Great Oxidation Event
Great Oxidation Event - Related Videos
03:14
Oxidation Numbers
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2020
In redox reactions, the transfer of electrons occurs between reacting species. Electron transfer is described by a hypothetical number called the oxidation number (or oxidation state). It represents the effective charge of an atom or element, which is assigned using a set of rules. Oxidation Number (Oxidation State) In the case of an ionic compound, oxidation numbers are assigned based on the number of electrons transferred between reacting species. For example, in the formation of calcium...
01:15
Pyruvate Oxidation
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2019
After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure that pyruvate can enter the next metabolic pathway so that energy stored in the pyruvate molecules can be harnessed by the cells. First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
14:33
Event-related Potentials and the Oddball Task
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2023
Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel—University of Southern California Given the overwhelming amount of information captured by the sensory organs, it is crucial that the brain is able to prioritize the processing of certain stimuli, to spend less effort on what might not be currently important and to attend to what is. One heuristic the brain uses is to ignore stimuli that are frequent or constant in favor of stimuli that are unexpected or unique. Therefore, rare events...
03:11
Oxidation-Reduction Reactions
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2020
Oxidation–Reduction Reactions Earth’s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential role in the metabolism of aerobic organisms and in many environmental processes that shape the world. The term oxidation was originally used to describe chemical reactions involving O2, but its meaning has evolved to refer to a broad and important reaction class known as oxidation–reduction (redox) reactions. Some redox reactions involve the transfer of...
09:00
Live Cell Imaging of Early Autophagy Events: Omegasomes and Beyond
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Cited by 13 •
2013
Time-lapse microscopy of fluorescently labeled autophagy markers allows monitoring of the dynamic autophagy response with high temporal resolution. Using specific autophagy and organelle markers in a combination of 3 different colors, we can follow the contribution of a protein to autophagosome formation in a robust spatial and temporal context.
FAQs
Cyanobacteria released oxygen as a product of oxygenic photosynthesis, but that oxygen did not immediately accumulate freely. It first reacted with dissolved iron, sulfur compounds, and other chemical sinks in the oceans and atmosphere. As those sinks became less effective, a greater share of biologically produced oxygen remained available to alter environmental chemistry.
Iron, sulfur compounds, and other sinks acted as chemical consumers of oxygen. Their reactions temporarily buffered the effects of oxygen production, keeping atmospheric and oceanic levels low despite continued release by cyanobacteria. The eventual reduction in sink effectiveness marked an important change in oxygen balance, allowing accumulation to influence marine conditions and biological processes.
Greater oxygen availability made aerobic respiration possible on a much broader environmental scale. The overview identifies this pathway as energy-rich, so its expansion changed the energetic possibilities for cells and ecosystems. At the same time, organisms dependent on oxygen-free conditions faced environmental disruption, making oxygen availability a major ecological contrast between aerobic and anaerobic life.
As oxygen accumulated in marine environments, many anaerobic organisms, which rely on oxygen-free conditions, were lost. This was not simply a change in atmospheric composition; it altered the chemical setting in which entire communities lived. The biological consequence was a major restructuring of marine ecosystems, with oxygen tolerance becoming increasingly important.
It provides a geological and biological context for the spread of energy-rich aerobic respiration. By changing oxygen availability, the event altered which cellular energy strategies were possible and helped reshape the conditions surrounding cellular evolution. Researchers therefore use it to connect planetary chemistry with biological change rather than treating cellular evolution as an isolated cellular process.
The event shows that biological activity can produce environmental changes that reorganize ecosystems on a planetary scale. Oxygen released by cyanobacteria changed marine chemistry, affected anaerobic organisms, and enabled aerobic respiration. In biology, this makes the event a framework for understanding how ecological transformation and cellular energy innovations contributed to the later diversification of complex life.