Quote of the Week
(February 17, 2025)

The discovery of RNA splicing in the late 1970s was one of the transforming moments in the history of molecular biology. To put it in informal terms: the cleanly autocratic mastery of DNA gave way to massive presumption by various scruffy elements of the cellular “rabble”. The idea had originally been that a molecule of messenger RNA (mRNA) was produced as a direct image of the “instructions” in a protein-coding gene and was then exported from the cell nucleus to the cytoplasm. There it yielded passively to translation, a process whereby a protein was supposedly produced according to the exact specifications of the “genetic code” previously copied from DNA into the mRNA.

Our growing knowledge of RNA splicing has, together with many other developments in molecular biology, exploded just about every aspect of this picture. We now know that, via an elaborately orchestrated improvisational drama, many so-called epigenetic elements in the cell (Chapters 7, “Epigenetics: A Brief Introduction”, and 14, “How Our Genes Come to Expression”) converge to decide what use will be made of any particular gene.

In particular, the cell has innumerable ways to obtain and sculpt its proteins. RNA splicing is just one of these — a massive reconfiguration process whereby a cell decides which portions of an initially produced (precursor) RNA to cast aside for other uses, and which ones to “splice” together into a mature mRNA. As we have come to expect by now, these choices are strongly context-dependent, with different protein variants being produced in different kinds of cell or tissue, or under different cellular conditions.

(from Chapter 8, “The Mystery of an Unexpected Coherence”, in Organisms and Their Evolution — Agency and Meaning in the Drama of Life)

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