Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes. RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life. The main function of RNA is to carry information of amino acid sequences from the genes to where proteins are assembled on ribosomes in the cytoplasm. This is done by messenger RNA (mRNA). A single strand of DNA is the blueprint for the mRNA which is transcribed from that DNA strand.