Final answer:
Introns are found more frequently in the genes of higher eukaryotes than in those of lower eukaryotes. They may play regulatory roles or be remnants of ancient gene fusions, affecting gene expression and evolution.
Step-by-step explanation:
Introns are generally found in genes of higher eukaryotes more frequently than in the genes of lower eukaryotes. Introns, or intervening sequences, are non-coding regions within a gene that are removed during the processing of messenger RNA (mRNA). Higher eukaryotes, like humans and other mammals, have genes that very often contain one or more introns. These can be quite long, sometimes making up a significant portion of the gene.
The presence of introns may serve various functions, including regulatory roles in gene expression. However, the biological significance of having many introns or very long introns remains a matter of debate. It's worth noting that gene expression may be slowed down in genes with numerous introns, since it takes longer to transcribe these pre-mRNAs. Furthermore, introns could be remnants from the evolutionary fusion of ancient genes, with separate exons often encoding distinct protein domains or subunits.