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abiogenesis

Friday 22 May 2009

In the natural sciences, abiogenesis is the study of the origin of life, the study of how life on Earth could have arisen from inanimate matter.

Amino acids

Amino acids, often called "the building blocks of life", occur naturally, due to chemical reactions unrelated to life.

In all living things, these amino acids are organized into proteins, and the construction of these proteins is mediated by nucleic acids. Thus the question of how life on Earth originated is a question of how the first nucleic acids arose.

Nuclei acids

The exact sequence of chemical events that led to the first nucleic acids is not known. Several hypotheses about early life have been proposed, most notably the iron-sulfur world theory (metabolism without genetics) and the RNA world hypothesis (RNA life-forms).

Living organisms

The first living organisms on Earth are thought to be single cell prokaryotes. The oldest ancient fossil microbe-like objects are dated to be 3.5 Ga (billion years old), just a few hundred million years younger than Earth itself.

By 2.4 Ga, the ratio of stable isotopes of carbon, iron and sulfur shows the action of living things on inorganic minerals and sediments and molecular biomarkers indicate photosynthesis, demonstrating that life on Earth was widespread by this time.

Links

- Wikipedia