The Microbial Tree of Life

Life, in a nut-shell, consists of...

Three domains: Archaea, Bacteria, and Eukarya 

Archaea are unicellular organisms lacking a nucleus as well as peptidoglycan in their cell walls.  Once grouped with the bacteria, Archaeans possess distinctive membrane lipids.

Bacteria are also unicellular organisms lacking a nucleus, possess distinctive ribosomes and initiator tRNA, and generally contain peptidoglycan in their cell walls. 

Eukarya are much more complex than the Archaea and Bacteria.  These organisms are made up of one or more complex cells in which genetic material is contained in nuclei.  They also possess membrane bound organelles which carry out specific functions for the cell.  Kingdoms Fungi and Protista are members of the Eukarya Domain.

 All of which contain organisms that...
  • Have one or more cells
  • Have genetic information which is used to reproduce itself
  • Are genetically related and have evolved
  • Can convert molecules obtained from the environment into new biological molecules
  • Can extract energy from the environment and use it to do work
  • Can regulate their internal environment