The Sun, the Earth, and the Evolution of the Earth’s Atmosphere - Air Pollution and Global Warming: History, Science, and Solutions - page 37

radiative conditions. For example, one strain of bacte-
ria found today, Strain 121 ,lives near a hydrothermal
vent in the northeast Pacific Ocean and can grow at a
temperature of up to 121 ◦ C. Another strain in Siberian
permafrost can grow at a temperature as low as

Table 2.3. Timeline of evolution on Earth and its
atmosphere

Billion
years ago Event

10 ◦ C.
Ferroplasma acidarmanus lives in acidic waters with a
pH near 0 at Iron Mountain, California, and Deinococ-
cus radiodurans can survive a radiation dose one thou-
sand times higher than that lethal to humans (Cockell
et al., 2007).
Living organisms today are classified according to
their energy source, electron donor source, and carbon
source (Table 2.4). Organisms that obtain their energy
from sunlight are referred to as phototrophs .Those
that obtain their energy from oxidation of a chem-
ical are chemotrophs .Organisms that use inorganic
compounds, such as carbon dioxide [CO 2 (g)], molecu-
lar hydrogen [H 2 (g)], hydrogen sulfide [H 2 S(g)], water
[H 2 O(g)], the ammonium ion [NH 4 + ], or the nitrite
ion [NO 2 − ], as electron donors are lithotrophs .Those
that use organic compounds as electron donors are
organotrophs .Organisms that obtain their carbon from
CO 2 (g) are autotrophs .Those that obtain their carbon
from organic compounds are heterotrophs .
Most cyanobacteria, green plants, and algae obtain
their energy from sunlight, their carbon from carbon
dioxide, and use water as the electron donor, and thus
are photolithotrophic autotrophs (Figure 2.8). Some

−

4.6 Formation of Earth

4.6-4.4 Earth's first atmosphere with H, He

4.3-3.8 Earth's crust formation and outgassing

4.0 NH 3 (g) photolysis to form N 2 (g) becomes

important

3.5 Abiotic synthesis of amino acids

3.5 First prokaryotic bacteria

3.5 Fermenting bacteria produce CO 2 (g)

3.5 Anoxygenic photosynthesis by sulfur

cyanobacteria

3.5-2.8 Oxygenic photosynthesis by cyanobacteria

3.2 Dentrifying bacteria produce N 2 (g)

2.9 Methanogenic bacteria produce CH 4 (g)

2.45 Great Oxygenation Event

2.1-1.85 First eukaryotic bacteria evolve

1.8 Nitrifying bacteria convert NH 3 (g) to

NO 3 −

1.5 Nitrogen-fixing bacteria convert N 2 (g) to

NH 3 (g)

0.57 First shelled invertebrates

0.43-0.5 First primitive fish

0.395-0.43 First land plants

glycine , a-alanine , and b-alanine (Miller, 1953). The
amino acids could not have been produced from exist-
ing life because the boiling water and the presence of
acids during the experiment would have extinguished
such life. Later experiments showed that the same
results could be obtained with different gases and with
UV radiation as well. In all cases, much of the ini-
tial gas had to be highly reduced (Miller and Orgel,
1974).
Thus, in the prebiotic atmosphere, the amino acids
required for the production of deoxyribonucleic acid
(DNA) were first developed. About 3.5 b.y.a., the
first microscopic cells containing DNA evolved. These
prokaryotic cells contained a single strand of DNA but
no nucleus. Today, prokaryotic microorganisms include
many bacteria and blue-green algae.
Prehistoric bacteria were able to adapt to the evolv-
ing, harsh climate of the early Earth just as many bac-
teria today exist under extreme temperature, acidity, or

Figure 2.8. Hot sulfur springs in Lassen National Park,
California. Boiling water of geothermal origin is rich in
hydrogen sulfide. Photolithotrophic autotrophic
bacteria thrive in the springs and oxidize the
hydrogen sulfide to sulfuric acid, which dissolves the
surrounding mineral and converts part of the spring
into a “mud pot.” The steam contains mostly water
vapor, but hydrogen sulfide, sulfuric acid, and other
gases are also present. Courtesy Alfred Spormann,
Stanford University.