Name: how rrna reshaped life's domains
Uploaded: 2025-06-12T09:18:46.000Z
Duration: 1 min 21 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Biology

BIO.6

BIO.6.d

Three-Domain System of Life

Basierend auf Unterschieden in den Nukleotidsequenzen ribosomaler RNA kann alles zelluläre Leben in drei verschiedene Domänen eingeteilt werden – Bakterien, Archaeen und Eukarya. Diese drei Domänen stammen von einem gemeinsamen Vorfahren vor etwa 3,5 Milliarden Jahren ab, mit einem signifikanten horizontalen Gentransfer. Die eukaryotischen Zellen erschienen später, vor etwa 2,5 Milliarden Jahren. Die Domäne Bakterien umfasst Prokaryoten, die Peptidoglykan in ihren Zellwänden haben. Es umfasst alle pathogenen und nicht-pathogenen Prokaryoten sowie phototrophe Bakterien. Zur Domäne Archaea gehören Prokaryoten, denen Peptidoglycan in ihren Zellwänden fehlt. Diese Organismen sind oft in extremen Umgebungen zu finden und umfassen Methanogene, extreme Halophile und Hyperthermophile. Methanogene sind Anaerobier, die Methan aus Kohlendioxid und Wasserstoff produzieren. Extrem halophile Tiere benötigen hohe Salzkonzentrationen, um zu überleben. Hyperthermophile gedeihen in extrem heißen Umgebungen. Die Domäne Eukarya enthält kernhaltige Organismen, darunter Protozoen, Algen, Pilze, Pflanzen und Tiere.

das drei-domänen-system des lebens

Die Analyse ribosomaler RNA (rRNA) offenbarte drei klar unterscheidbare Zellgruppen: Eukaryoten, Prokaryoten, oder auch Bakterien, und Archaeen. Im Jahr 1978 schlug Carl R. Woese das Konzept der Dom&#228;nen vor, eine taxonomische Kategorie oberhalb der Reiche, um diese Gruppen voneinander abzugrenzen. Er argumentierte, dass Archaeen und Bakterien, trotz &#228;hnlicher Morphologie, unterschiedlichen Dom&#228;nen angeh&#246;ren. Dom&#228;nen unterscheiden sich hinsichtlich ihrer rRNA, der Struktur ihrer Membranlipide, ihrer Transfer-RNA sowie ihrer Antibiotikaempfindlichkeit.
In dieser Klassifikation geh&#246;ren Tiere, Pflanzen und Pilze zur Dom&#228;ne Eukarya, welche s&#228;mtliche eukaryotischen Organismen umfasst. Die Dom&#228;ne Bacteria besteht aus pathogenen und nicht-pathogenen Prokaryoten, einschlie&#223;lich Boden- und Wasserarten sowie Photoautotrophen. Die Dom&#228;ne Archaea umfasst Prokaryoten, deren Zellw&#228;nde kein Peptidoglykan enthalten und die oft in extremen Umgebungen gedeihen. Zu den Archaeen z&#228;hlen Methanogene (Methanbildner), extreme Halophile (salzliebende Organismen) und Hyperthermophile (an hohe Temperaturen angepasste Arten).
Fossile Belege deuten darauf hin, dass Prokaryoten vor etwa 3,5 Milliarden Jahren entstanden, w&#228;hrend Eukaryoten sich vor rund 2,5 Milliarden Jahren entwickelten. Die Endosymbiontentheorie besagt, dass Eukaryoten durch symbiotische Beziehungen zwischen Prokaryoten entstanden sind, wobei eine Zelle innerhalb einer anderen lebte. Einst&#252;lpungen der Plasmamembran k&#246;nnten zur Ausbildung eines Zellkerns gef&#252;hrt haben, wie es bei bestimmten Bakterien, etwa Gemmata, zu beobachten ist. Im Verlauf der Evolution entwickelte sich das Nukleoplasma weiter, wobei sich Chromosomen fragmentierten und f&#252;r eine effiziente Zellteilung anpassten.
Horizontale Gentransfers zwischen den drei Dom&#228;nen wurden beobachtet; gemeinsam genutzte Gene belegen ihre vernetzte evolution&#228;re Entwicklung. So stammen beispielsweise einige Gene von Thermotoga-Bakterien vermutlich von Archaeen. Das taxonomische System entwickelt sich fortlaufend weiter und tr&#228;gt dazu bei, die Beziehungen zwischen Organismen sowie ihre Evolutionsgeschichte zu verstehen, insbesondere mit der Entdeckung neuer Arten.

Das Drei-Domänen-System des Lebens

Die Analyse ribosomaler RNA (rRNA) offenbarte drei klar unterscheidbare Zellgruppen: Eukaryoten, Prokaryoten, oder auch Bakterien, und Archaeen. Im Jahr ...

Education

Lehre

JoVE Core

Microbiology

Mikrobiologie

Unit

Einheit

Microbial Diversity

Mikrobielle Diversität

KEY TERMS AND CONCEPTS

ZENTRALE BEGRIFFE UND KONZEPTE

how rrna reshaped life's domains

Ribosomal RNA, or rRNA, changed how scientists classify life. Sequence analysis showed three major groups of cells: eukaryotes, bacteria, and archaea. In 1978, Carl R. Woese proposed domains as a taxonomic level above kingdoms to separate these groups.

Woese also showed that archaea and bacteria are not the same, even though they can look similar. The three domains differ in rRNA, membrane lipid structure, transfer RNA, and sensitivity to antibiotics. These differences helped scientists build a clearer picture of relatedness among organisms.

Domain Eukarya includes animals, plants, fungi, and other eukaryotic organisms. Domain Bacteria includes prokaryotes that can be pathogenic or nonpathogenic. Many bacteria live in soil and water, and some are photoautotrophs, meaning they use light to make food.

Domain Archaea includes prokaryotes that do not have peptidoglycan in their cell walls. Many archaea live in extreme environments. This group includes methanogens, which produce methane, extreme halophiles, which like salt, and hyperthermophiles, which are adapted to high heat.

Fossil evidence suggests that prokaryotes first appeared about 3.5 billion years ago. Eukaryotes evolved later, around 2.5 billion years ago. The endosymbiotic theory explains this change by suggesting that one prokaryote lived inside another in a symbiotic relationship.

Membrane infoldings may also have helped form the nucleus. Some bacteria, such as Gemmata, show this kind of structure. Over time, the nucleoplasm evolved, and chromosomes fragmented in ways that may have supported efficient cell division.

Scientists also know that the three domains share genes through horizontal gene transfer. This means genes can move between organisms that are not direct relatives. For example, some genes in Thermotoga bacteria likely came from archaea.

The system of classification continues to change as new species are found. It helps scientists study relationships among organisms and trace evolutionary history. rRNA evidence remains a key tool for understanding how the major domains of life are connected.

How rRNA Reshaped Life's Domains

three-domain system of life

Ribosomal RNA, or rRNA, changed how scientists classify life. Sequence analysis showed three major groups of cells: eukaryotes, bacteria, and archaea. In 1978, Carl R. Woese proposed domains as a taxonomic level above kingdoms to separate these groups. Woese also showed that archaea and bacteria are not the same, even though they can look similar. The three domains differ in rRNA, membrane lipid structure, transfer RNA, and sensitivity to antibiotics. These differences helped scientists build...

microbial classification system

Naming and Ranking Microbes

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methods of classification and identification

methods-of-classification-and-identification

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bacterial phylum proteobacteria

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bacterial phylum chlamydiae

Chlamydiae Life Cycle and Host Infection

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bacterial phylum planctomycetes 

Planctomycetes Cell Structure and Life Cycle

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bacterial phylum verrucomicrobiota

Verrucomicrobiota Cell Structure and Traits

Verrucomicrobiota are a bacterial phylum with several recognized orders, and most species belong to Verrucomicrobiotales. Many members are aerobic or facultatively aerobic, which means they can use oxygen but may also grow without it. They can also ferment sugars. One exception is the genus Methylacidiphilum, which contains aerobic methanotrophs, bacteria that use methane and oxygen. These bacteria live in many different places. They are found in freshwater, marine habitats, forest soils, and...

bacterial phylum spirochaetes

Spirochete Shape, Motion, and Disease

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bacterial phylum cyanobacteria

Cyanobacteria and Oxygenic Photosynthesis

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bacterial phylum actinobacteria

Actinobacteria: Soil Bacteria and Cheese

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bacterial phylum firmicutes

Firmicutes: Bacteria, Fermentation, and Spores

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bacterial phylum bacteroidota

Gut and Environment Bacteria in Bacteroidota

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anoxygenic phototrophic bacteria

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hyperthermophilic bacteria

Heat-Loving Bacteria and Their Enzymes

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bacterial phylum tenericutes

Mycoplasmas and Wall-Less Bacteria

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other unique bacteria

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diversity of archaea i

Archaea Extremes: Euryarchaeota

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diversity of archaea ii

New Archaea Phyla and Their Roles

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diversity of archaea iii

Crenarchaeota in Extreme Hot Springs

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diversity of archaea iv

How Hyperthermophilic Archaea Survive Heat

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fungal group zygomycota

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fungal phylum microsporidia

Microsporidia Spores and Host Infection

Microsporidia are unicellular fungi that live as obligate intracellular parasites. They were first classified as protists, but phylogenetic, molecular, and structural evidence later linked them to the Chytridiomycota. These non-motile organisms infect many animal hosts, including humans, and depend heavily on the host cell to survive. Their cells are very small, usually 2 to 5 micrometers wide. Microsporidia form spores with a chitin shell, which helps them resist the outside environment. The...

fungal phylum ascomycota

Ascomycota: Sac Fungi and Their Spore Cycle

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fungal phylum basidiomycota

Basidiomycota: Mushrooms, Spores, and Ecological Roles

Basidiomycota is a major group of fungi that includes mushrooms, puffballs, decomposers, symbionts, plant pathogens, and some edible species. These fungi matter in ecosystems, agriculture, and medicine. A key feature of this phylum is the basidium, a small club-shaped structure that makes basidiospores. Many basidiomycetes form visible fruiting bodies called basidiocarps. The life cycle starts when a haploid basidiospore germinates into monokaryotic mycelium. When two compatible mycelia fuse,...

overview of algae

Algae Structure, Habitats, and Reproduction

Algae are simple eukaryotic photoautotrophs that live in many habitats and show a wide range of body forms. They contain chlorophyll and carry out oxygenic photosynthesis. They belong to the kingdom Archaeplastida, which also includes red and green algae and land plants. Unlike other protists with chloroplasts from secondary endosymbiosis, red and green algae came from primary endosymbiotic events. Algae can look very different from one another. Some are large brown kelp in coastal waters,...

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Red Algae Pigments, Shapes, and Uses

Red algae are phototrophic organisms found mostly in marine environments. Some species also live in freshwater or on land. They may be unicellular or multicellular, and some multicellular forms grow large enough to be seen easily. These algae contain chlorophyll a, but their chloroplasts do not contain chlorophyll b. Instead, they use phycobiliproteins, which are light-harvesting pigments like those found in cyanobacteria. The red color seen in many species comes from phycoerythrin, an...

green algae

Green Algae: Forms, Habitats, and Roles

Green algae are photosynthetic organisms with chlorophylls a and b in their chloroplasts. These pigments give them a green color. They differ from red algae because they lack phycobiliproteins, the pigments that produce red or blue-green tones in red algae. In pigment makeup, green algae are close to plants, and they share a close evolutionary relationship with them. Green algae belong to Phylum Chlorophyta in the Kingdom Archaeplastida. They are usually divided into two main groups:...

other algae

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Stramenopile algae include diatoms, golden algae, and brown algae. These phototrophic microorganisms have flagella with many short, hairlike extensions. That feature gave the group its name, which comes from Latin words meaning “straw” and “hair.” Diatoms are unicellular, photosynthetic eukaryotes, and more than 200 genera are known. They are important parts of plankton in both marine and freshwater ecosystems. Their most distinctive feature is a silica-based cell wall called a frustule. This...

overview of protists

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diversity of protists i

Excavata Protists and Their Adaptations

Excavata protists show many different ways of living, from photosynthesis to parasitism. This group includes organisms that can use chemical energy, light, or both. Some also live in low-oxygen, or anaerobic, environments where they survive without normal oxygen-based metabolism. Among the main Excavata groups are diplomonads and parabasalids. These are flagellated protists, meaning they move with whip-like tails, and they lack mitochondria and chloroplasts. They often live in anoxic habitats,...

diversity of protists ii

Alveolates: Ciliates, Dinoflagellates, Apicomplexans

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diversity of protists iii

Rhizaria: Pseudopods, Tests, and Skeletons

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diversity of protists iv

Amoebozoa: Movement and Life Cycles

Amoebozoa are a diverse group of terrestrial and aquatic protists. They move and feed with lobe-shaped pseudopodia. This feature sets them apart from Rhizaria, which have threadlike pseudopodia. The group includes gymnamoebas, entamoebas, and the plasmodial and cellular slime molds. Phylogenetic evidence also shows that Amoebozoa split from a lineage that later gave rise to fungi and animals. Gymnamoebas are free-living protists that live in water and soil. They move by amoeboid movement,...

key terms and concepts

Learn how rRNA analysis led to the three-domain system, separating bacteria, archaea, and eukaryotes while revealing their evolutionary links.

How rRNA Reshaped Life's Domains | JoVE K12

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How rRNA Reshaped Life's Domains

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