RNA chains play fundamentally important roles within the cell, including genetic information transfer (mRNA), components of the translation machinery (rRNA in ribosomes and tRNAs) and as regulatory small RNAs.
The tertiary structure of RNA is determined by interactions that maximise base pairing. Despite instability and isolation problems, the tertiary structures of several major cellular RNAs are known.
Transfer RNA structure is highly specialised for its role in translation.
Hairpin RNAs called MiRNAs are present in many eukaryotes and are processed by a cellular ribonuclease called dicer to yield short 21–25-nucleotide RNAs, which exert effects upon mRNA stability, translation and DNA.
A class of strand-cleaving ribozyme RNAs exist as intron-splicing molecules. They have been exploited as therapeutic and experimental tools to target mRNAs in cells.
Short oligonucleotide chains can act as antisense regulators of mRNA levels.
The potential for single-stranded nucleic acids to adopt many different structural conformations has been exploited to develop aptamers that demonstrate selective high-affinity binding to target molecules.