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

Фотосинтез, процесс, при котором фотосинтетические организмы преобразуют световую энергию в химическую, вероятно, начался около 3,5 миллиарда лет назад.Самая ранняя форма фотосинтеза, вероятно, была безкислородной, использовала несколько альтернативных доноров электронов, таких как сероводород или железо, и высвобождала серу или окисленное железо вместо кислорода.Позже цианобактерии развили способность осуществлять кислородный фотосинтез, используя воду в качестве донора электронов и высвобождая кислород как побочный продукт.Кислород, выделяемый цианобактериями, реагировал с растворённым железом в океанах, образуя нерастворимые оксиды железа, которые оседали в виде полосатых железных образований на морском дне.Тем временем цианобактерии образовали слоистые микробные маты, которые в итоге окаменели в строматолиты.По мере того как большая часть растворённого железа океана окислялась, а основные кислородные поглотители в океанах становились всё более насыщенными, свободный кислород в конечном итоге смог накапливаться в атмосфере.Это повышение уровня кислорода в атмосфере спровоцировало Великое окисление примерно 2,4 миллиарда лет назад, что позволило аэробному метаболизму и формированию озонового слоя.

Происхождение фотосинтеза

Фотосинтез представляет собой фундаментальный биологический процесс, который преобразил атмосферу Земли и проложил путь для сложной жизни. Появившись примерно 3,4–3,8 миллиарда лет назад, самые ранние фотосинтетические организмы использовали световую энергию для производства органических соединений. Эти аноксигенные фототрофы использовали доноры электронов, такие как сероводород (H₂S) или железо железа (Fe²⁺), вместо воды, и не выделяли молекулярный кислород (O₂) в качестве побочного продукта. Различные группы, включая зелёную серу и фиолетовые бактерии, внесли вклад в это раннее фототрофное разнообразие.Значимой эволюционной вехой стало развитие кислородного фотосинтеза цианобактериями. Эти микроорганизмы использовали воду в качестве донора электронов, производя молекулярный кислород как побочный продукт. Цианобактерии заселили мелководные морские среды, формируя обширные микробные маты. Со временем эти коврики накапливали осадки и осадки, превращаясь в строматолиты — одни из самых древних известных свидетельств жизни. По мере локального повышения уровня кислорода он реагировал с обильным растворённым железом в морской воде, осаживаясь в виде оксидов железа. Эти оксиды оседали на морском дне, образуя полосатые железные образования (BIF), которые служат ключевыми геологическими ориентирами ранних изменений атмосферы.После того как большая часть океанического железа была окислена, избыток кислорода начал распространяться в атмосферу, что вызвало Великое окисление (GOE) около 2,4 миллиарда лет назад. Этот переход кардинально изменил химию и биологию Земли. Увеличение кислорода в атмосфере позволило развить аэробное дыхание, которое обеспечивает гораздо больше энергии, чем анаэробный метаболизм. Это также привело к формированию стратосферного озонового слоя (O₃), который защитил планету от вредного ультрафиолетового излучения и проложил путь для расширения жизни на сушу.Хотя GOE способствовало эволюционным инновациям, оно также ввело окислительный стресс и вызвало вымирание многих анаэробных организмов. Тем не менее, появление кислородного фотосинтеза остаётся одним из самых значимых эволюционных достижений в истории Земли.

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

JoVE Core

Microbiology

Микробиология

Unit

Единица

Microbial Evolution

Микробная эволюция

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

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.

How Photosynthesis Changed Earth | JoVE K12

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9-12.EVS.3.5

How Photosynthesis Changed Earth

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