Q) Explain the benefits of the molecular classification of organisms
Main points | |
Key idea: | Basis of using molecular methods to classify organisms |
· All organisms can be classified throu this method since all known life is based on nucleic acids · Involves comparing nucleotide bases b/w organisms to determine their evolutionary relatedness · Closely related organisms share similar base sequences as compared to distantly related organisms | |
Key idea: | Adv 1: Almost limitless set of characters for analysis |
· Base sequences – each nucleotide base at each position of chrom can be considered as a character · Almost limitless no. of characters since genome of organisms consists of millions of nucleotides · Type of molecular data often used - DNA sequence of a gene that change (mutate) at a fairly constant rate + mutation that is selectively neutral | |
Key idea: | Adv 2: Molecular data is quantifiable and accessible |
· Data can be submitted or retrieved from an online database to compute the probable relatedness of two organisms in a quantitative manner | |
Key idea: | Adv 3: Molecular data is objective (unambiguous) |
· Avoids pitfalls of convergent evolution or subjective nature of distinguishing morphological struc | |
Key idea: | Adv 4: Differences in molecular data |
· Differences in mol data can be used to (i) accurately determine degree of relatedness b/w organisms with very different phenotypes (ii) classify organisms even if their phenotypes are highly similar | |
Key idea: | Adv 5: Applicable even for extinct / non-living organisms |
· Can classify organisms even if they are no longer living since DNA is highly stable so can be retrieved from living or dead cells · Once sequenced, data can be stored indefinitely (via electronic database) | |
Comments: (i) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (ii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iii) Assumption for Adv 5 - DNA is not degraded. Given the right conditions and the stability of DNA, this molecular method is especially useful for studying extinct species. (iv) I’ll modified the last point (Adv 4 & 5) slightly to make them easier to understand (hopefully !) | |
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