What is a spliceosome primarily involved in?

The spliceosome plays a critical role in the processing of pre-mRNA in eukaryotic cells, specifically in the removal of introns and the joining of exons to form a mature mRNA transcript. Introns, which are non-coding sequences, must be excised from the pre-mRNA before it can be translated into a protein. The spliceosome is composed of small nuclear RNAs (snRNAs) and protein factors, working together to recognize specific sequences at the intron-exon boundaries, facilitating the precise cutting and rejoining of the mRNA. This process is essential because it ensures that the coding sequences (exons) are correctly joined together, enabling the ribosome to translate the mRNA into an appropriate protein.

The other options relate to different biological processes: Translation involves converting mRNA into protein, DNA replication is about duplicating DNA strands before cell division, and DNA repair encompasses mechanisms that maintain the integrity of the genetic material. Each of these processes is distinct from the function of a spliceosome, which is specifically dedicated to RNA splicing.