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Classification three domain system

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Divya Chetnani
Divya Chetnani

The document discusses the three domain system of life - Archaea, Bacteria, and Eukarya. It provides background on how Archaea were identified as a unique third domain based on differences in ribosomal RNA from other prokaryotes. Key differences between the three domains are outlined, including cellular structure, genetics, metabolism, and environments inhabited. Archaea share some similarities with both bacteria and eukaryotes but are sufficiently distinct to be placed in their own domain.

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Introduction To Three Domain System Divya Chetnani M.Sc BT, Department of Biotechnology Shree M & N Virani Science College(Autonomous), Rajkot - 360005, Gujarat, India. 1 Divya Swaminarayan
History Of Phylogenetic Classification •Until the middle of the 20th century, biologists classified all living things as either a plant or an animal. But this system failed to accommodate fungi, protists and bacteria. • In 1969., the classification system evolved to what was known as Five Kingdoms — prokaryotes (bacteria) and eukaryotes (plants, animals, fungi, protists). •Eukaryotes are characterized by the presence of nuclei, cytoskeletons, and internal membranes in their cells. 2 Divya Swaminarayan
• In the late 1970s, Dr. Carl Woese and his colleagues at the University of Illinois identified a group of microorganisms whose genetic makeup was vastly different from other bacteria. • So they divided prokaryotic life into what they called archaeabacteria and eubacteria. • However, they later concluded that "archaeabacteria" were sufficiently different as to not be bacteria at all. So the groups were renamed to archaea and bacteria. 3 Divya Swaminarayan
There are three domains of life: Bacteria (also known as Eubacteria), Archaea, and Eukarya. The Bacteria and Archaea are made up entirely of microorganisms; the Eukarya contains plants, animals, and microorganisms such as fungi and protists. 4 Divya Swaminarayan
• Archaea were split off as a third domain because of the large differences in their ribosomal RNA structure. The particular RNA molecule sequenced, known as 16s rRNA, is present in all organisms and always has the same vital function, the production of proteins. • Because this function is so central to life, organisms with mutations of its 16s rRNA are unlikely to survive, leading to great stability in the structure of this nucleotide over many generations. • Functions: • Like the large (23S) ribosomal RNA, it has a structural role, acting as a scaffold defining the positions of the ribosomal proteins. • Interacts with 23S, aiding in the binding of the two ribosomal subunits (50S+30S) • 16s rRNA is also large enough to retain organism-specific information, but small enough to be sequenced in a manageable amount of time. • In 1977, Carl Woese, a microbiologist studying the genetic sequencing of organisms, developed a new sequencing method that involved splitting the RNA into fragments that could be sorted and compared to other fragments from other organisms. • The more similar the patterns between species were, the more closely related the organisms. 5 Divya Swaminarayan
• Archaea: Archaea is derived from the Greek word archaios, meaning “ancient” or “primitive,” and indeed some archaea exhibit characteristics worthy of that name. • Members of the archaea include: Pyrolobus fumarii, which holds the upper temperature limit for life at 113 °C (235 °F) and was found living in hydrothermal vents. • Species of Picrophilus, which were isolated from acidic soils in Japan and are the most acid-tolerant organisms known—capable of growth at around pH 0. • And the methanogens, which produce methane gas as a metabolic by- product and are found in anaerobic environments, such as in marshes, hot springs, and the guts of animals, including humans. 6 Divya Swaminarayan
• Eubacteria:Eubacteria, known as "true bacteria," are prokaryotic (lacking nucleus) cells that are very common in human daily life kill thousands upon thousands of people each year, but also serve as antibiotics producers and food digesters in our stomachs. • We use Eubacteria to produce drugs, wine, and cheese. • They lacks a membrane-bound nucleus (karyon), mitochondria, or any other membrane-bound organelle. • Eukaryote: A eukaryote is any organism whose cells have a nucleus and other organelles enclosed within membranes. • Eukaryotes belong to the taxon Eucarya or Eukaryota. • The defining feature that sets eukaryotic cells apart from prokaryotic cells (Bacteria and Archaea) is that they have membrane-bound organelles, especially the nucleus, which contains the genetic material and is enclosed by the nuclear envelope. 7 Divya Swaminarayan
8 Divya Swaminarayan
• Archaea and bacteria are generally similar in size and shape, although a few archaea have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. • The RNA polymerase in archaea is similar to RNA polymerase II in eukaryotes. • Archaea resembles eukaryotes more than bacteria. Their ribosomes work more like eukaryotic ribosomes than bacterial ribosomes. • Lipids in membranes from Archaea are unique, containing ether linkages between the glycerol backbone and the fatty acids, instead of ester linkages. • The cells walls of Archaea are chemically and structurally diverse and do not contain peptidoglycan. Haloquadratum walsbyi. 9 Divya Swaminarayan
• Despite this morphological similarity to bacteria, archeae possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably the enzymes involved in transcription and translation. . • Archaea reproduce asexually by binary fission, fragmentation, or budding; unlike bacteria and eukaryotes, no known species forms spores. • Although Archaea are prokaryotic, they are more closely related to Eukarya and thus cannot be placed within either the Bacteria or Eukarya domains. • Here are other major differences between the three domains. 10 Divya Swaminarayan
Characteristic Eubacteria Archeae Eukaryotes Cell Type Prokaryote Prokaryote Eukaryote Cell size Usually 0.5-4µ Usually 0.5-4µ >5µ Cell wall Made of peptidoglycan Does not contain peptidoglycan In plants and fungi, composed of polysaccharides First amino acid during protein synthesis Formylmethionine Methionine Methionine DNA Mostly circular chromosome and plasmids Circular chromosome and plasmids Linear chromosome, rarely plasmids Histones No Yes Yes Organelles No No Yes Ribosomes 70S 70S 80S 11 Divya Swaminarayan
Predominantly multicellular no no yes Membrane lipids ester-linked* yes No (Archaea membrane lipids are ether-linked) yes Photosynthesis with chlorophyll yes no yes Growth above 80o C yes yes no Operons yes yes no Capping and poly-A tailing of mRNA no no yes Transcription factors required yes no yes Methanogenesis no yes no Nitrification yes no no Introns in t-RNA absent present present Introns in m-RNA absent absent present 12 Divya Swaminarayan
Capping and poly- A tailing of mRNA no no yes Transcription factors required yes no yes Methanogenesis no yes no Nitrification yes no no Denitrification yes yes no Nitrogen Fixation yes yes no Chemolithotrophy yes yes no Gas vesicles present yes yes no Sensitive to chloramphenicol, kanamycin and streptomycin yes no no Sensitive to anisomysin no yes yes 13 Divya Swaminarayan
Cytological features Eubacteria Archeae Eukaryotes Nucleus No No Yes Cytoskeleton No No Yes Organelles (mitochondria,chlo roplasts, Golgi apparatus, endopla smic reticulum) No No Yes 14 Divya Swaminarayan
Molecular features DNA topology Negatively supercoiled Relaxed or positively supercoiled (in hyperthermophilic Archaea that contain reverse gyrase) Negatively supercoiled Promoterstructure Two conserved boxes at - 10 (TATAAT) and - 35 (TTGACA) from transcription start site TATA box and/or initiator element TATA box and/or initiator element 15 Divya Swaminarayan
RNA polymerase One type; relatively simple subunit composition; binds directly to promoter (can be footprinted) One type; complex subunit structure (subunit pattern, genes, and serological properties similar to eukaryal RNA polymerase II) Three types; complex subunit compositions Poly(A) tails in RNA Short Short (avg. 12 bases in length) Long Typical Organisms Entric bacteria and cyanobacteria Methanogens,halo philes,extremophil es Algae, Protozoa, Fungi, Plants and Animals 16
17 Divya Swaminarayan
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Classification three domain system

  • 1. Introduction To Three Domain System Divya Chetnani M.Sc BT, Department of Biotechnology Shree M & N Virani Science College(Autonomous), Rajkot - 360005, Gujarat, India. 1 Divya Swaminarayan
  • 2. History Of Phylogenetic Classification •Until the middle of the 20th century, biologists classified all living things as either a plant or an animal. But this system failed to accommodate fungi, protists and bacteria. • In 1969., the classification system evolved to what was known as Five Kingdoms — prokaryotes (bacteria) and eukaryotes (plants, animals, fungi, protists). •Eukaryotes are characterized by the presence of nuclei, cytoskeletons, and internal membranes in their cells. 2 Divya Swaminarayan
  • 3. • In the late 1970s, Dr. Carl Woese and his colleagues at the University of Illinois identified a group of microorganisms whose genetic makeup was vastly different from other bacteria. • So they divided prokaryotic life into what they called archaeabacteria and eubacteria. • However, they later concluded that "archaeabacteria" were sufficiently different as to not be bacteria at all. So the groups were renamed to archaea and bacteria. 3 Divya Swaminarayan
  • 4. There are three domains of life: Bacteria (also known as Eubacteria), Archaea, and Eukarya. The Bacteria and Archaea are made up entirely of microorganisms; the Eukarya contains plants, animals, and microorganisms such as fungi and protists. 4 Divya Swaminarayan
  • 5. • Archaea were split off as a third domain because of the large differences in their ribosomal RNA structure. The particular RNA molecule sequenced, known as 16s rRNA, is present in all organisms and always has the same vital function, the production of proteins. • Because this function is so central to life, organisms with mutations of its 16s rRNA are unlikely to survive, leading to great stability in the structure of this nucleotide over many generations. • Functions: • Like the large (23S) ribosomal RNA, it has a structural role, acting as a scaffold defining the positions of the ribosomal proteins. • Interacts with 23S, aiding in the binding of the two ribosomal subunits (50S+30S) • 16s rRNA is also large enough to retain organism-specific information, but small enough to be sequenced in a manageable amount of time. • In 1977, Carl Woese, a microbiologist studying the genetic sequencing of organisms, developed a new sequencing method that involved splitting the RNA into fragments that could be sorted and compared to other fragments from other organisms. • The more similar the patterns between species were, the more closely related the organisms. 5 Divya Swaminarayan
  • 6. • Archaea: Archaea is derived from the Greek word archaios, meaning “ancient” or “primitive,” and indeed some archaea exhibit characteristics worthy of that name. • Members of the archaea include: Pyrolobus fumarii, which holds the upper temperature limit for life at 113 °C (235 °F) and was found living in hydrothermal vents. • Species of Picrophilus, which were isolated from acidic soils in Japan and are the most acid-tolerant organisms known—capable of growth at around pH 0. • And the methanogens, which produce methane gas as a metabolic by- product and are found in anaerobic environments, such as in marshes, hot springs, and the guts of animals, including humans. 6 Divya Swaminarayan
  • 7. • Eubacteria:Eubacteria, known as "true bacteria," are prokaryotic (lacking nucleus) cells that are very common in human daily life kill thousands upon thousands of people each year, but also serve as antibiotics producers and food digesters in our stomachs. • We use Eubacteria to produce drugs, wine, and cheese. • They lacks a membrane-bound nucleus (karyon), mitochondria, or any other membrane-bound organelle. • Eukaryote: A eukaryote is any organism whose cells have a nucleus and other organelles enclosed within membranes. • Eukaryotes belong to the taxon Eucarya or Eukaryota. • The defining feature that sets eukaryotic cells apart from prokaryotic cells (Bacteria and Archaea) is that they have membrane-bound organelles, especially the nucleus, which contains the genetic material and is enclosed by the nuclear envelope. 7 Divya Swaminarayan
  • 9. • Archaea and bacteria are generally similar in size and shape, although a few archaea have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. • The RNA polymerase in archaea is similar to RNA polymerase II in eukaryotes. • Archaea resembles eukaryotes more than bacteria. Their ribosomes work more like eukaryotic ribosomes than bacterial ribosomes. • Lipids in membranes from Archaea are unique, containing ether linkages between the glycerol backbone and the fatty acids, instead of ester linkages. • The cells walls of Archaea are chemically and structurally diverse and do not contain peptidoglycan. Haloquadratum walsbyi. 9 Divya Swaminarayan
  • 10. • Despite this morphological similarity to bacteria, archeae possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably the enzymes involved in transcription and translation. . • Archaea reproduce asexually by binary fission, fragmentation, or budding; unlike bacteria and eukaryotes, no known species forms spores. • Although Archaea are prokaryotic, they are more closely related to Eukarya and thus cannot be placed within either the Bacteria or Eukarya domains. • Here are other major differences between the three domains. 10 Divya Swaminarayan
  • 11. Characteristic Eubacteria Archeae Eukaryotes Cell Type Prokaryote Prokaryote Eukaryote Cell size Usually 0.5-4µ Usually 0.5-4µ >5µ Cell wall Made of peptidoglycan Does not contain peptidoglycan In plants and fungi, composed of polysaccharides First amino acid during protein synthesis Formylmethionine Methionine Methionine DNA Mostly circular chromosome and plasmids Circular chromosome and plasmids Linear chromosome, rarely plasmids Histones No Yes Yes Organelles No No Yes Ribosomes 70S 70S 80S 11 Divya Swaminarayan
  • 12. Predominantly multicellular no no yes Membrane lipids ester-linked* yes No (Archaea membrane lipids are ether-linked) yes Photosynthesis with chlorophyll yes no yes Growth above 80o C yes yes no Operons yes yes no Capping and poly-A tailing of mRNA no no yes Transcription factors required yes no yes Methanogenesis no yes no Nitrification yes no no Introns in t-RNA absent present present Introns in m-RNA absent absent present 12 Divya Swaminarayan
  • 13. Capping and poly- A tailing of mRNA no no yes Transcription factors required yes no yes Methanogenesis no yes no Nitrification yes no no Denitrification yes yes no Nitrogen Fixation yes yes no Chemolithotrophy yes yes no Gas vesicles present yes yes no Sensitive to chloramphenicol, kanamycin and streptomycin yes no no Sensitive to anisomysin no yes yes 13 Divya Swaminarayan
  • 14. Cytological features Eubacteria Archeae Eukaryotes Nucleus No No Yes Cytoskeleton No No Yes Organelles (mitochondria,chlo roplasts, Golgi apparatus, endopla smic reticulum) No No Yes 14 Divya Swaminarayan
  • 15. Molecular features DNA topology Negatively supercoiled Relaxed or positively supercoiled (in hyperthermophilic Archaea that contain reverse gyrase) Negatively supercoiled Promoterstructure Two conserved boxes at - 10 (TATAAT) and - 35 (TTGACA) from transcription start site TATA box and/or initiator element TATA box and/or initiator element 15 Divya Swaminarayan
  • 16. RNA polymerase One type; relatively simple subunit composition; binds directly to promoter (can be footprinted) One type; complex subunit structure (subunit pattern, genes, and serological properties similar to eukaryal RNA polymerase II) Three types; complex subunit compositions Poly(A) tails in RNA Short Short (avg. 12 bases in length) Long Typical Organisms Entric bacteria and cyanobacteria Methanogens,halo philes,extremophil es Algae, Protozoa, Fungi, Plants and Animals 16
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