heterogeneous nuclear ribonucleic acid

het·er·o·ge·ne·ous nu·cle·ar ri·bo·nu·cle·ic ac·id

(hnRNA) (hetĕr-ō-jēnē-ŭs nūklē-ăr rībō-nū-klēik asid) Mixture of RNA, of high molecular weight, which never leaves the nucleus; quick turnover of mRNA containing both introns and exons of genes.