A related but distinct nucleic acid
RNA has a ribose–phosphate backbone and commonly uses A, U, C and G, with uracil represented by U. It is usually single-stranded but can fold through local base pairing. Single-stranded therefore does not mean shapeless; structure affects binding partners and the activities a molecule can perform.
References: [1]
Messenger RNA and transcription
Transcription produces RNA from a DNA template, and messenger RNA carries protein-coding information into translation. Eukaryotic transcripts commonly undergo processing before functioning as mature messages. Transcription and processing are regulated; cells do not simply copy every part of their DNA equally and manufacture every possible protein without control.
Ribosomal and transfer RNA
Ribosomal RNA is a major functional component of ribosomes. Transfer RNA connects codons in a message with corresponding amino acids. These RNAs divide tasks within one process: translation requires a template together with recognition and assembly machinery. Describing RNA only as a courier overlooks its functional roles.
Regulation and viral RNA
Other RNAs regulate gene expression or RNA processing without serving as protein templates. Some viruses store genetic information in RNA rather than DNA, requiring separate accounts of replication. RNA research spans cell biology, genetics and virology; the role of a particular molecule depends on its molecular and biological setting.