The exons are the sequences that will remain in the mature mRNA. ... Thus, the exons contain both protein-coding (translated) and non-coding (untranslated) sequences. Also note that the transcription of all mRNAs begins and ends with an exon and introns are located between exons.

Are exons coding or noncoding?

Exons are coding sections of an RNA transcript, or the DNA encoding it, that are translated into protein. Exons can be separated by intervening sections of DNA that do not code for proteins, known as introns.

Are introns non-coding?

Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein. The sections of DNA (or RNA) that code for proteins are called exons.