Systemic Biology... the Classification of Organisms is done by Taxonomists:  
                                                        
In Biological taxonomy, Kingdom was (historically) the highest rank. Based upon morphology we
      see a six kingdom system
:   Archaea & Bacteria (= Monera), Protista, Fungi, Animalia, & Plantae.
      Each kingdom is subdivided into smaller groups called
phyla (or "divisions"). 

Recent molecular evidence places all Living Organisms into a higher rank, a DOMAIN...
                                                         BACTERIA    -   true bacteria
                  3 DOMAINS*
NAS-8           ARCHAEA     -   ancient prokaryotes (bacteria)
                                                         EUCARYA     -    modern eukaryotes   

   
Carl Woese established new divisions of life based upon molecular similarity of rRNA.
   
All cells are known to contain the same organelle - the ribosome, site of protein synthesis.
   Woese compared the nucleotide sequences of 
small-unit rRNA* 
from many species...
   thus... 
rRNA...  is FOUND in ALL cells with ribosomes.

   therefore Woese hypothesized"
           
if all cells are derived from a common ancestral cell[NAS-1], their rRNA sequence changes
            over evolutionary time can indicate
divergence (loss of relatedness)
* through phylogeny.
            So Woese observed rRNA sequences that might different from eukaryotes & prokaryotes.
.


 

 

 

 

 

 

 

 

 

 

 

 
based upon comparisons of many cells rRNA sequences, from numerous prokaryotic
               & eukaryotic species, Woese described 3 Domains...
 

  
     the BACTERIA, as single celled life without nuclei,
               are akin to all common prokaryotes (bacteria), but do look similar to Archaea

   
     the ARCHAEA, a prokaryotic-like group of single-celled organisms that
               thrive in extreme environments:      acid springs
                             "
extremophiles"                 arctic ice,
                                                                       hydrothermal vents at deep oceans volcanoes,
                                                                       within crevices of solid rock in mines, et
c....
               this group contains distinctive and varied chemical processes and a unique genetic makeup
  
    

     the EUKARYA
, which encompass all life based upon cells with nuclei, including
               plants, animals, fungi, and single celled protists.

        by comparing similar & divergent sequences, the RNA phylogeny tree produced,
        a tree with 
3 distinct branches, the 3 Domains
.             comparing the 3 Domainslater
 
   
back 
                                            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


                                                                                                  
and within the more traditional divisions of life we describe the...                [Collage]
  

   
5 KINGDOMS - a primary classification of organisms reflecting
                               fundamental patterns of relationships in the natural world  
              
                                                   

       MONERA    -  single celled, microscopic bacteria &  archaea;  most successful of organisms

       PROTISTA  -  algae/protozoans; unicellular eucaryotes

       PLANTAE    -  contains plants, photosynthetic organism with cellulosic cell walls

       FUNGI        -  contains molds, yeasts, & mushrooms, organisms that decompose dead organisms

       ANIMALIA -  kingdom that contains animals; organisms that eat other organisms &
                                                  lack cellulosic cell walls;   often motile

                                                                 
Campbell - Concept Activities - chapter 1.2 - Classifying Schemes.
         

               copyright c2023     Last update - Thursday, March 07, 2019
   back     Charles Mallery,    Biology 150, Department of Biology,   University of Miami,  Coral Gables, FL 33124
              
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