Self-splicing RNA intron, molecular model. Splicing is the process where a non-coding fragment (intron) of a strand of nucleic acid (DNA, deoxyribonucleic acid; or RNA, ribonucleic acid) is removed. The two sections either side of the intron are called extrons, and are joined together to reform the strand. This splicing is self-organised, and is taking place on an RNA strand. The intron is known as a group I catalytic intron, a self-splicing ribozyme. Also present is small nuclear ribonucleoprotein A (snRNP-A).