RNA
A generally single-stranded nucleic acid that carries out the expression of genetic information.
Unit
Dimensionless
In depth
Ribonucleic acid uses ribose and substitutes uracil for thymine. Being single-stranded, it folds into complex shapes, which allows some RNA molecules to act as catalysts. The main types transcribe, transport and translate the genetic message.
Examples in the real world
Messenger RNA carrying the gene copy; transfer RNA delivering amino acids; ribosomal RNA catalysing peptide bonds.