The single stranded polymeric nucleic acid, which serves as a template for encoding proteins is called RNA (ribonucleic acid). The process that synthesizes RNA is called transcription or gene expression, which is usually done by the aid of the enzyme called RNA-polymerase.
The transcription of genes, give four types of RNA, namely
• mRNA (messenger ribonucleic acid)
• tRNA (transfer ribonucleic acid)
• rRNA (ribosomal ribonucleic acid)
• snRNA (small nuclear ribonucleic acid)
The mRNA is code for different types of proteins, whereas the tRNA and rRNA used for translation of mRNA. The tRNA transfer amino acids to the site of translation (protein synthesis). The rRNA is a part of ribosomes, which reads the mRNA and synthesizes proteins. The snRNA is a part of spliceosome complex, which splices the introns form an hnRNA (heteronuclear RNA) and gives a functional RNA called mRNA.