The RNA world hypothesis proposes that self–replicating ribonucleic acid (RNA) molecules were precursors to
current life, which is based on deoxyribonucleic acid (DNA), RNA and proteins.
Once the organic polymers formed and became organized into protobionts (Protobionts are systems that are considered to have possibly been the precursors to prokaryotic cells. ), they needed a way to copy themselves. This is a key point in any discussion about life's origin.
Most modern organisms use a DNA–based replication system, but this is believed to have been too complex for early life forms. It is generally accepted that before DNA, there was an “RNA world”. However, it is not known whether RNA was the first genetic mechanism or how RNA monomers formed.
Modern RNA polymers provide much insight into the proposed function of RNA as the first hereditary unit. RNA has properties similar to DNA and proteins because it is a genetic molecule with enzymatic action.
RNA is the sole genetic material for some viruses, and it serves as a carrier of genetic material in many living organisms. RNA is able to polymerize by using clay or other substrates as a catalyst. RNA can self-replicate short strands (up to 40 nucleotides if zinc is present as a catalyst).