There is no way DNA molecules could have formed with oxygen present
That is what baffles me. Like before shouting "A-ha!", have you even tried to think it out? Why do you believe that of all things it was the presence of oxygen that should have prevented DNA from assembling itself?
Because without oxygen there would be no life,cells need oxygen.
(cue buzzer) wrong the first life on earth was anaerobic : living, active, occurring, or existing in the absence of free oxygen <anaerobic respiration> <anaerobic bacteria> b : of, relating to, or being activity in which the body incurs an oxygen debt <anaerobic exercise>
Eubacteria and Archaebacteria: the oldest forms of life
Written by Dr. T. M. Wassenaar
Tuesday, 06 January 2009
Bacteria have an extremely important place in the evolution of life. Our knowledge of bacteria helps us understand, observe, and investigate evolution. This exhibits explains what we know about the origin of life on Earth and the role bacteria played and still play in this. As described in this Lecture on the Origin of Life all life originated from a common ancestor (Source: UTDallas). Our other exhibit explains how we can observe mutations in bacteria directly.
Archaeabacteria are a diverse group of bacteria (prokaryotes that do not have a nucleus) and are considered a major group unto themselves. This group is called the Archaea (from Greek, 'old') for short and to distinguish them from the other prokaryotes, all other bacteria are then called Eubacteria.
What are Archaea? They look like bacteria and are genetically similar to bacteria, but in some aspect they are more similar to eukaryotes than to bacteria. For instance, their cell-wall does not contain peptidoglycan (a component of each bacterial cell). There are other characteristics that Archaea share with eukaryotes, however they do not have a nucleus (which all Eukaryotes have). They form a group by themselves.
All prokaryotes thus belong to either the Eubacteria or the Archaebacteria; what is the difference? Add the domain of the eukaryotic organisms (protists, fungi, plants, and animals) and you can classify all living organisms on Earth. Archaebacteria emerged at least 3.5 billion years ago and are amongst the oldest life forms.There are several theories about the exact phylogenetic relationship (what was derived from what) between archaea, eukaryotes, and eubacteria, as can be seen in two versions of the Tree-of-Life. New insights dictate that eubacteria and archaebacteria diverged from one another near the time of the origin of life, and that eukaryotes were derived from archaea that had eubacteria living inside them.
Let's ignore the details. Important is that bacteria (Eu and Archae) have been on earth much longer than eukaryotes; they are probably the oldest forms of life and have populated Earth for most of the time our planet exists. Going back in evolutionary history, the Archaea evolved some 3500 million years ago. Fossiles are mostly not quite as old as that, but occasionally we do find bacterial fossiles. Compare that to the age of the first eukaryotes, 1800 million years ago, or the first animals, 600 million years. Earth is truly the planet of bacteria in this respect!
Eubacteria and Archaebacteria: the oldest forms of life | Evolution
Pink Lake
Why Call a Green Lake “Pink”?
In spite of its name, this lake is not pink. It inherited its name from a family who settled in the region in 1826.
What Exactly Is a Meromictic Lake?
In most lakes, the water mixes completely each year during the spring and fall, under the influence of water density, water and air temperature, and the wind; nutrients and oxygen are distributed evenly.
However, because of it's sheltered position (surrounded by steep cliffs that protect it from the wind) and its shape (small surface area, average depth and bowl-like shape), the lake’s waters do not mix. This is why it is called “meromictic.” Of particular note is the fact that the deepest seven metres of the lake remain without oxygen.
Life in the Lake
In the depths of the lake, an anaerobic prehistoric organism has been able to survive. It is a pink photosynthetic bacterium that uses sulphur instead of oxygen when it transforms sunlight into energy. To maximize the amount of light it captures, without being in contact with oxygen, the colony forms a dense layer that floats seven metres from the bottom.
After the glaciers melted, the region was covered by an arm of the Atlantic Ocean: the Champlain Sea. When it retreated it left the three-spined stickleback. This little saltwater fish (three to five centimetres long) adapted slowly to the lakeÂ’s gradual desalination. In fact, it adapted so well that today it lives in the fresh water of the lake. Desalination usually takes about thirty years. However, Pink Lake is fed only by runoff waters (unique in its watershed area), and so its desalination took place over three thousand years!
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