14. We have recently learned about microbes that can use Arsenic in place of Pho

Question

14. We have recently learned about microbes that can use Arsenic in place of Phosphorus in biomolecules including DNA, proteins and ribosomes. Much of the media hype surrounding this finding has proposed that this is a “new life form!” How could you determine whether in fact this is a new form of life? What gene(s) would you use to build your tree? Is it likely that this represents new life?

15. What do you think is most likely? A tree of life? A ring of life? A web of life? How does horizontal gene transfer influence your opinion?

Explanation / Answer

Q14. A new life form would have novel metabolism and physiology which can be revealed by high throughput genomics and proteomics. If it shows signs of processes which have not been found in any other life form and has an alternate pathway for metabolism, then we may conclude that it might have something to do with a novel life form.

I would use those genes which are playing a part in metabolism wherever Phosphorus was used. This will help us determine how arsenic has taken over phosphorus in the course of evolution.

This may represent a new life form provided it shows enough evidence of extraterrestrial origin in different respects before something can be concretely concluded about its origin.

Q15. It could be a tree of life from which different life forms could emanate which would share same features as its predecessor. A horizontal gene transfer could result in that but for that the parent life form transferring the gene must be found in the same nieche or elsewhere on this earth. Its existence would prove that such a gene transfer may have actually taken place.

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