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Unformatted text preview: ristics.
The key to numerical taxonomy is that no one trait
(e.g., ability to ferment glucose) is elevated in
importance above any other trait (e.g., Gram
Instead, all traits are weighted equally.
Classification in numerical taxonomy is expressed
in terms of a Similarity Coefficient found between
two compared strains. It is equal to:
[# pos both strains]/[# pos one or both strains]
by “pos” I mean that the characteristic is
present, e.g., ferments glucose or has pili, etc.
Greater similarity coefficient, closer relatedness is
inferred. Greater than ~70% and inference is that
two compared bacteria are of the same species. dsDNA is
based on UV
melting temps. DNA-DNA Hybridization Helix has higher
greater fraction GC vs. A-T pairing. Higher melting
greater G-C content 5 Similarity is in terms of
between the two compared
organisms. 16S rRNA Sequence Comparison DNA-DNA Hybridization 16S rRNA Link to Next Presentation 6 DNA-DNA Hybridization 10...
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- Spring '11