Intron

Definition

An intron is a non-coding region within a gene that is removed from the mature RNA molecule during the process of RNA splicing. Introns are present in the primary transcript of a gene, known as the pre-mRNA, but are ultimately excluded from the final, functional mRNA molecule that is translated into a protein.

5 Must Know Facts For Your Next Test

1. Introns are found in the genes of most eukaryotic organisms, including plants, animals, and fungi, but are generally absent in prokaryotic organisms like bacteria.
2. The presence of introns allows for the possibility of alternative splicing, where different combinations of exons can be joined to produce multiple mRNA isoforms from a single gene.
3. Introns can play a role in gene regulation by influencing the efficiency of transcription, mRNA stability, and translation.
4. The removal of introns during RNA splicing is catalyzed by a large, complex molecular machine called the spliceosome, which recognizes specific sequences at the intron-exon boundaries.
5. Mutations in the sequences at the intron-exon boundaries can disrupt the proper splicing of the pre-mRNA, leading to the inclusion of incorrect exons or the retention of introns in the final mRNA molecule.

Review Questions

• Explain the role of introns in the process of transcription and the production of mature mRNA.
  • Introns are non-coding regions within a gene that are present in the primary transcript, known as the pre-mRNA. During the process of RNA splicing, the spliceosome recognizes and removes the introns, leaving only the coding exons to be joined together to form the mature, functional mRNA molecule. This removal of introns is a crucial step in the production of the final mRNA that can be translated into a protein.
• Describe how the presence of introns in a gene can contribute to the diversity of proteins produced by a single gene through the process of alternative splicing.
  • The presence of introns in a gene allows for the possibility of alternative splicing, where different combinations of exons can be joined together to produce multiple mRNA isoforms from a single gene. This process enables a single gene to encode for multiple, structurally and functionally distinct protein products, thereby increasing the diversity of the proteome and the range of biological functions that can be carried out by the gene.
• Analyze the potential impact of mutations in the intron-exon boundary sequences on the proper splicing of the pre-mRNA and the resulting consequences for the final mRNA and protein products.
  • Mutations in the sequences at the intron-exon boundaries can disrupt the recognition and proper splicing of the pre-mRNA by the spliceosome. This can lead to the inclusion of incorrect exons or the retention of introns in the final mRNA molecule. Such splicing errors can result in the production of mRNA transcripts that encode for altered or non-functional protein products, potentially leading to genetic disorders or other deleterious effects on the organism's health and physiology.

Related terms

Exon:

Exons are the coding regions of a gene that are retained in the mature mRNA and ultimately translated into the amino acid sequence of a protein.

RNA Splicing: RNA splicing is the process of removing introns and joining the remaining exons to form the mature, functional mRNA molecule.

Pre-mRNA: Pre-mRNA is the primary transcript of a gene, which includes both the coding exons and the non-coding introns, before the process of RNA splicing occurs.