Life Depends on Arsenic?

As Gropper, Smitth and Groff tell it, arsenic "conjures an image of toxicity" unlike any other ultratrace mineral (1), but there are good things that come of arsenic and its story is worth discussion. Without arsenic, DNA synthesis couldn't happen. This is because arsenic is needed for normal metabolism. Specifically, the mineral is required for forming and using methyl groups to