| Classification of Microorganisms |
Classification of Microorganisms
- Traditional classification schemes were
based on overt morphology of an organism,
its habitat, method of getting energy,
nutrition and method of replication. With
the advent of DNA and protein sequencing
many of the old categories were modified and
new ones created. In the 18th century when
classification was first formalized all
living things were placed into two kingdoms,
Plants or Animals likewise there were two
Domains: Prokaryota and Eukaryota.
- The three-domain system was introduced
by Carl Woese in 1970�s. Based on 16S rRNA
gene sequences he split the Prokaryota
domain into Eubacteria and Archaebacteria.
Their genetic sequences indicated that each
of these Domains arose separately from an
ancestor. The Domains were renamed:
Bacteria, Archaea and Eukarya.
- The biochemistry of Archaea and Bacteria
is a significant parameter in their
classification. The microbes that are
currently in the kingdom archaea was
originally grouped with Bacteria. The gross
morphology of these two Kingdoms are
similar. However the creation of a new
kingdom (Archaea) was necessary when
information from gene and protein
sequencing was combined with the unique
demands of the niche these organisms
occupy.
- One of the fundamental functions of
classification and taxonomy is to determine
how organisms are related both physically
and in time. One way to do this is to
monitor the rate of change in a shared
trait, like ribosome sequences.
- A major goal of classification and
taxonomy is describe how organisms are
related physically and evolutionarily. One
method to do this is to monitor the rate of
change in a shared trait, like ribosome
sequences.
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