L5: Microbial Diversity and Tree of life Flashcards
What are the benefits of taxonomy
- universal labelling
- organisational
What are the three interelated parts of taxonomy
- classification: arranging into groups
- nomencalture: assinging names
- identification: determ the taxon to see characteristics + isolate
How does microbial taxonomy work
- Linnean system
- use genus + species
- not much structural diversity but metabolically diverse
Go big to small in categories
- domain
- phylum
- order
- family
- genus
- species
- strain
What is the historcial approach to taxonomy
- isolate the species
- perform tests
- compare to Manual
What tests are performed to help determine species
cell morphology
motility
energy sources
cell wall/membrane
What is the genetic approach to taxonomy
- align sequences
- comparitive analyses
- use the 16S rRNA gene
What is the 16S rRNA gene
- part of the 30s ribosome subunit that helps mRNA find ribosomes
used because
1. all bac + arch use it for transaltion meaning it must be conserved and has low mutational rat so easy to find
2. however there are hypervariable regions with high mutational rates to help distinguish phylogentic groups
get sequences
align
phlyogentic treee
calculate divergence
List genotypic approaches (5)
- 16s rNA
- GC content
- MLST
- DNA- DNA
- Whole genome sequencing
GC content
- % of genome with GC base pairs
MLST
compare house keeping genes
used for strains cause sensitive
DNA DNA hybdrisation
cheap + fast broadly asses similarities at denatured temps
cool DNA then florescence => heat to seperate the strands then hybridise together
gaps => disimilar
tight band => similar
What is whole genome sequencing
best but expensive
What is the gold standard approach
polyphasic taxonomy
regular shmegular phenotyupc traditional methods + genotypic method
Most to least abundant domains
bacterial
archeal
eukaroyic
