Final answer:
True, snRNAs such as U1 and U2 are crucial for spliceosome formation, which is responsible for pre-mRNA splicing, removing introns and joining exons to generate mature mRNA.
Step-by-step explanation:
True, small nuclear RNAs (snRNAs) such as U1 and U2 are essential for the formation of a functional spliceosome. These snRNAs combine with proteins to form small nuclear ribonucleoproteins (snRNPs), which are critical components of spliceosomes. The spliceosome is a large complex that is responsible for pre-mRNA splicing, which involves the precise removal of non-coding sequences called introns from a primary RNA transcript. As part of the spliceosome, snRNAs have several functions including recognizing splice sites at the 5' and 3' ends of introns, and catalyzing the splicing reactions that remove introns and ligate exons to produce mature, translatable messenger RNA (mRNA).