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intron

Figure 1. DNA initially transcribed to immature messenger RNA (mRNA) consists of coding sequences (exons) and noncoding sequences (introns).

intron

Figure 2. Introns have been spliced out of the immature mRNA to form mature mRNA, leaving only the exons to ultimately encode the amino acid product.

Illustrations adapted from Nussbaum RL, McInnes RR, Willard HF, eds: Thompson & Thompson Genetics in Medicine, 6 ed. The human genome: structure and function of genes and chromosomes, Fig 3-6, p 20. Copyright 2001, with permission from Elsevier.

Revised: 4-22-16

Related terms: coding region; exon; intronic; splicing

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