Arsenate: Difference between revisions

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* In strongly [[acid]]ic conditions it exists as [[arsenic acid]], H<sub>3</sub>AsO<sub>4</sub>;
* in weakly acidic conditions it exists as '''dihydrogen arsenate''' ion, H<sub>2</sub>AsO<sub>4</sub><sup>&minus;</sup>;
* in weakly basic conditions it exists as '''hydrogen arsenate''' ion HAsO<sub>4</sub><sup>2&minus;</sup>;
* and finally, in strongly basic conditions, it exists as the arsenate ion AsO<sub>4</sub><sup>3&minus;</sup>.
In 2008, bacteria were discovered that employ a version of [[photosynthesis]] with arsenites as [[electron donor]]s, producing arsenates (just like ordinary photosynthesis uses water as electron donor, producing molecular oxygen). The researchers conjectured that historically these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive.<ref>[ Arsenic-loving bacteria rewrite photosynthesis rules], Chemistry World, 15 August 2008</ref>
In 2010, a team at [[NASA]]'s [[NASA Astrobiology Institute|Astrobiology Institute]] cultured samples of arsenic-resistant [[GFAJ-1]] bacteria from [[Mono Lake]], using a medium high in arsenate and low in phosphate concentration. The findings suggest that the bacteria may partially incorporate arsenate in place of phosphate in some biomolecules, including DNA,<ref>[ A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus]. Wolfe-Simon F, Blum JS, Kulp TR, Gordon GW, Hoeft SE, Pett-Rdige J, Stolz JF, Webb SM, Weber PK, Davies PCW, Anbar AD, Oremland RS. ''Science'' Express. 02 December 2010.</ref><ref>[ NASA Finds New Arsenic-Based Life Form in California], ''Wired Science'', Dec 2 2010</ref>, but the validity of this claim is still being debated.<ref>[ Novel expansion of living chemistry or just a serious mistake?]. Silver S, Phung LT. ''FEMS Microbiology Letters''. 12 January 2011. 315: 79-80.</ref>
==See also==