During the course of the origin of life, anoxygenic...

Name: Problem 4, Chapter 17: Evolutionary Analysis: Global Edition
Uploaded: 2020-07-27T01:16:46-08:00
Duration: 1 min 24 s
Channel: Courtney Burson
Description: During the course of the origin of life, anoxygenic photosynthetic organisms appeared earlier on Earth. These did not liberate oxygen. They were followed by oxygenic photosynthetic organisms, which liberated oxygen as a byproduct of photosynthesis. What was the effect of oxygenic photosynthetic organisms on the development of advanced eukaryotes?

During the course of the origin of life, anoxygenic photosynthetic organisms appeared earlier on Earth. These did not liberate oxygen. They were followed by oxygenic photosynthetic organisms, which liberated oxygen as a byproduct of photosynthesis. What was the effect of oxygenic photosynthetic organisms on the development of advanced eukaryotes?

Key Concepts

Aerobic Respiration

Aerobic respiration is the metabolic process by which cells use oxygen to efficiently extract energy from organic molecules. The presence of atmospheric oxygen allowed organisms to develop and harness this process, leading to significant increases in energy yield compared to anaerobic processes. This energy efficiency was essential in supporting the complexity and size of advanced eukaryotic cells.

Evolution of Eukaryotes and Endosymbiosis

The rise in atmospheric oxygen contributed to the evolution of advanced eukaryotes by fostering the development of energy-demanding cellular structures and functions. It also created favorable conditions for endosymbiotic events, such as the incorporation of aerobic prokaryotes as mitochondria within host cells, a key step that allowed eukaryotes to exploit aerobic respiration and evolve greater cellular complexity.

Oxygenic Photosynthesis

This is the process through which certain organisms convert light energy into chemical energy while splitting water molecules, resulting in the release of oxygen as a byproduct. It marked a critical turning point in Earth's history, fundamentally altering the chemical composition of the atmosphere and setting the stage for complex life forms.

Atmospheric Oxygenation (Great Oxygenation Event)

The gradual accumulation of oxygen in Earth’s atmosphere, often referred to as the Great Oxygenation Event, was a transformative period that resulted from the activity of oxygenic photosynthesizers. This increase in oxygen not only changed the planet’s redox state but also imposed new selective pressures on existing organisms, paving the way for the evolution of species capable of exploiting aerobic metabolism.

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