Name: how photosynthesis changed earth
Uploaded: 2026-03-12T13:57:27.000Z
Duration: 1 min 26 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Earth's Systems

9-12.EVS.3.4

Origin of Photosynthesis

Die Photosynthese, der Prozess, bei dem photosynthetische Organismen Lichtenergie in chemische Energie umwandeln, begann wahrscheinlich vor etwa 3,5 Milliarden Jahren.Die früheste Form der Photosynthese war wahrscheinlich anoxygen, wobei mehrere alternative Elektronendonoren wie Schwefelwasserstoff oder Eiseneisen verwendet wurden und Schwefel oder oxidiertes Eisen statt Sauerstoff freigesetzt wurden.Später entwickelten Cyanobakterien die Fähigkeit, sauerstoffhaltige Photosynthese durchzuführen, indem Wasser als Elektronenspender verwendet und Sauerstoff als Nebenprodukt freigesetzt wird.Der von Cyanobakterien freigesetzte Sauerstoff reagierte mit gelöstem Eisen in den Ozeanen und bildete unlösliche Eisenoxide, die sich als gebänderte Eisenformationen auf dem Meeresboden absetzten.Gleichzeitig bildeten Cyanobakterien geschichtete mikrobielle Matten, die schließlich zu Stromatoliten fossilisierten.Da der Großteil des gelösten Eisens im Ozean oxidierte und große Sauerstoffsenken zunehmend gesättigt wurden, konnte sich schließlich freier Sauerstoff in der Atmosphäre ansammeln.Dieser Anstieg des atmosphärischen Sauerstoffs löste vor etwa 2,4 Milliarden Jahren das Große Oxidationsereignis aus, das den aeroben Stoffwechsel und die Bildung der Ozonschicht ermöglichte.

ursprung der photosynthese

Die Photosynthese stellt einen grundlegenden biologischen Prozess dar, der die Erdatmosphäre veränderte und den Weg für komplexes Leben ebnete. Vor etwa 3,4–3,8 Milliarden Jahren entstanden die frühesten photosynthetischen Organismen, die Lichtenergie nutzten, um organische Verbindungen herzustellen. Diese anoxygenhaltigen Phototrophe verwendeten Elektronendonoren wie Schwefelwasserstoff (H₂S) oder eisenhaltiges Eisen (Fe²⁺) anstelle von Wasser und setzten keinen molekularen Sauerstoff (O₂) als Nebenprodukt frei. Verschiedene Gruppen, darunter grüner Schwefel und violette Bakterien, trugen zu dieser frühen phototrophen Vielfalt bei.Ein bedeutender evolutionärer Meilenstein war die Entwicklung der sauerstoffhaltigen Photosynthese durch Cyanobakterien. Diese Mikroorganismen nutzten Wasser als Elektronenspender und produzierten als Nebenprodukt molekularen Sauerstoff. Cyanobakterien besiedelten flache marine Umgebungen und bildeten ausgedehnte mikrobielle Matten. Im Laufe der Zeit sammelten diese Matten Sedimente und Niederschläge an und versteinerten sich zu Stromatoliten – einige der ältesten bekannten Lebensbelege. Mit dem lokalen Anstieg des Sauerstoffgehalts reagierte es mit reichlich gelöstem Eisen im Meerwasser und fiel als Eisenoxide aus. Diese Oxide setzten sich auf den Meeresboden ab und bildeten gebänderte Eisenformationen (BIFs), die als wichtige geologische Marker früher atmosphärischer Veränderungen dienen.Nachdem der Großteil des ozeanischen Eisens oxidiert war, begann überschüssiger Sauerstoff in die Atmosphäre zu diffundieren, was vor etwa 2,4 Milliarden Jahren das Große Oxidationsereignis (GOE) auslöste. Dieser Übergang veränderte die Chemie und Biologie der Erde drastisch. Der Anstieg des atmosphärischen Sauerstoffs ermöglichte die Entwicklung der aeroben Atmung, die weit mehr Energie liefert als der anaerbe Stoffwechsel. Sie führte auch zur Bildung der stratosphärischen Ozonschicht (O₃), die den Planeten vor schädlicher ultravioletter Strahlung schützte und den Weg für die Ausbreitung von Leben auf Land ebnete.Während die GOE evolutionäre Innovationen förderte, führte sie auch oxidativen Stress ein und führte zum Aussterben vieler anaerob Organismen. Dennoch bleibt das Aufkommen der sauerstoffhaltigen Photosynthese eine der bedeutendsten evolutionären Entwicklungen in der Erdgeschichte.

Ursprung der Photosynthese

Photosynthesis represents a fundamental biological process that transformed Earth's atmosphere and paved the way for complex life. Emerging roughly ...

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Education

Lehre

JoVE Core

Microbiology

Mikrobiologie

Unit

Einheit

Microbial Evolution

Mikrobielle Evolution

KEY TERMS AND CONCEPTS

SCHLÜSSELBEGRIFFE UND KONZEPTE

how photosynthesis changed earth

Photosynthesis changed Earth’s atmosphere and made complex life possible. It began about 3.4 to 3.8 billion years ago, when the first photosynthetic organisms used light energy to build organic compounds. These early organisms were anoxygenic phototrophs, which means they made food from light but did not release oxygen.

Early photosynthesis used hydrogen sulfide (H2S) or ferrous iron (Fe2+) as electron donors instead of water. Because of that, it did not produce molecular oxygen (O2) as a waste product. Green sulfur bacteria and purple bacteria were among the groups that helped shape this early phototrophic diversity.

A major turning point came with cyanobacteria and oxygenic photosynthesis. Cyanobacteria used water as the electron donor and released oxygen. They lived in shallow marine environments and formed large microbial mats. Over time, those mats trapped sediments and precipitates and later became stromatolites, which are some of the oldest evidence of life.

As oxygen built up in local waters, it reacted with dissolved iron in the sea. This formed iron oxides that sank to the seafloor and created banded iron formations, or BIFs. These rocks are important markers of early changes in Earth’s atmosphere and oceans.

After most of the iron in the oceans had been oxidized, oxygen began to enter the atmosphere. This led to the Great Oxidation Event, or GOE, around 2.4 billion years ago. The rise in oxygen changed Earth’s chemistry and biology in major ways.

More oxygen allowed aerobic respiration, which releases much more energy than anaerobic metabolism. It also helped form the stratospheric ozone (O3) layer, which protects life from harmful ultraviolet radiation. That protection helped set the stage for life to spread onto land.

The Great Oxidation Event also had harmful effects. Oxygen created oxidative stress and caused many anaerobic organisms to die out. Even so, the rise of oxygenic photosynthesis remains one of the most important events in Earth’s history.

How Photosynthesis Changed Earth

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key terms and concepts

Explore how early photosynthesis, cyanobacteria, stromatolites, and the Great Oxidation Event transformed Earth’s atmosphere and enabled complex life.

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9-12.EVS.3.5

How Photosynthesis Changed Earth

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