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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- 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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- Unlike in primary active transport, in secondary active transport, ATP is not directly coupled to the molecule of interest.
- While this process still consumes ATP to generate that gradient, the energy is not directly used to move the molecule across the membrane, hence it is known as secondary active transport.
- This secondary process is also used to store high-energy hydrogen ions in the mitochondria of plant and animal cells for the production of ATP.
- The potential energy that accumulates in the stored hydrogen ions is translated into kinetic energy as the ions surge through the channel protein ATP synthase, and that energy is used to convert ADP into ATP.
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- The various types of energy include kinetic, potential, and chemical energy.
- The potential energy stored in molecules can be converted to chemical energy, which can ultimately be converted to kinetic energy, enabling an organism to move.
- Energy associated with objects in motion is called kinetic energy.
- The jet engines are converting potential energy in fuel to the kinetic energy of movement.
- This type of potential energy is called chemical energy, and like all potential energy, it can be used to do work.
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- The citrate will then harvest the remainder of the extractable energy from what began as a glucose molecule and continue through the citric acid cycle.
- For each acetyl CoA that enters the citric acid cycle, two carbon dioxide molecules are released in reactions that are coupled with the production of NADH molecules from the reduction of NAD+ molecules.
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- All organisms require energy to complete tasks; metabolism is the set of the chemical reactions that release energy for cellular processes.
- Plants convert light energy from the sun into chemical energy stored in molecules during the process of photosynthesis.
- Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed.
- Energy is needed to perform heavy labor and exercise, but humans also use a great deal of energy while thinking and even while sleeping.
- Just as energy is required to both build and demolish a building, energy is required for both the synthesis and breakdown of molecules.
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- Free energy, called Gibbs free energy (G), is usable energy or energy that is available to do work.
- Since chemical reactions release energy when energy-storing bonds are broken, how is the energy associated with chemical reactions quantified and expressed?
- A measurement of free energy is used to quantitate these energy transfers.
- In other words, Gibbs free energy is usable energy or energy that is available to do work.
- Exergonic reactions release energy; endergonic reactions require energy to proceed.
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- Plants need an energy source to grow.
- This is coupled to the uptake of sucrose with a carrier protein called the sucrose-H+ symporter.
- They assist with metabolic activities and produce energy for the STEs .
- Neighboring companion cells carry out metabolic functions for the sieve-tube elements and provide them with energy.
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- Protists that store energy by photosynthesis belong to a group of photoautotrophs and are characterized by the presence of chloroplasts.
- Protists accomplish phototaxis, movement toward light, by coupling their locomotion strategy with a light-sensing organ.