Final answer:
Group 1 introns are removed through a process known as splicing, which is crucial for accurate protein synthesis and is performed by spliceosomes in the nucleus.
Step-by-step explanation:
The reactions involved in the removal of group 1 introns are collectively known as splicing. During this process, a guanine nucleotide cofactor assists in forming a bond with the 5' end of the intron, which allows the exon's 3'-hydroxyl group to attack the 3′ end of the intron, leading to its excision and the joining of exons. This precise and sequence-specific mechanism is crucial for the accurate synthesis of proteins, as any single nucleotide error can lead to a dysfunctional protein. The spliceosomes, which are complexes of proteins and RNA molecules, conduct the splicing of pre-mRNAs in the nucleus.