Practice question

Carl Woese revolutionized biological classification in 1977 and 1990 by constructing phylogenetic trees using small subunit ribosomal RNA and ribosomal protein sequences, choosing molecules present in all cells and evolving slowly with minimal horizontal transfer. Comparative oligonucleotide cataloguing and later sequencing revealed that sequence signatures distinguished Archaea from Bacteria and Eukarya robustly. His three-domain system based on molecular chronometers superseded five-kingdom morphological scheme, emphasizing genotype over phenotype. Subsequent genomic analyses of replication, transcription, and translation machinery reinforced domain separation rooted in ribosomal evolution.