RNA

In general, a cell has more RNA than DNA, mostly incorporated in ribosomes with a relatively low rate of turnover. Only a small portion of human DNA has coding potential. Almost all RNA sequences in the cytoplasm, being derived from DNA coding sequences, have functional significance, whether transcribed in coding for proteins (mRNA), in performing translation (ribosomal RNA as ribozymes, and transfer RNA), or in epigenetic mechanisms. Substantial damage to RNA induces apoptosis (cell suicide), so RNA repair mechanisms are vital to cells.

RNA differs from DNA in its general composition – ribose is the sugar moiety in the nucleotide backbone, and uracil (U) serves as a base in place of thymine (T).