what is an intron

An intron is a nucleotide sequence within a gene that is not expressed or operative in the final RNA product. In other words, introns are regions that reside within a gene but do not remain in the final mature mRNA molecule following transcription of that gene and do not code for amino acids that make up the protein encoded by that gene. Most protein-coding genes in the human genome consist of exons and introns. Exons are the coding sequences that code for the amino acid sequence of the protein. When genes are transcribed, both exons and introns are included in the initial messenger RNA products. However, introns are removed during the process called splicing so that only exons are included in the mature mRNA and used to dictate what proteins are produced. Introns may contain sequences that regulate how genes are expressed or transcribed and how mRNA is processed.