Chapter 12 Microbial Evolution and systematics Ribosomal rnas as evolutionary chronometers: The 16s rRNA or 18S rRNA Technique
Chapter 12 Microbial Evolution and Systematics Ribosomal RNAs as Evolutionary Chronometers: The 16S rRNA or 18S rRNA Technique
Ribosomal rnas as evolutionary chronometers D Reasons: Ancient molecules Functionally constant Universally distributed Moderately well conserved in sequence across broad phylogenetic distances
Ribosomal RNAs as Evolutionary Chronometers Reasons: • Ancient molecules • Functionally constant • Universally distributed • Moderately well conserved in sequence across broad phylogenetic distances
The 16s rRNA or 18S rRNA Technique 705 ribosome 30S subunit
The 16S rRNA or 18S rRNA Technique
The 16srRNA or 18S rRNA Technique 口 In Prokaryotes: SS rRNA is too small. contains limited info 23S rRNA iS too large, too difficult to manage 16srRNA has the right size for studies 口 In Eukaryotes 18S rRNA iS used for phylogenetic measurements
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 phylogenetic measurements
The 16S rRNA or Organismic Isolate DNA 18S rRNA Techniqe ue 16 S RNA gene種 Heat to separate strands: add specific primers Primer extension with DNA polymerase Repeat above steps for many PCR cycles to yield multiple copies of 1 6S ribosomal RNA gene Run agarose gel and check for correct sized PCR product Purify PCR product Sequence by sanger method
The 16S rRNA or 18S rRNA Technique