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

La fotosíntesis, el proceso por el cual los organismos fotosintéticos convierten la energía lumínica en energía química, probablemente comenzó hace unos 3.500 millones de años.La forma más temprana de fotosíntesis probablemente fue anoxigénica, utilizando varios donantes alternativos de electrones, como sulfuro de hidrógeno o hierro ferroso, y liberando azufre o hierro oxidado en lugar de oxígeno.Más tarde, las cianobacterias desarrollaron la capacidad de realizar la fotosíntesis oxigénica utilizando agua como donante de electrones y liberando oxígeno como subproducto.El oxígeno liberado por las cianobacterias reaccionó con el hierro disuelto en los océanos, formando óxidos de hierro insolubles que se depositaron como formaciones de hierro en bandas en el fondo marino.Mientras tanto, las cianobacterias formaron esteras microbianas estratificadas, que finalmente se fosilizaron en estromatolitos.A medida que la mayor parte del hierro disuelto del océano se oxidaba y los principales sumideros de ogénito en los océanos se saturaban cada vez más, el oxígeno libre finalmente pudo acumularse en la atmósfera.Este aumento del oxígeno atmosférico desencadenó el Gran Evento de Oxidación hace unos 2.400 millones de años, permitiendo el metabolismo aeróbico y la formación de la capa de ozono.

origen de la fotosíntesis

La fotosíntesis representa un proceso biológico fundamental que transformó la atmósfera terrestre y allanó el camino para la vida compleja. Surgiendo hace aproximadamente entre 3,4 y 3,8 mil millones de años, los primeros organismos fotosintéticos aprovecharon la energía lumínica para producir compuestos orgánicos. Estos fototróficos anioxigénicos utilizaban donadores de electrones como sulfuro de hidrógeno (H₂S) o hierro ferroso (Fe²⁺), en lugar de agua, y no liberaban osígeno molecular (O₂) como subproducto. Diversos grupos, incluyendo el azufre verde y las bacterias púrpuras, contribuyeron a esta temprana diversidad fototrófica.Un hito evolutivo importante fue el desarrollo de la fotosíntesis oxigénica por cianobacterias. Estos microorganismos utilizaban el agua como donante de electrones, produciendo osígeno molecular como subproducto. Las cianobacterias colonizaron ambientes marinos poco profundos, formando extensas esteras microbianas. Con el tiempo, estas esteras acumularon sedimentos y precipitados, fosilizándose en estromatolitos, algunas de las evidencias más antiguas conocidas de vida. A medida que los niveles de oxígeno aumentaban localmente, reaccionaba con abundante hierro disuelto en el agua de mar, precipitándose como óxidos de hierro. Estos óxidos se depositaron en el fondo marino, generando formaciones de hierro en bandas (BIFs), que sirven como marcadores geológicos clave del cambio atmosférico temprano.Una vez que la mayor parte del hierro oceánico había sido oxidada, el exceso de oxígeno comenzó a difundirse en la atmósfera, desencadenando el Gran Evento de Oxidación (GOE) hace unos 2.400 millones de años. Esta transición alteró drásticamente la química y la biología de la Tierra. El aumento del oxígeno atmosférico permitió la evolución de la respiración aeróbica, que proporciona mucha más energía que el metabolismo anaeróbico. También condujo a la formación de la capa de ozono estratosférico (O₃), protegiendo al planeta de la dañina radiación ultravioleta y allanando el camino para que la vida se expandiera hacia la tierra.Aunque el GOE promovió la innovación evolutiva, también introdujo estrés oxidativo y causó la extinción de muchos organismos anaeróbicos. No obstante, la llegada de la fotosíntesis oxigénica sigue siendo uno de los desarrollos evolutivos más significativos en la historia de la Tierra.

Origen de la fotosíntesis

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

Educación

JoVE Core

Microbiology

Microbiología

Unit

Unidad

Microbial Evolution

Evolución microbiana

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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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