Question

What is meant by the term self-splicing? What types of introns are self- splicing?

Short answer

Self-splicing is the process where introns, the non-coding sequences of DNA, remove themselves from the coding sequences called exons without the help of the typical splicing machinery. The two types of self-splicing introns are Group I and Group II, which use different splicing mechanisms.

Step-by-step solution

Understanding Self-splicing

Self-splicing is a process in some genes where introns, non-coding sequences of DNA, can remove themselves from between exons, the coding sequences of DNA. This is done without the aid of the usual spliceosome machinery.

Types of Self-splicing Introns

There are two main types of introns that self-splice: Group I introns and Group II introns. These groups are named based on the distinct mechanisms they use to splice themselves out of the pre-mRNA molecule.

Detailing Group I Introns

Group I introns perform self-splicing by using a guanosine molecule (G) that binds to the 5' splice site of the intron. This initiates a transesterification reaction which removes the 5' exon from the intron.

Detailing Group II Introns

Group II introns carry out self-splicing by utilizing an internally bound adenine to catalyze their removal. These introns form a lariat structure, which is a looped structure, to facilitate their removal.