how adenosine triphosphate is the ‘energy currency’ of cells? Is the molecule structured to trap and transfer energy or create it?
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ATP stores in the cell aren’t enough to last the cell very long- it handles long-term energy storage differently. ATP is a useful energy transfer molecule because it’s moderately stable and moderately energetic. It’s not too hard for the cell to break the ATP energy-holding bonds, but it won’t go off on its own either. It holds enough energy to be useful, but it won’t like blow up the cell either. It’s a nice predictable Goldilocks system to carry the energy for one* chemical reaction or movement at a time.
ATP stores in the cell aren’t enough to last the cell very long- it handles long-term energy storage differently. ATP is a useful energy transfer molecule because it’s moderately stable and moderately energetic. It’s not too hard for the cell to break the ATP energy-holding bonds, but it won’t go off on its own either. It holds enough energy to be useful, but it won’t like blow up the cell either. It’s a nice predictable Goldilocks system to carry the energy for one* chemical reaction or movement at a time.
Remember in chemistry where some reactions are endothermic and others are exothermic? One requires energy to make the reaction happen and the other gives off energy when a reaction happens? (Fire is exothermic, a bunch of heat comes out when you burn wood. A tree growing is endothermic. It takes energy from the sun to slowly assemble wood fibers and build up the wood.)
ATP is a molecule capable of reversible reactions. When you eat, your body uses the food energy to assemble the ATP molecule into a high energy state. When your cell gets that ATP molecule, it can reverse that reaction extracting the energy.
Remember in chemistry where some reactions are endothermic and others are exothermic? One requires energy to make the reaction happen and the other gives off energy when a reaction happens? (Fire is exothermic, a bunch of heat comes out when you burn wood. A tree growing is endothermic. It takes energy from the sun to slowly assemble wood fibers and build up the wood.)
ATP is a molecule capable of reversible reactions. When you eat, your body uses the food energy to assemble the ATP molecule into a high energy state. When your cell gets that ATP molecule, it can reverse that reaction extracting the energy.
Chemical bonds with more energy in them are weaker, less stable. This energy in bonds, referred to as ‘chemical energy’, is a kind of potential energy; think of a ball sitting at the top of a hill, ready to roll down. Stronger bonds have less potential energy in them, so they are like the ball sitting at the bottom of the hill. If you run a chemical reaction in which these weaker bonds are broken and stronger bonds are formed, then you are effectively rolling the ball down the hill, converting potential energy to kinetic energy in the form of heat. The heat energy released by such reactions is the energy contribution to the cell from the breakdown of molecules like ATP, which have relatively weak bonds with high potential energy, hence their role as energy storage.
You can also think about the formation of ATP as storing potential energy by pushing the ball back up to the top of the hill; breaking stronger bonds and forming weaker ones.
Disclaimer: This articulation of bond strength is a simplification which is complicated by hetero vs homolytic bond breaking and the varying electronegativities of atoms among which electrons are being exchanged.
Chemical bonds with more energy in them are weaker, less stable. This energy in bonds, referred to as ‘chemical energy’, is a kind of potential energy; think of a ball sitting at the top of a hill, ready to roll down. Stronger bonds have less potential energy in them, so they are like the ball sitting at the bottom of the hill. If you run a chemical reaction in which these weaker bonds are broken and stronger bonds are formed, then you are effectively rolling the ball down the hill, converting potential energy to kinetic energy in the form of heat. The heat energy released by such reactions is the energy contribution to the cell from the breakdown of molecules like ATP, which have relatively weak bonds with high potential energy, hence their role as energy storage.
You can also think about the formation of ATP as storing potential energy by pushing the ball back up to the top of the hill; breaking stronger bonds and forming weaker ones.
Disclaimer: This articulation of bond strength is a simplification which is complicated by hetero vs homolytic bond breaking and the varying electronegativities of atoms among which electrons are being exchanged.
It holds energy. When a cell turns glucose into CO2 and water, that releases energy. The cell doesn’t necessarily need that energy right then and there, so the cell takes adenosine diphosphate and adds another phosphate to it by using that energy from the sugar. This creates adenosine triphosphate, which the cell can move somewhere else to be used, at which point the cell breaks it back down into adenosine diphosphate, releasing that stored energy.
It holds energy. When a cell turns glucose into CO2 and water, that releases energy. The cell doesn’t necessarily need that energy right then and there, so the cell takes adenosine diphosphate and adds another phosphate to it by using that energy from the sugar. This creates adenosine triphosphate, which the cell can move somewhere else to be used, at which point the cell breaks it back down into adenosine diphosphate, releasing that stored energy.
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