Intron
An intron is a non-coding sequence in a gene.
An intron is a non-coding sequence in a gene.
It is any nucleotide sequence within a gene that is removed by RNA splicing to get the final RNA product of a gene.[1][2] The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts.[3]
Sequences of coding DNA which are joined together in the final RNA after RNA splicing are exons. They code for amino acids in the final polypeptide.
Introns are in the genes of most organisms and many viruses. They can be in a wide range of genes, including those that generate proteins, ribosomal RNA (rRNA), and transfer RNA (tRNA). RNA splicing takes place after transcription and before translation.
- Introns: parts of a gene which are discarded: non-working bits.
- Exons: parts of a gene which are expressed: bits of a gene which code for amino-acid sequences in a protein.
The discovery of introns led to the Nobel Prize in Physiology or Medicine in 1993 for Phillip Sharp and Richard Roberts. The term intron was introduced by American biochemist Walter Gilbert.[4]
Biological meaning
There are many unanswered questions about introns. It is unclear whether introns serve some specific function, or whether they are selfish DNA which reproduces itself as a parasite.[5]
Recent studies of entire eukaryotic genomes have now shown that the lengths and density (introns/gene) of introns varies considerably between related species. There are four or five different kinds of intron. Some introns represent mobile genetic elements (transposons).
Alternative splicing of introns within a gene allows a variety of protein isoforms from a single gene. Thus multiple related proteins can be generated from a single gene and a single precursor mRNA transcript. The control of alternative RNA splicing is performed by complex network of signalling molecules. In humans, ~95% of genes with more than one exon are alternatively spliced.[6]
References
- ↑ Alberts, Bruce (2008). Molecular biology of the cell. New York: Garland Science. ISBN 978-0-8153-4105-5.
- ↑ Stryer, Lubert; Berg, Jeremy Mark; Tymoczko, John L. (2007). Biochemistry. San Francisco: W.H. Freeman. ISBN 978-0-7167-6766-4.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ↑ Kinniburgh, Alan; Mertz J. and Ross J. (1978). "the precursor of mouse β-globin messenger RNA contains two intervening RNA sequences". Cell. 14 (3): 681–693. doi:10.1016/0092-8674(78)90251-9. PMID 688388. S2CID 21897383.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Gilbert, Walter (1978). "Why genes in pieces". Nature. 271 (5645): 501. Bibcode:1978Natur.271..501G. doi:10.1038/271501a0. PMID 622185. S2CID 4216649.
- ↑ Orgel L.E. & Crick, F.H.C. 1980. Selfish DNA: the ultimate parasite. Nature, 284, 604-607.
- ↑ Pan, Q; Shai O, Lee LJ, Frey BJ, Blencowe BJ 2008. Deep surveying of alternative splicing complexity in the human transcriptome by high-throughput sequencing. Nature Genetics 40 (12): 1413–1415. doi:10.1038/ng.259. PMID 18978789.
Content Disclaimer
Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.
- The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
- There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
- It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
- Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
- Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.