a e a 1.2
2.1
Cyanobacteria
3.0

3.5
LUCA
Planet Earth 4.7
Figure 1. Phylogenetic tree. Time scale in billion years. LUCA = last uniform common
ancestor.

“Active acetic acid” readily reacts with amino acids (formed in the primordial broth by electric
discharge; and/or in interstellar clouds by irradiation and carried to Earth confined in the ice
cores of comets) to form peptides, which chiral selection and further polymerise on chiral
matrices provided by certain clays and quartz minerals. Concomitantly, nucleobases can form
under primordial and interstellar conditions, and polymerise to RNA, unique molecules which
not only store information and transform this information into proteins, but also can act – like
proteins – as enzymes (so-called ribozymes). The first life forms, primitive cellular organisms
capable of self-sustenance and self-replication, are actually believed to have been members of
an “RNA world”, which later has been replaced by our DNA world.

Fig. 2 classifies the bio-elements: Along with the “organic elements” (C, H, O, N, S), building
up bio-mass, many “inorganic elements” play an important role in the physiological context.
Some of these inorganic elements, such as Fe, Cu and Zn, are present in (practically) all
organisms, others are important for a restricted number of organisms only. An additional group
of elements are used for diagnostic or therapeutic applications.

Figure 2. Periodic Table of the bio-elements: elements building up bio-mass, additional
essential elements, essential for some groups of organisms, medicinally important elements.