"Sound evidence points to the theory that RNA is the first living molecule. RNA is good at copying itself and it carries a lot of information in its structure. In today's cell, RNA acts as a sort of office messenger. If DNA is the master architect, RNA is like an assistant who takes a blueprint from DNA and plugs it into cellular machines. (These machines, called ribosomes, are actually made up of RNA as well.) These ribosomes read the blueprint like a set of instructions that tell which amino acids to hook together."