Examples of free radical in the following topics:
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- Reactive oxygen species (ROS), such as peroxides and free radicals, are the highly-reactive products of many normal cellular processes, including the mitochondrial reactions that produce ATP and oxygen metabolism.
- Examples of ROS include the hydroxyl radical OH, H2O2, and superoxide (O−2).
- Free radicals are reactive because they contain free unpaired electrons; they can easily oxidize other molecules throughout the cell, causing cellular damage and even cell death.
- Free radicals are thought to play a role in many destructive processes in the body, from cancer to coronary artery disease.
- Peroxisomes oversee reactions that neutralize free radicals.
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- Melatonin is an effective antioxidant, protecting the CNS from free radicals such as nitric oxide and hydrogen peroxide.
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- Free energy, called Gibbs free energy (G), is usable energy or energy that is available to do work.
- A measurement of free energy is used to quantitate these energy transfers.
- Free energy is called Gibbs free energy (G) after Josiah Willard Gibbs, the scientist who developed the measurement.
- A negative ∆G also means that the products of the reaction have less free energy than the reactants because they gave off some free energy during the reaction.
- In this case, the products have more free energy than the reactants.
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- Under some conditions, selection occurs quickly or radically.
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- Since ATP hydrolysis releases energy, ATP synthesis must require an input of free energy.
- Exactly how much free energy (∆G) is released with the hydrolysis of ATP, and how is that free energy used to do cellular work?
- Unless quickly used to perform work, ATP spontaneously dissociates into ADP + Pi, and the free energy released during this process is lost as heat.
- The Na+/K+ pump gains the free energy and undergoes a conformational change, allowing it to release three Na+ to the outside of the cell.
- By donating free energy to the Na+/K+ pump, phosphorylation drives the endergonic reaction.
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- This hypothesis, proposed first in 1980, was a radical explanation based on a sharp spike in the levels of iridium (which rains down from space in meteors at a fairly constant rate, but is otherwise absent on earth's surface) at the rock stratum that marks the boundary between the Cretaceous and Paleogene periods .
- It was a radical explanation, but the report of an appropriately aged and sized impact crater in 1991 made the hypothesis more credible.
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- Scyphozoans are free-swimming, polymorphic, dioecious, and carnivorous cnidarians with a prominent medusa morphology.
- Scyphozoans live most of their life cycle as free-swimming, solitary carnivores.
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- Mitochondria are energy-producing organelles that are thought to have once been a type of free-living alpha-proteobacterium.
- As the amount of oxygen increased in the atmosphere billions of years ago and as successful aerobic prokaryotes evolved, evidence suggests that an ancestral cell with some membrane compartmentalization engulfed a free-living aerobic prokaryote, specifically an alpha-proteobacterium, thereby giving the host cell the ability to use oxygen to release energy stored in nutrients.
- Alpha-proteobacteria are a large group of bacteria that includes species symbiotic with plants, disease organisms that can infect humans via ticks, and many free-living species that use light for energy.
- These features all support that mitochondria were once free-living prokaryotes.
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- In soil, members of the genus Clostridium are examples of free-living, nitrogen-fixing bacteria.
- Symbionts may fix more nitrogen in soils than free-living organisms by a factor of 10.
- Nitrogenase, the enzyme that fixes nitrogen, is inactivated by oxygen, so the nodule provides an oxygen-free area for nitrogen fixation to take place.
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- ATP is critical for muscle contractions because it breaks the myosin-actin cross-bridge, freeing the myosin for the next contraction.