The Three Domains Flashcards
All 6 cards in this deck
Who proposed the three domains classification, and what evidence was it based on?
Carl Woese; genetic analysis, especially comparing ribosomal RNA sequences of different organisms.
Name the three domains.
Archaea, Bacteria and Eukarya.
Why did genetic analysis lead to the five kingdoms being replaced by three domains?
Sequencing showed that the prokaryotes are really two very different groups (Archaea and Bacteria), differing in their genes, rRNA and cell chemistry, so they cannot be one kingdom.
Which organisms are in the domain Eukarya?
All organisms whose cells contain a nucleus — protists, fungi, plants and animals.
How do scientists use gene sequencing to work out how closely related two species are?
e.g. a human and a chimpanzee
- Sequence the same gene (or DNA/RNA) from both organisms.
- Compare the sequences for similarities and differences.
- The more similar the sequences, the more closely related the species and the more recent their common ancestor — human and chimp sequences are very similar.
True or false? Bacteria and Archaea belong to the same domain because both are prokaryotes.
False. Genetic analysis showed they are so different in their genes and cell chemistry that they are placed in two separate domains.