Ribosomal IDPs - more mutations with less evolution over billions of years


Ribosomal RNA (rRNA) is one of the most conserved molecules in the cell. This means that its function has changed very little over billions of years of evolution. There are several reasons for this, one of which is the presence of intrinsically disordered regions (IDRs) in rRNA.

IDRs are regions of RNA that do not have a fixed structure. They are characterized by a high degree of flexibility and variation in their secondary structure. This flexibility allows rRNA to adapt to different environments and interact with different proteins, which is essential for its function in protein synthesis.

IDPs (Intrinsically Disordered Proteins) do not act according to the mutation model of neo-Darwinism. Neo-Darwinism proposes that mutations are the driving force of evolution, and that mutations that are beneficial to an organism will be passed on to future generations. However, IDPs are able to tolerate more mutations without change, which suggests that mutations do not drive evolution in IDPs.

If rRNA were to have a more fixed structure, it would be less adaptable and less likely to be able to function in different organisms. This is why IDRs are thought to be one of the factors that contribute to the evolutionary conservation of rRNA. NeoDarwinism was developed on the structured protein model. We now know most proteins are IDPs, which sidesteps this model.

In addition to IDRs, there are other factors that contribute to the evolutionary conservation of rRNA. These include the essential role that rRNA plays in protein synthesis, the high fidelity of RNA replication.

The essential role of rRNA in protein synthesis means that any changes to its sequence could have a negative impact on the ability of the cell to synthesize proteins. 

The high fidelity of RNA replication also helps to ensure that the sequence of rRNA is conserved. RNA polymerase, the enzyme that copies DNA into RNA, is very accurate, and so it makes very few mistakes. This minimizes the chances of mutations occurring in rRNA.

Organisms with rRNA sequences that are more likely to be functional will be more likely to passing on their genes to the next generation.

As a result of all of these factors, rRNA has remained remarkably conserved over billions of years of NonDarwinian evolution. This is essential for the survival of all living organisms, as rRNA is essential for protein synthesis.


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