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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 , 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 (): 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 (): structural and catalytic components of protein synthesis
  • Transfer RNA (): 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