Q.The process of splicing in eukaryotes represents the dominance of the : (A) DNA world (B) RNA world (C) Protein world (D) Lipid world
The process of splicing in eukaryotes reveals that RNA itself can act as an enzyme, providing strong evidence for the "RNA world" hypothesis — the idea that RNA was the first self-replicating molecule in early life.
To understand why splicing points to the RNA world, we need to step back and think about what splicing actually is. In eukaryotic cells, genes are split into coding sequences (exons) and non-coding sequences (introns). After transcription, the initial RNA transcript — called pre-mRNA — contains both exons and introns. Splicing is the process that removes the introns and joins the exons together to form a mature mRNA that can be translated into protein.
Now here is the remarkable part. For many years, biologists assumed that all biological reactions were catalysed by proteins (enzymes). But in the 1980s, Thomas Cech and Sidney Altman independently discovered that certain RNA molecules can act as catalysts. These are called ribozymes — RNA enzymes. The splicing of some introns, particularly self-splicing introns (like Group I introns), is carried out entirely by the RNA itself, without any protein help. The intron folds into a specific three-dimensional shape that brings the ends together and catalyses the cutting and rejoining reactions.
The discovery of self-splicing RNA was a landmark because it shattered the dogma that only proteins could be enzymes. It showed that RNA can both store genetic information (like DNA) and catalyse chemical reactions (like proteins).
This dual ability — information storage and catalysis — is the core of the RNA world hypothesis. The idea is that before DNA and proteins evolved, early life may have used RNA as the primary molecule for both heredity and metabolism. DNA is chemically more stable and better for long-term storage, while proteins are more versatile catalysts. But RNA could have been the transitional molecule that made the leap from simple chemistry to the first living systems.
Splicing is a direct living example of this ancient capability. When we see an intron being removed by an RNA catalyst, we are watching a molecular fossil — a relic of a time when RNA ruled the biological world. The fact that splicing occurs in eukaryotes (and not in prokaryotes) also hints that the spliceosome — the complex that carries out splicing in our cells — may have evolved from self-splicing introns.
The spliceosome itself is a large complex of proteins and small nuclear RNAs (snRNAs). Some of those snRNAs actually perform the catalytic steps, so even in modern eukaryotes, the core of splicing remains an RNA-driven process.
So when the question asks what splicing represents, it is not about which molecule is more abundant or important today. It is about what the mechanism of splicing tells us about the history of life. The fact that RNA can catalyse its own processing is a powerful argument that RNA, not DNA or protein, was the first dominant biological molecule.
In short, the process of splicing in eukaryotes represents the dominance of the RNA world — because it demonstrates that RNA can act as a catalyst (ribozyme), supporting the idea that RNA was the first self-replicating and catalytic molecule in early evolution.
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