Introns

Introns are non-coding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein. The sections of DNA or RNA that remain are known as exons.

Overview

Introns were first discovered in 1977 by Richard J. Roberts and Phillip A. Sharp, who were awarded the 1993 Nobel Prize in Physiology or Medicine for their discovery. Introns are found in the genes of most organisms and many viruses. They can be located in a wide range of genes, including those that generate proteins, ribosomal RNA (rRNA), and transfer RNA (tRNA).

Function

The function of introns in DNA is still not completely understood. While they do not code for protein sequences, they may influence the expression of other genes. Some introns contain sequences that regulate gene expression, while others may serve as sites for alternative splicing, allowing for the production of multiple proteins from a single gene.

Splicing

Introns are removed from the pre-mRNA during the process of RNA splicing. This process is usually carried out by a complex of proteins and small nuclear RNA molecules known as the spliceosome. In some cases, introns can self-splice, removing themselves from the RNA molecule without the need for additional proteins or RNA.

Evolution

The presence of introns in various groups of organisms is used as evidence for the theory of Eukaryotic evolution. The most common explanation for their existence is that they are remnants of ancient genes that have been incorporated into new genes through the process of gene duplication and mutation.

See also

• Exon
• Gene expression
• RNA splicing
• Spliceosome

References

Introns Resources
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