An electron micrograph of Bacteria
Image courtesy of JPL/NASA
The First Living Cells
The first beings were probably much like coacervates
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.
, 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!
Shop Windows to the Universe Science Store!
The Spring 2010 issue of The Earth Scientist
, focuses on the ocean, including articles on polar research, coral reefs, ocean acidification, and climate. Includes a gorgeous full color poster!
You might also be interested in:
In the warm primordial ocean, aggregates of amino acids, proteins, and other hydrocarbons came together into a form called *coacervates*. Amino acids will spontaneously form coacervates in the same way...more
Carbon dioxide (CO2) is a kind of gas. There isn't that much carbon dioxide in Earth's atmosphere, but it is still very important. Carbon dioxide is a greenhouse gas. That means it helps trap heat coming...more
Over a very long time, gradual changes in the earliest cells gave rise to new life forms. These new cells were very different from the earlier heterotrophs because they were able to get their energy from...more
Eventually, photosynthesis by the earliest forms of plant life (a form of life capable of feeding itself instead of feeding off of others) began to produce significant amounts of oxygen. One important...more
Scientists have found a type of amino acid in a sample returned from a comet. Amino acids are the building-blocks of proteins. Proteins are one of the most important types of molecules in living creatures....more
Jupiter's atmospheric environment is one of strong gravity, high pressure, strong winds, from 225 miles per hour to 1000 miles per hour, and cold temperatures of -270 degrees to +32 degrees (freezing temperature)....more
In July, 1996, it was announced that Dr. David McKay, along with a team of scientists at Johnson Space Center (a division of NASA), had discovered possible fossils of bacteria in a meteorite named ALH84...more