Name: how prokaryotes survive without a nucleus
Uploaded: 2023-04-30T10:29:03.000Z
Duration: 1 min 28 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

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From Molecules to Organisms- Structures and Processes

LS.Bio.1.4

Prokaryotic Cells

Zu den Prokaryoten gehören Archaeen und Bakterien, einfache einzellige Organismen, denen membrangebundene Organellen fehlen.
Diese Organismen sind von einer selektiv durchlässigen Plasmamembran umgeben, die zelluläre Bestandteile umschließt, die frei im viskosen Zytoplasma suspendiert sind.
Neben der Plasmamembran haben Bakterienzellen ein zusätzliches Maß an Schutz in Form einer Zellwand, die dazu beiträgt, ihre Gesamtform und ihren osmotischen Innendruck zu erhalten.
Die Zellwand besteht aus Peptidoglykan – einem Polymer aus Aminosäuren und Zuckern.
Einige Bakterien haben eine weitere Abwehrschicht, die sogenannte Kapsel – eine Polysaccharidschicht, die die Zelladhäsion an Oberflächen fördert.
Im Inneren der Zelle befindet sich eine einzelne, doppelsträngige DNA in einer zentralen Region, dem Nukleoid, wo sie mit frei schwebenden Proteinen interagieren kann.
Die meisten Bakterien haben auch frei schwebende kreisförmige DNA-Stücke, sogenannte Plasmide, die sich unabhängig voneinander vermehren und Überlebensvorteile wie Antibiotikaresistenz mit sich bringen können.
Einige Bakterienarten können spezifische protein- und lipidgebundene Organellen mit unterschiedlichen Funktionen enthalten.
Cyanobakterien besitzen zum Beispiel Carboxysomen und Thylakoide, um Lichtenergie für die Photosynthese zu gewinnen.

prokaryotische zellen

Prokaryoten sind kleine einzellige Organismen, die die Domänen Archaea und Bakterien umfassen. Zu den Bakterien gehören viele häufig vorkommende Mikroorganismen wie Salmonellen und E. coli, während zu den Archaeen Extremophile gehören, die in rauen Umgebungen wie Vulkanquellen leben.

Wie eukaryotische Zellen sind alle prokaryotischen Zellen von einer Plasmamembran umgeben, verfügen über genetisches Material in Form einer einzelnen, zirkulären DNA, ein Zytoplasma, das das Innere der Zelle ausfüllt, und ribosomenreiche Zellen.

Prokaryoten sind kleine einzellige Organismen, die die Domänen Archaea und Bakterien umfassen. Zu den Bakterien gehören viele häufig vorkommende Mikroorganismen wie Salmonellen und E. coli, während zu den Archaeen Extremophile gehören, die in rauen Umgebungen wie Vulkanquellen leben.

Wie eukaryontische Zellen sind alle prokaryontischen Zellen von einer Plasmamembran umgeben, verfügen über genetisches Material in Form einzelner, zirkulärer DNA, ein Zytoplasma, das das Innere der Zelle ausfüllt, und Ribosomen, die Proteine synthetisieren. Im Gegensatz zu eukaryotischen Zellen fehlt Prokaryoten jedoch ein Zellkern oder andere membrangebundene intrazelluläre Organellen. Ihre Zellbestandteile schweben frei im Zytoplasma, obwohl ihre DNA in einer Region namens Nukleoid geclustert ist.

Im Zytoplasma vieler Prokaryoten befinden sich kleine, kreisförmige, doppelsträngige DNA-Stücke, sogenannte Plasmide. Diese unterscheiden sich von der chromosomalen DNA der Zelle und tragen nur wenige spezielle Gene, die Bakterien Überlebensvorteile wie Antibiotikaresistenz verschaffen. Plasmide replizieren sich selbst und können zwischen prokaryotischen Zellen übertragen werden.

Die meisten Bakterien haben eine Zellwand aus Peptidoglycan, die außerhalb ihrer Plasmamembran liegt. Es schützt die Zelle physisch und hilft ihr, den osmotischen Druck in verschiedenen Umgebungen aufrechtzuerhalten. Viele Bakterien verfügen außerdem über eine klebrige Kapselschicht, die ihre Zellwand bedeckt und es ihnen ermöglicht, an einem Substrat oder aneinander zu haften und so zusätzlichen Schutz zu bieten.

Während Bakterien keine membrangebundenen Organellen haben, verfügen einige über Einfaltungen der Plasmamembran, die spezielle Funktionen ausführen – wie etwa die Photosynthese bei Cyanobakterien. Obwohl Prokaryoten im Vergleich zu Eukaryoten einfache Zellen sind, verfügen sie daher über einige einzigartige Strukturen, die ihnen helfen, komplexe Funktionen auszuführen und es ihnen ermöglichen, in einer Vielzahl von Umgebungen zu leben. 
einige, die Proteine synthetisieren. Im Gegensatz zu eukaryotischen Zellen fehlt Prokaryoten jedoch ein Zellkern oder andere membrangebundene intrazelluläre Organellen. Ihre Zellbestandteile schweben frei im Zytoplasma, obwohl ihre DNA in einer Region namens Nukleoid geclustert ist.

Im Zytoplasma vieler Prokaryoten befinden sich kleine, kreisförmige, doppelsträngige DNA-Stücke, sogenannte Plasmide. Diese unterscheiden sich von der chromosomalen DNA der Zelle und tragen nur wenige spezielle Gene, die Bakterien Überlebensvorteile wie Antibiotikaresistenz verschaffen. Plasmide replizieren sich selbst und können zwischen prokaryotischen Zellen übertragen werden.

Die meisten Bakterien haben eine Zellwand aus Peptidoglycan, die außerhalb ihrer Plasmamembran liegt. Es schützt die Zelle physisch und hilft ihr, den osmotischen Druck in verschiedenen Umgebungen aufrechtzuerhalten. Viele Bakterien verfügen außerdem über eine klebrige Kapselschicht, die ihre Zellwand bedeckt und es ihnen ermöglicht, an einem Substrat oder aneinander zu haften und so zusätzlichen Schutz zu bieten.

Während Bakterien keine membrangebundenen Organellen haben, verfügen einige über Einfaltungen der Plasmamembran, die spezielle Funktionen ausführen – wie beispielsweise die Photosynthese bei Cyanobakterien. Obwohl Prokaryoten im Vergleich zu Eukaryoten einfache Zellen sind, verfügen sie daher über einige einzigartige Strukturen, die ihnen helfen, komplexe Funktionen auszuführen und es ihnen ermöglichen, in einer Vielzahl von Umgebungen zu leben.

Prokaryotische Zellen

Prokaryoten sind kleine einzellige Organismen, zu denen die Domänen Archaeen und Bakterien gehören. Zu den Bakterien gehören viele gängige Mikroorganismen, wie z. B. ...

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Cells, Genomes, and Evolution

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KEY TERMS AND CONCEPTS

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how prokaryotes survive without a nucleus

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs.

Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the cytoplasm because they do not have membrane-bound intracellular organelles.

Their DNA is clustered in a region called the nucleoid. Many prokaryotes also carry plasmids, which are small, circular, double-stranded DNA molecules. Plasmids are separate from chromosomal DNA and can carry genes that give survival advantages, such as antibiotic resistance. They can also self-replicate and move between prokaryotic cells.

Most bacteria have a cell wall made of peptidoglycan outside the plasma membrane. This wall helps protect the cell and supports osmotic pressure in different environments. Many bacteria also have a sticky capsule that covers the wall and helps them attach to surfaces or to other cells. Some bacteria even have infoldings of the plasma membrane for special jobs, such as photosynthesis in cyanobacteria.

How Prokaryotes Survive Without a Nucleus

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the tree of life - bacteria, archaea, and eukaryotes

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Three Domains on the Tree of Life

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prokaryotic cells

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs. Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the...

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cytoplasm

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the nucleus

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Genetic transfer between organisms happens in two main ways: vertical gene transfer and horizontal gene transfer. These two routes explain how hereditary material moves from one generation to the next or between organisms that are not parent and offspring. Vertical gene transfer passes genes from parent to offspring during reproduction. This is the usual way genetic information is inherited in living things. Horizontal gene transfer moves genetic material between organisms outside of...

key terms and concepts

Learn how prokaryotes survive without a nucleus, from circular DNA and plasmids to peptidoglycan cell walls, capsules, and specialized membrane folds.

How Prokaryotes Survive Without a Nucleus | JoVE K12

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Life Sciences

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Heredity: Inheritance And Variation Of Traits

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From Molecules to Organisms: Structures and Processes

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Cytoplasm

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The Nucleus

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Endoplasmic Reticulum

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How Prokaryotes Survive Without a Nucleus

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