How rRNA Reshaped Life's Domains

Ribosomal RNA, or rRNA, changed how scientists classify life. Sequence analysis showed three major groups of cells: eukaryotes, bacteria, and archaea. In 1978, Carl R. Woese proposed domains as a taxonomic level above kingdoms to separate these groups.

Woese also showed that archaea and bacteria ...

Based on differences in the nucleotide sequences of ribosomal RNA, all cellular life can be classified into three distinct domains — Bacteria, Archaea, and Eukarya.

These three domains originated from a common ancestor approximately 3.5 billion years ago, with significant horizontal gene transfer.

The eukaryotic cells appeared later,...