Abbreviation for expressed sequences. An exon is a DNA segment of a eukaryotic gene that carries information for the coding protein. Between the exons of a gene there are non-coding DNA sections, the so-called introns.
Exon
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Exons are the parts of a gene that contain the coding sequence and are therefore responsible for the synthesis of proteins. In genetics, a distinction is made between exons and introns. While exons carry the information that is ultimately translated into an amino acid sequence, introns are non-coding sequences that lie between the exons and are removed during RNA processing.
The process in which the mRNA (messenger RNA) is produced by a gene involves several steps:
- Transcription: The DNA is transcribed into pre-mRNA. This pre-mRNA contains both exons and introns.
- RNA processing: The pre-mRNA is edited, removing the introns and joining (or"splicing") the exons together. The result is a mature mRNA containing only the exons.
- Translation: The mature mRNA is transported into the ribosome where it is translated into an amino acid sequence to form a protein.
Exons can also occur in multiple mRNA variants, which can lead to the formation of different proteins from the same gene - a process known as alternative splicing. This contributes to the genetic diversity and adaptability of organisms.