In all living things, the development and specialisation of individual cells is controlled by regulatory systems. They have been optimised by millions of years of natural selection and are coded in the DNA genome. It is these regulatory systems that are responsible for the incredible variety of living organisms.
Interpreting the genome
The human body, for example, contains some 1014 cells. While these cells contain exactly the same DNA genome, they are all different because of the way the genome – and its 24,000 protein-encoding genes - is interpreted.
The simple model is that RNA molecules create the regulatory system which translates the information from the DNA to form the particular proteins in each individual cell. However, this cannot fully explain the vast number of cellular proteins – additional mechanisms must be involved.
Early-stage research
The University of Copenhagen is currently researching a newly identified RNA gene family – micro RNA (miRNA) – which appears to form this additional system. So far, some 500 miRNAs have been identified in the human genome and, while the investigation is still at a relatively early stage, it is clear they have a lot to tell us about the development of the world’s fantastic biological diversity.