Answer to Question #53044 in Molecular Biology for Daniel HAmmond
How are self-replicating molecules, such as RNA molecules in the “RNA World” hypothesis, essential to the most popular hypotheses about the origin of life on Earth?
One of the most popular hypothesis about the origin of life on Earth is the process of appearance of the self-replicative molecules of RNA. Scientists suggest that RNA was first molecule that could replicate itself and regulate synthesis of other bioorganic molecules (DNA and proteins). It is known that RNA really has such properties. DNA monomers (deoxynucleotides) could interact with RNA molecules in complementary way (A-U, G-C). In such way RNA molecules increased the entropy of deoxynucleotides but increased enthalpy due hydrogen interactions. After formation of phosphodiester bonds between the nucleotides DNA molecule was formed. In the case of proteins RNA molecules organised amino acids in some order that was energetically beneficial. After formation of peptide bonds protein molecule was formed. RNA molecules with catalytic activities are found and are called ribozymes. For example, splicing (processing of mRNA) is a result of ribozymes activity. Protein synthesis is also a result of ribozyme activity of ribosome RNA (ribosome proteins play regulatory role). So, after formation of DNA (more stable information store of genetic information than RNA) and proteins (more flexible and functionally diverse molecules than RNA) life could appeared and cell-like structure were formed. Self-replicating RNA organised other monomers and catalyzed the most important synthetic reactions in the way of polymer formation.