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The First Living Cells


An electron micrograph of Bacteria
Image courtesy of JPL/NASA
The first beings were probably much like coacervates. As a group, these bacteria were heterotrophic , meaning that they ate food which came from somewhere else. Because there was virtually no oxygen in the atmosphere at this time, these bacteria did not breathe oxygen. The fossils of some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.

For food, these early bacteria probably consumed naturally occurring amino acids. Amino acids, sugars, and other organic compounds formed spontaneously in the atmosphere then dissolved in liquid water. Upon digesting these molecules, early bacteria produced methane and carbon dioxide as waste products.

Over time, new life forms evolved which were able to get their energy from a different source -- the Sun!

The First Living Cells


An electron micrograph of Bacteria
Image courtesy of JPL/NASA
The first beings were probably much like coacervates. As a group, these bacteria are called heterotrophic anaerobes (ann-air-robes). Because there was virtually no oxygen in the atmosphere at this time, these bacteria were necessarily anaerobic, meaning they did not breathe oxygen. Heterotrophs, meaning "other feeders", are simply organisms that cannot make their own food. So "heterotrophic anaerobes" means they were creatures which ate some naturally occurring food and did not breathe oxygen. The fossils of some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.

To create energy, these early bacteria probably consumed naturally occurring amino acids. Amino acids, sugars, and other organic compounds formed spontaneously in the atmosphere then dissolved in liquid water. Upon digesting these molecules, early bacteria produced methane and carbon dioxide as waste products. Fermenting bacteria would be an example from today of what these early creatures might have been like. To make beer you combine barley or wheat and water. The broken down barley and wheat turns into sugar. Bacteria eat the sugars and produce alcohol and carbon dioxide gas as waste products. In the early Earth, the alcohol and carbon dioxide became part of the natural environment.

Over time, new life forms evolved which were able to get their energy from a different source -- the Sun!

The First Living Cells


An electron micrograph of Bacteria
Image courtesy of JPL/NASA
The first beings were probably much like coacervates. As a group, these bacteria are called heterotrophic anaerobes. Because there was virtually no oxygen in the atmosphere at this time, these bacteria were necessarily anaerobic, meaning they did not breathe oxygen. Heterotrophs, meaning "other feeders", are simply organisms that cannot make their own food. The fossils of some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.

To create energy, these early bacteria probably used a chemical process called enzymatic catalysis to consume naturally occurring amino acids, sugars, and other organic compounds that had formed spontaneously in the atmosphere then dissolved in liquid water. Because of this chemical process, scientists sometimes call these beings chemo-heterotrophic anaerobes. Upon digestion of these molecules, early bacteria produced methane and carbon dioxide as waste products. Fermenting bacteria would be today's analog of these early creatures. To make beer, barley or wheat is combined with water to make a carbohydrate mash. Bacteria eat the sugars and produce alcohol and CO2 as waste products. In the early Earth, the alcohol and carbon dioxide became part of the natural environment.

Over time, new life forms evolved which were able to get their energy from a different source -- the Sun!

The First Living Cells

The first beings were probably much like coacervates. As a group, these bacteria are called heterotrophic anaerobes. They were necessarily anaerobic, because there was virtually no oxygen in the atmosphere at this time. Heterotrophs, meaning "other feeders", are organisms that cannot make their own food. The fossils of some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.

These early bacteria probably used enzymatic catalysis to consume naturally occurring amino acids, sugars, and other organic compounds that had formed spontaneously in the atmosphere then dissolved in the ocean. Because of the chemical process employed by these early creatures to convert food, they are sometimes called chemo-heterotrophic. As part of the metabolic process, their waste products included methane and carbon dioxide. Fermenting bacteria would be today's analog of these early creatures. In making beer, barley or wheat is combined with water to produce a carbohydrate mash. Bacteria consume the sugars and produce alcohol and CO2 as waste products. Early bacteria in an anaerobic environment probably also consumed N2, producing NH4+, as well as formaldehyde and SO42-, producing H2S (pyrite).

Over time, new life forms evolved which were able to get their energy from the Sun.

Bacteria
Image courtesy of JPL/NASA



Last modified December 17, 1998 by the Windows Team

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