Examples of energy coupling in the following topics:
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- Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions to harness the energy within the bonds of ATP.
- ATP provides the energy for both energy-consuming endergonic reactions and energy-releasing exergonic reactions, which require a small input of activation energy.
- To harness the energy within the bonds of ATP, cells use a strategy called energy coupling.
- Cells couple the exergonic reaction of ATP hydrolysis with the endergonic reactions of cellular processes.
- In this example, the exergonic reaction of ATP hydrolysis is coupled with the endergonic reaction of converting glucose for use in the metabolic pathway.
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- Activation energy is the energy required for a reaction to occur, and determines its rate.
- Since these are energy-storing bonds, they release energy when broken.
- Cells will at times couple an exergonic reaction $(\Delta G<0)$ with endergonic reactions $(\Delta G>0)$, allowing them to proceed.
- This spontaneous shift from one reaction to another is called energy coupling.
- One example of energy coupling using ATP involves a transmembrane ion pump that is extremely important for cellular function.
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- Anabolic reactions require energy.
- Cells can combine anabolic reactions with catabolic reactions that release energy to form an efficient energy cycle.
- ATP, a high energy molecule, couples anabolism by the release of free energy.
- Anabolism requires the input of energy, described as an energy intake ("uphill") process.
- Catabolism is a "downhill" process where energy is released as the organism uses up energy.
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- Radical coupling (recombination) reactions are very fast, having activation energies near zero.
- Consequently, if short lived radicals are to contribute to useful synthetic procedures by way of a radical coupling, all the events leading up to the coupling must take place in a solvent cage.
- If oxygen is present, it bonds to the carbon radical before the •NO coupling occurs.
- The first diagram below shows two such coupling reactions.
- The third diagram shows a mechanism for the phenol coupling.
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- Bacteriorhodopsin acts a proton pump, generating cellular energy in a manner independent of chlorophyll.
- The resulting proton gradient is subsequently converted into chemical energy.
- The resulting proton gradient is subsequently converted into chemical energy.
- Last, chlorophyll-based phototrophy is coupled to carbon fixation (the incorporation of carbon dioxide into larger organic molecules) and for that reason is photosynthesis, which is not true for bacteriorhodopsin-based system.
- Chemiosmotic coupling between sun energy, bacteriorhodopsin and phosphorylation by ATP synthase (chemical energy) during photosynthesis in Halobacterium salinarum (syn.
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- A living cell cannot store significant amounts of free energy.
- Rather, a cell must be able to handle that energy in a way that enables the cell to store energy safely and release it for use as needed.
- ATP is often called the "energy currency" of the cell and can be used to fill any energy need of the cell.
- The addition of a phosphate group to a molecule requires energy.
- The energy from ATP can also be used to drive chemical reactions by coupling ATP hydrolysis with another reaction process in an enzyme.
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- Alternative and renewable energy sources can reduce the environmental impact of energy production and consumption.
- Renewable energy is energy that comes from natural resources, such as sunlight, wind, rain, tides, waves, and geothermal heat, which are all naturally replenished.
- While many renewable energy projects are large-scale, renewable technologies can also be suited to rural and remote areas, where energy is often crucial in human development.
- Climate change concerns, coupled with high oil prices, peak oil, and increasing government support, are driving more and more renewable energy legislation, incentives and commercialization.
- Ethanol is a quasi-renewable energy source.
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- For instance, the heart rate will increase, pupils will dilate, energy will be mobilized, and blood flow will be diverted from other nonessential organs to skeletal muscle.
- There are two main groups of adrenergic receptors, α and β, with several subtypes. α receptors have the subtypes α1 (a Gq coupled receptor) and α2 (a Gi coupled receptor).
- All three are linked to Gs proteins (although β2 also couples to Gi), which in turn are linked to adenylate cyclase.
- α1-adrenergic receptors are members of the G protein-coupled receptor superfamily.
- Adrenaline and noradrenaline are ligands to α1, α2, or β-adrenergic receptors. α1 receptors couple to Gq, resulting in increased intracellular Ca2+ and causing smooth muscle contraction. α2 receptors couple to Gi, causing a decrease in cAMP activity and resulting in smooth muscle contraction. β receptors couple to Gs, increasing intracellular cAMP activity and resulting in heart muscle contraction, smooth muscle relaxation and glycogenolysis.
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- A radiation detector is a device used to detect, track, or identify high-energy particles.
- Modern detectors are also used as calorimeters to measure the energy of detected radiation.
- If a particle has enough energy to ionize a gas atom or molecule, the resulting electrons and ions cause a current flow, which can be measured.
- A scintillation detector is created by coupling a scintillator -- a material that exhibits luminescence when excited by ionizing radiation -- to an electronic light sensor, such as a photomultiplier tube (PMT) or a photodiode.
- Scintillators can also be used in neutron and high-energy particle physics experiments, new energy resource exploration, x-ray security, nuclear cameras, computed tomography, and gas exploration.
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- ‘We've gone from every-other-day pickups to once every couple of weeks,' says Kelley Losey, an environmental services manager at the company.
- Making paper from recycled materials uses 70% less energy and produces 73% less air pollution compared with making paper from virgin raw materials.
- Recycling a plastic bottle saves enough energy to power a 60 watt light bulb for three hours.
- A recycled glass bottle saves the amount of energy needed to power a computer for 25 minutes.
- Manufacturing aluminium from scrap requires up to 95% less energy than producing it from scratch.