Sequence of which of the following is used to know the phylogeny ?
- DNA
- r-RNA
- m-RNA
- t-RNA
Answer
(2) r-RNA
Solution
Phylogeny is the evolutionary history (relationship) of organisms.
∵ Ribosomal RNA is present in all living cells, performs the same function everywhere and its sequence changes very slowly (highly conserved).
⇒ Comparison of small-subunit r-RNA (16S / 18S r-RNA) sequences shows how closely organisms are related; this molecular evidence (Carl Woese) led to the separation of Archaebacteria.
∴ r-RNA sequences are used to know the phylogeny.
Answer: (2)