Ribonucleic acid (RNA) differs from DNA in having uracil in place of thymine and most RNA are single stranded. There are three types of RNA: messenger RNA (m-RNA), transfer RNA(t-RNA) and ribosomal RNA(r-RNA). m-RNA associates with ribosomes of protein synthesis. While the RNA is helical and transfers specific amino acids from cytoplasm to the site of protein synthesis. rRNA are part of ribosomes.