This new featurette of The Amazing Spider-Man talks about Dr Curt Connors (Rhys IFans) aka The Lizard:

Dr Curtis Connors is a genetics expert who’s been working and doing various experiments for Oscorp Industries. Before that, he was a gifted surgeon who enlisted in the U.S. Army and was sent off to war. He performed emergency battlefield surgery on wounded GIs, but his right arm was injured in a blast and had to be amputated. Using reptilian DNA he tried to regrow his lost limb. But he ten transformed into the evil Lizard.
:)