Universal Tree of Life

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Universal Tree of Life

• Universal tree ids the roadmap of life. It
  depicts the evolutionary history of the cells of
  all organism and the criteria reveals 3
  dimensions.
• The root of the universal tree represents a point
  in evolutionary history when all extend life on
  earth share a common ancestor, the universal
  ancestor.

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This universal tree illustrates the hypothesis
that all of life is related and can be divided
into three major clades, often referred to as the
three domains Archaea, Bacteria, and
Eukaryota.
             

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The Three Domain

• Discovered based on comparing of sequences of the
  rRNA from different kinds of cell.
• Discovered by Carl,R Woese in 1978
• In this classification system there are 2
  prokaryotic groups. They are Bacteria Archaea.
• They have similarity in appearance.

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• In this widely accepted scheme plants,animal,
  fungi and protists are kingdoms in the domain of
  Eukarya.
• Organisms are classified into three domain
  accorging to their cell types .
• For example, Differences in r RNA, membrane lipid
  structure, transfer RNA molecule sensetivity to
  antibiotics.

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Bacteria

• Includes all pathogenic and non pathogenic
  prokaryotes.
• Found in soil,air and water.
• Characteristics
• Cell wall contains peptidoglycane.
• Closely related to eukaryotes.
• Membrane lipid is composed of straight carbon
  chains attached to glycerol by ester linkage.
• 1st amino acid in protein synthesis is
  formaldehyde.

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modern analogs all aerobic, some groups either
unidentified (yet) or lost sulfur metabolism,
thermophilic other contemporary groups  
Aquificales most deeply rooted bacterial species
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Archaea

• Archaea includes prokartotes.
• Most primitive organism.
• Donot have peptidoglycane layer in their cell
  wall.
• Membrane lipid is composed of branched carbon
  chain attached to glycerol by Ether linkage.
• Often live in Extreme environment.
• Carry out unusal metabolic process.
• 1st amino acid in protein synthesis is
  Methionine.

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• Include three mejor groups-
• Methanogens that are strict anaerobe that produce
  methane.
• Extreme halophile which require high
  concentration of salt for their survival.
• Hyperthermophile which normally grow in hot
  environment.

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Extreme Environments and Microbial
Evolution Extremophiles are extremely
diverse Typically, extremes in radiation,
temperature, salt, pressure, pH, drought,
reducing conditions Some extreme conditions
thought to prevail on ancient Earth Therefore,
Hypothesis organisms like these dominated
ancient Earth, andtheir genetic lineages are
therefore old compared to organismsadapted to
modern, more temperate, conditions Most
extremophiles are Archaea e.g.,
hyperthermophiles, halophiles, methanogens
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Phylogenetic trees representing major groups in
the Archaea, noting the positions of organisms
commonly found in extreme environments
methanogens, halophiles, and thermophiles.
(Ogunseitan 2005).
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Eukarya

• Cell type eukaryotic.
• Cell wall contains carbohydrate.
• Membrane lipid is composed of straight carbon
  chains attached to glycerol by ester linkage.
• First amino acid in protein synthesis is
  Metionone.

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• The oldest known fossils are the remains of
  prokaryotes that lived more than 3.5 billion
  years ago.
• Eukaryotic cell evolved more recently about 1.4
  billion years ago.

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Different molecules, different trees rRNA tree
provides one phylogeny, but other molecules
suggest others   For example, rRNA suggests
Eukarya more closely related to Archaea than to
Bacteria, But, mitochondrial and chloroplast
genomes suggest origin from bacteria (not
archaea)   Within bacteria, genes coding for
nitrogen fixation suggest phylogenies different
from rRNA