The 2015 Nobel Prize in chemistry recognizes work that "has provided fundamental knowledge of how a living cell functions." Specifically, how cells repair DNA.
And the winners are:
Tomas Lindahl discovered base excision repair, which constantly counteracts DNA collapse.
Aziz Sancar mapped nucleotide excision repair, which is what cells use to repair UV damage to DNA.
Paul Modrich demonstrated how mismatch repair drastically reduces error frequency during DNA replication.
Among other things, their work is being used to develop new cancer treatments.