Chapter 10 Classification of Microorganisms
Taxonomy
The science of classifying organisms
o All organisms put into taxa (categories)
Provides universal names for organisms
Provides a reference for identifying organisms
Similarity among organisms
o Fewer than 10% of all organisms discovered
Systematics, or Phylogeny
The study of the evolutionary history of organisms
All Species Inventory (2001 - 2025)
o To identify all species of life on Earth
Placing Bacteria
1735- Kingdoms Plantae and Animalia (Linnaeus)
1857 - Bacteria and fungi put in the Kingdom Plantae - “Flora” (Von Nageli)
1866 - Kingdom Protists proposed for bacteria, protozoa algae, fungi, not universally
accepted (Haeckel)
1959 Kingdom Fungi
1961- Prokaryote” defined as cell in which nucleoplasm is not surrounded by a nuclear
membrane
1968 Kingdom Prokaryotae proposed (Murray)
1969 5 Kingdom System (Whittaker)
1978- Two types of prokaryotic cells found- Domain classification (Woese)
The Three Domains
Developed by Woese in 1978; based on sequences of nucleotides in rRNA
o Has mainly different rRNA, membrane lipid structure, transfer RNA molecules,
and sensitivity to antibiotics
Eukarya
o Animals, plants, fungi
Bacteria
o Pathogenic,
nonpathogenic,
photoautotrophic
prokaryotes
Archaea
o Prokaryotes with no
peptidoglycan in cell
wall
o Methanogens - reduce
CO2 and H to
methane
o Extreme halophiles -
grow in high salt
o Hyperthermophiles -
high temperatures,
deep sea vents
, Three Domain System
Key concepts:
o All organisms evolved from cells that formed over 3 billion years ago
o The DNA passed on from ancestors is described as conserved
o The Domain Eukarya includes the kingdoms Fungi, Animalia, and Plantae, as
well as protists. The Domains Bacteria and Archaea are prokaryotes
Table 10.1- Some Characteristics of Archaea, Bacteria, and Eukarya
Table 10.2 A Model of the Origin of Eukaryotes
Endosymbiotic theory-
eukaryotic cells evolved from
prokaryotic cells living inside
one another as endosymbionts
(proven by similarities between
them)
Taxonomy
The science of classifying organisms
o All organisms put into taxa (categories)
Provides universal names for organisms
Provides a reference for identifying organisms
Similarity among organisms
o Fewer than 10% of all organisms discovered
Systematics, or Phylogeny
The study of the evolutionary history of organisms
All Species Inventory (2001 - 2025)
o To identify all species of life on Earth
Placing Bacteria
1735- Kingdoms Plantae and Animalia (Linnaeus)
1857 - Bacteria and fungi put in the Kingdom Plantae - “Flora” (Von Nageli)
1866 - Kingdom Protists proposed for bacteria, protozoa algae, fungi, not universally
accepted (Haeckel)
1959 Kingdom Fungi
1961- Prokaryote” defined as cell in which nucleoplasm is not surrounded by a nuclear
membrane
1968 Kingdom Prokaryotae proposed (Murray)
1969 5 Kingdom System (Whittaker)
1978- Two types of prokaryotic cells found- Domain classification (Woese)
The Three Domains
Developed by Woese in 1978; based on sequences of nucleotides in rRNA
o Has mainly different rRNA, membrane lipid structure, transfer RNA molecules,
and sensitivity to antibiotics
Eukarya
o Animals, plants, fungi
Bacteria
o Pathogenic,
nonpathogenic,
photoautotrophic
prokaryotes
Archaea
o Prokaryotes with no
peptidoglycan in cell
wall
o Methanogens - reduce
CO2 and H to
methane
o Extreme halophiles -
grow in high salt
o Hyperthermophiles -
high temperatures,
deep sea vents
, Three Domain System
Key concepts:
o All organisms evolved from cells that formed over 3 billion years ago
o The DNA passed on from ancestors is described as conserved
o The Domain Eukarya includes the kingdoms Fungi, Animalia, and Plantae, as
well as protists. The Domains Bacteria and Archaea are prokaryotes
Table 10.1- Some Characteristics of Archaea, Bacteria, and Eukarya
Table 10.2 A Model of the Origin of Eukaryotes
Endosymbiotic theory-
eukaryotic cells evolved from
prokaryotic cells living inside
one another as endosymbionts
(proven by similarities between
them)
