RNA, or ribonucleic acid, is a biological macromolecule made of nucleotides used in cells to convey genetic information to protein. RNA also plays a role in catalyzing certain biological reactions as well as carrying genetic material in some viruses.
RNA, like dna, is a heteropolymer of mononucleotides connected by phosphodiester bonds. However, RNA mononucleotides have ribose instead of deoxyribose and Uracil instead of Thymine. RNAs, unlike DNA form a variety of secondary and tertiary structures. Cellular RNAs are predominantly single stranded but can form intramolecular hydrogen bonds in DNA-like and other patterns such as Hoogstein base pairing.
Three main classes of RNA incude:
- messenger RNA (mrna): serve as a template for protein synthesis
- non-coding RNA (ncRNA): serve diverse functions ranging from being a part of core-protein synthesis machinery to gene regulation
- genomic RNA: serve as genetic material of certain viruses
ncRNA is a diverse class including:
- Ribosomal RNAs (rrna): structural and catalytic components of protein synthesis
- Transfer RNA (trna): carry charged amino-acids for protein synthesis]
- Long-noncoding RNA: diverse functions (yet to be characterized)
- MicroRNA (miRNA): small regulatory RNA which post transcriptionally regulate gene expression
- Small interfering RNA (siRNA) :small RNAs which silence target mRNA/lncRNA
- Piwi-associated RNA (piRNA): small RNAs that silence transposons
