Was Rna the First Life Form?

Geology 304

Was RNA the first life form?

Outside of the scientific community the opinion of what makes a living organism living is somewhat diverse, with some people believing that it is an active central nervous system and brain that constitutes a living organism and others believing that anything with ongoing cellular activity should be considered living. In biology, however, the term “living organism” is slightly less controversial and has come to be accepted to mean and include any species that is capable of reproducing by itself (or with another member of its species), is capable of signaling biological self sustaining systems, and has an active metabolism (Koshland, 2002 Freeman, 2008). The term by itself is important here as it excludes viruses, which require another living organism to act as a surrogate during reproduction; furthermore, viruses lack a metabolism, both of these properties combined exclude viruses from being classified as living (Wimmer et al., 2009). The question of where living organisms evolved from is an ongoing debate, however, amongst the scientific community, ribonucleic acid (RNA) based life forms are a promising starting point for life as well as the eventual evolution of present day deoxyribonucleic acid (DNA) based life forms; the theory that life started out as RNA and later gave rise to DNA based life forms is known as the RNA world hypothesis (Freeman, 2008).

In order to understand the importance that RNA may have played in the evolution of life it is important to have a basic understanding of what RNA is comprised of and how it behaves. RNAs are polymers of nucleotides, which is to say that a single RNA molecule is made up of many different nucleotides that are chemically bound together. The nucleotides are comprised of three parts: a sugar, a phosphate group, and a nitrogenous base. The sugar in RNA is ribose, which is one of RNA’s distinguishing features from DNA, which uses deoxyribose. RNA makes a promising start for...