文档介绍：Chapter 12 Microbial Evolution and Systematics
Ribosomal RNAs as Evolutionary Chronometers:
The 16S rRNA or 18S rRNA Technique
Ribosomal RNAs as Evolutionary Chronometers
Reasons:
Ancient molecules
Functionally constant
Universally distributed
Moderately well conserved in sequence across broad ic distances
The 16S rRNA or 18S rRNA Technique
The 16S rRNA or 18S rRNA Technique
In Prokaryotes:
5S rRNA is too small, contains limited info
23S rRNA is too large, too difficult to manage
16S rRNA has the right size for studies
In Eukaryotes:
18S rRNA is used for ic measurements
The 16S rRNA or
18S rRNA Technique
The 16S rRNA or 18S rRNA Technique
Ribosomal Database Project (RDP):
/pare your sequences with the database to find out anisms you identify
ic Trees from DNA Sequences
Distance-Matrix Method for generating the trees
Evolutionary Distance (ED)
pare the sequence differences and build the ic tree based on corrected ED
ic Trees from DNA Sequences
Signature Sequences: unique to certain group anisms
Applications: ic Probe