A barbarous new word I have just discovered in the course of cross-checking my genetics notes. I have kept looking at the screen and repeating it to myself a few times, not quite believing it could be real. Let us proceed on the assumption that it is.

A spliceosome is an organelle inside the nucleus of a cell that is functionally a bit similar to a ribosome. It takes an mRNA strand fresh off the DNA and edits this primary transcript, cutting out the useless introns, and sewing together or splicing the remaining bits, the exons, which actually make up the working gene.

It is composed of some proteins and several molecules of a nucleic form of RNA called snRNA. It is probably guided by the fact that introns in unedited mRNA generally begin with base sequence GU and end with AG.

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