How Do Enol Forms of Nucleobases Impact DNA Replication?

[cj20x2]

TL;DR

A few questions about the enol forms of nucleobases.

I've been reading up on how nucleobases have both keto and enol forms, and how their enol forms can lead to point mutations in DNA replication.

1. What would cause a nucleobase to switch between keto and enol forms?
2. What happens to enol forms of nucleobases in the cell, are they used, discarded or do they eventually switch to their keto form?

 

[Ygggdrasil]

The keto and enol forms of the nucleobases are in equilibrium and can rapidly interconvert between the two forms. The keto forms are favored under physiological pH and the nucleobases spend most of their time as the keto form, but they do spend a small fraction of time in their enol form.