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DNA holds genetic information and holds the key to the evolution of living organisms. Transcription and translation mechanisms enable living cells to process information encoded in DNA. To that end, transcription and translation are fundamental mechanisms needed to enable the evolution of organisms. Molecular machines (enzymes) carry out these mechanisms by reading the information in DNA and using it to construct proteins.

Did the first living cell contain the machinery needed for translation and transcription? or Did they evolve over time?

EDIT: Edited the question to narrow the scope.

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  • $\begingroup$ Thank you for your feedback. Please let me know if the question needs further editing. $\endgroup$ – Mohammad Al-Turkistany Dec 27 '14 at 11:55
  • $\begingroup$ I was wondering a similar question but I see you have posted it! $\endgroup$ – TanMath Jan 1 '15 at 0:21
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The main hypothesis is that all starts from RNA. "The RNA world". There was no DNA and no proteins. Both function was performed by RNA. Now there are no living organism that carrying information in RNA (only viruses...), but there is "enzymes" from RNA - ribozymes.
The evolution to DNA was later, according to this hypothesis.
There is really good article in wiki.
http://en.wikipedia.org/wiki/RNA_world_hypothesis
or if you want something more look here
http://www.ncbi.nlm.nih.gov/books/NBK26876/

Summary

From our knowledge of present-day organisms and the molecules they contain, it seems likely that the development of the directly autocatalytic mechanisms fundamental to living systems began with the evolution of families of molecules that could catalyze their own replication. With time, a family of cooperating RNA catalysts probably developed the ability to direct synthesis of polypeptides. DNA is likely to have been a late addition: as the accumulation of additional protein catalysts allowed more efficient and complex cells to evolve, the DNA double helix replaced RNA as a more stable molecule for storing the increased amounts of genetic information required by such cells.

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    $\begingroup$ It's important to note that the RNA world is a hypothesis, not a theory. Nobody knows how life arose. $\endgroup$ – canadianer Dec 29 '14 at 12:33

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