Introduction:

The process of splicing plays a crucial role in the dominance of the RNA-world hypothesis. This hypothesis suggests that early life on Earth was based on RNA molecules, which are capable of both storing genetic information and catalyzing chemical reactions. Splicing, a process involved in the maturation of RNA molecules, provides evidence supporting the RNA-world hypothesis.

Explanation:

1. RNA Splicing:
RNA splicing is a process where the non-coding regions, called introns, are removed from the pre-messenger RNA (pre-mRNA) molecule, and the remaining coding regions, called exons, are joined together to form the mature mRNA molecule. This process is crucial for the expression of genes and the production of functional proteins.

2. Introns and Exons:
Introns are segments of DNA that do not code for proteins, while exons are the segments that contain the protein-coding regions. During splicing, introns are removed, and exons are joined together. This process allows for the generation of a diverse range of proteins from a limited number of genes through alternative splicing.

3. Alternative Splicing:
Alternative splicing is a mechanism that generates multiple protein isoforms from a single gene by selectively including or excluding certain exons during splicing. This process greatly increases the coding potential of the genome and allows for the production of proteins with different functions or tissue-specific expression patterns.

4. RNA World Hypothesis:
The RNA-world hypothesis suggests that RNA molecules played a central role in the early evolution of life on Earth. It proposes that RNA molecules not only stored genetic information but also had catalytic properties, acting as enzymes. This hypothesis is supported by the discovery of ribozymes, RNA molecules that can catalyze specific biochemical reactions.

5. Splicing and RNA World:
The process of splicing provides evidence for the RNA-world hypothesis. Splicing is a complex process that requires the presence of small nuclear ribonucleoproteins (snRNPs) and spliceosomes, which are composed of RNA and proteins. The catalytic activity of these RNA molecules in the splicing process supports the idea that RNA molecules could have functioned as enzymes in the early stages of life.

Conclusion:
In conclusion, the process of splicing represents the dominance of the RNA-world hypothesis by demonstrating the catalytic capabilities of RNA molecules. Splicing allows for the generation of diverse protein isoforms through alternative splicing, increasing the coding potential of the genome. The presence of catalytic RNA molecules in the splicing process provides evidence for the RNA-world hypothesis, suggesting that RNA played a central role in the early evolution of life on Earth.