Any evidence that some organisms use bases other than A T C & G?

In summary: Earth, if it existed.In summary, the conversation revolves around the evolution of life and whether there are any forms of life that use DNA with different bases than the commonly known A, T, C, and G. The possibility of new base pairs evolving in the future is also discussed, with some evidence provided through the engineering of new base pairs in a laboratory setting. The conversation also touches on alternative codon usage in some organisms and the potential for finding evidence of alternative DNA codes in the history of life.
  • #1
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Yet another question about the evolution of life, likely in the Archaen or Proterozoic eons.

As I understand it, the genomes of all life - archaea, bacteria, eukaryotes - is based on DNA, even that of eukaryote organelles, such as plastids and mitochondria. Are there any counter-examples, in forms of life with us today (i.e. not fossils)? Viruses excluded.

Is the DNA of all forms of life based on only A, T, C, and G? Or are there some other bases, used by some weird archaea, say?

If so, details please!
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  • #3
I actually have an addition to that question. Would it ever be possible for new base pairs to evolve?
  • #5
Monique said:
U (urasil) replaces thymidine in RNA, but this doesn't answer your question. I'm not sure about a genetic code based on a divergent system, but on a higher level there is: some organisms have alternative codon usage (

This article might be of interest to you:
Thanks Monique.

I knew about U in RNA, and that, at a higher level, codon usage does not follow a single, universal, scheme.

I'm interested in the fact that, in 3+billion years of evolution, just one basic DNA code (ATCG) seems to be used. It would seem exceedingly unlikely that, had there been alternatives in the history of life*, we would be able to find any evidence of them.

On the other hand, with 'synthetic life' almost within reach, it may be possible - several decades or more from now - to determine if any such alternatives could have been, or could be!, the basis for life on an Earth-like planet.

* not counting pre-DNA life

Related to Any evidence that some organisms use bases other than A T C & G?

1. What are the other bases that some organisms use besides A, T, C, and G?

Some organisms use bases such as uracil (U) and thymine (T) in place of adenine (A) and guanine (G) in their genetic material. Additionally, some organisms may use other uncommon bases like 5-methylcytosine (m5C) or 5-hydroxymethylcytosine (hm5C).

2. Why do some organisms use different bases in their genetic material?

The use of different bases allows for a wider variety of genetic information and can provide advantages to an organism, such as increased resistance to environmental stresses.

3. How do scientists study and identify these alternative bases in organisms?

Scientists can use techniques like genome sequencing and mass spectrometry to study and identify these alternative bases in organisms.

4. Are these alternative bases found in all organisms?

No, not all organisms use alternative bases in their genetic material. They are more commonly found in unicellular organisms and viruses, but can also be found in some plants and animals.

5. Are there any potential applications for these alternative bases in biotechnology or medicine?

Yes, the discovery and study of alternative bases has potential applications in biotechnology and medicine. For example, the use of modified bases in gene therapy can improve treatment of genetic diseases by targeting specific DNA sequences with higher accuracy.

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