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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, etc....
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
Bb
Next
Lecture
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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