In prokaryotes, the DNA undergoes transcription and forms the mRNA. Whereas in eukaryotes the DNA undergoes transcription to form hn-RNA (heterogeneous RNA), which consists of coding (exons) and non-coding sequences (introns). Through the process of splicing the coding and noncoding sequences are separated. The exons are joined together using ligase enzymes. Now the resulting strand consists of only the coding sequence. The strand thus formed is called mRNA. Therefore, in eukaryotes, the entire base sequence of a gene does not appear in mature RNA due to loss of introns during the process of splicing.