Microbial DIversity: Classification of Life

Germs

Micro

Viruses

Viruses are not cells, they are replicated only when they are in a living host cell

Classification

Putting things in classes

Taxonomy

Giving names to things

Phylogeny

Is the 'tree of life'

Systematics

The process of trying to classify organisms according to their phylogeny

Binomial Nomenclature

Uses the Genus and Species name to identify all organisms

Staphylococcus aureus

A form of staphylococci that commonly infects wounds and causes serious problems such as toxic shock syndrome or produces food poisoning

Escherichia coli

Discovered by Theodor Escherich 1857

Determinative classification

Based on Traits

Phylogenetic classification

Based on evolution

How to determine evolutionary relationships?

The last ancestor of a group of species had the same rRNA sequence
The more differences in rRNA sequence the more distantly related any two species are

Carl Woese

Three domain based on r RNA (eukarya, bacteria, archaea) & discovered archaea

Archaea

No nucleus
Distinct features from bacteria
Live in extreme environments
Include:
' Methanogens
' Extreme halophiles
' Extreme thermophiles

Tree of Life

A diagram depicting the genealogical relationships of all living organisms on Earth (phylogenetic), with a single ancestral species at the base.