The Early Earth Atmosphere and Early Life Catalysts - The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment - page 1

Chapter 1
The Early Earth Atmosphere
and Early Life Catalysts

Sandra Ignacia Ram ´ rez Jim ´ nez

Contents
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1 THE EARLY EARTH ATMOSPHERE AND LITHOSPHERE . ........................ 2

1.1 Earth's Internal Structure . ............................................................ 3

2 CATALYSTS IN THE EARLY EARTH . ................................................. 4

3 CLAYS AS POSSIBLE CATALYSTS IN THE SYNTHESIS
OF BIOMOLECULES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 GENERAL CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

ABBREVIATIONS ............................................................................. 13

ACKNOWLEDGMENT . . . . . . . . . . ............................................................. 13

REFERENCES . ................................................................................. 13

Abstract Homochirality is a property of living systems on Earth. The time, the
place, and the way in which it appeared are uncertain. In a prebiotic scenario two
situations are of interest: either an initial small bias for handedness of some
biomolecules arouse and progressed with life, or an initial slight excess led to the
actual complete dominance of the known chiral molecules. A definitive answer can
probably never be given, neither from the fields of physics and chemistry nor
biology. Some arguments can be advanced to understand if homochirality is
necessary for the initiation of a prebiotic homochiral polymer chemistry, if this
homochirality is suggesting a unique origin of life, or if a chiral template such as a
mineral surface is always required to result in an enantiomeric excess. A general
description of the early Earth scenario will be presented in this chapter, followed by
a general description of some clays, and their role as substrates to allow the
concentration and amplification of some of the building blocks of life.