Talk:Last universal common ancestor/Archives/2012/November

Exceptions to the rules

My 2 cents: To my knowledge, yes, the D-epimer of glucose is used ubiquitously, but not unanimously, by life on Earth. I'm just mentioning this not to disprove the validity of the theory but for the article to carry a certain discipline that does not take liberties with scientific fact. Similarly, while L-amino acids are used almost everywhere, I believe that there are examples of D-amino acids out there as well. As with ATP: even humans use GTP, etc and other forms. It's not so much the A in ATP that gives energy --it's the energy stored in the pyrophospate bond that allows ATP --> ADP --> AMP to release energy.

Example: Burkholderia caryophylli uses L-glucose Cone snails use D-amino acids Google it if you want references.

I'm just trying to say that we can't make universal claims when they are not in fact true. You can choose to glaze over these 'details', but ultimately the absolute statements contained in the article are false. — Preceding unsigned comment added by 190.97.118.2 (talk) 03:55, 24 July 2012 (UTC)

Please click "edit" and go for it (add a source or two in brackets and someone will format them properly). Johnuniq (talk) 07:01, 24 July 2012 (UTC)

No, the general features of LUCA in the article are correct, but afterwards the descendants diversified their metabolisms and some rare exceptions appeared. For instance, conus snails use D-amino acids (a post-translational modification) but this is not an original (primitive) feature. LUCA probably used L-amino acids. The same for the other examples.--Miguelferig (talk) 21:18, 2 November 2012 (UTC)