Review the Equation for the Breakdown of Atp and the Release of Energy Shown Below
ATP: Adenosine Triphosphate
Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions to harness the energy within the bonds of ATP.
Learning Objectives
Explicate the role of ATP every bit the currency of cellular energy
Key Takeaways
Key Points
- Adenosine triphosphate is composed of the nitrogenous base adenine, the five-carbon sugar ribose, and three phosphate groups.
- ATP is hydrolyzed to ADP in the reaction ATP+H2O→ADP+Pi+ gratis energy; the calculated ∆G for the hydrolysis of ane mole of ATP is -57 kJ/mol.
- ADP is combined with a phosphate to form ATP in the reaction ADP+Pi+gratis free energy→ATP+H2o.
- The free energy released from the hydrolysis of ATP into ADP is used to perform cellular work, usually past coupling the exergonic reaction of ATP hydrolysis with endergonic reactions.
- Sodium-potassium pumps apply the energy derived from exergonic ATP hydrolysis to pump sodium and potassium ions across the cell membrane while phosphorylation drives the endergonic reaction.
Fundamental Terms
- energy coupling: Energy coupling occurs when the energy produced by one reaction or system is used to drive some other reaction or system.
- endergonic: Describing a reaction that absorbs (rut) energy from its environment.
- exergonic: Describing a reaction that releases free energy (heat) into its environment.
- free energy: Gibbs gratis energy is a thermodynamic potential that measures the useful or process-initiating work obtainable from a thermodynamic organisation at a constant temperature and pressure (isothermal, isobaric).
- hydrolysis: A chemic process of decomposition involving the splitting of a bond by the addition of water.
ATP: Adenosine Triphosphate
Adenosine triphosphate (ATP) is the energy currency for cellular processes. ATP provides the free energy for both energy-consuming endergonic reactions and energy-releasing exergonic reactions, which require a small input of activation energy. When the chemic bonds inside ATP are broken, free energy is released and tin be harnessed for cellular piece of work. The more than bonds in a molecule, the more than potential free energy it contains. Because the bond in ATP is so easily broken and reformed, ATP is like a rechargeable battery that powers cellular procedure ranging from DNA replication to protein synthesis.
Molecular Construction
Adenosine triphosphate (ATP) is comprised of the molecule adenosine bound to three phosphate groups. Adenosine is a nucleoside consisting of the nitrogenous base of operations adenine and the v-carbon sugar ribose. The 3 phosphate groups, in guild of closest to furthest from the ribose sugar, are labeled alpha, beta, and gamma. Together, these chemical groups constitute an energy powerhouse. The two bonds between the phosphates are equal high-energy bonds (phosphoanhydride bonds) that, when broken, release sufficient energy to power a variety of cellular reactions and processes. The bond between the beta and gamma phosphate is considered "loftier-energy" because when the bond breaks, the products [adenosine diphosphate (ADP) and one inorganic phosphate group (Pi)] have a lower free energy than the reactants (ATP and a water molecule). ATP breakdown into ADP and Pi is called hydrolysis because it consumes a water molecule (hydro-, meaning "water", and lysis, pregnant "separation").
Adenosine Triphosphate (ATP): ATP is the primary energy currency of the cell. It has an adenosine courage with 3 phosphate groups attached.
ATP Hydrolysis and Synthesis
ATP is hydrolyzed into ADP in the following reaction:
ATP+HtwoO→ADP+Pi+energy
Like most chemical reactions, the hydrolysis of ATP to ADP is reversible. The opposite reaction combines ADP + Pi to regenerate ATP from ADP. Since ATP hydrolysis releases energy, ATP synthesis must require an input of free free energy.
ADP is combined with a phosphate to form ATP in the following reaction:
ADP+Pi+gratis energy→ATP+H2O
ATP and Energy Coupling
Exactly how much gratis energy (∆M) is released with the hydrolysis of ATP, and how is that free free energy used to do cellular piece of work? The calculated ∆Yard for the hydrolysis of one mole of ATP into ADP and Pi is −seven.3 kcal/mole (−30.5 kJ/mol). All the same, this is simply true nether standard weather, and the ∆Thou for the hydrolysis of one mole of ATP in a living prison cell is nearly double the value at standard conditions: xiv kcal/mol (−57 kJ/mol).
ATP is a highly unstable molecule. Unless quickly used to perform piece of work, ATP spontaneously dissociates into ADP + Pi, and the free free energy released during this process is lost every bit estrus. To harness the energy inside the bonds of ATP, cells use a strategy called energy coupling.
Energy Coupling in Sodium-Potassium Pumps
Energy Coupling: Sodium-potassium pumps use the energy derived from exergonic ATP hydrolysis to pump sodium and potassium ions across the cell membrane.
Cells couple the exergonic reaction of ATP hydrolysis with the endergonic reactions of cellular processes. For instance, transmembrane ion pumps in nerve cells employ the energy from ATP to pump ions beyond the cell membrane and generate an action potential. The sodium-potassium pump (Na+/G+ pump) drives sodium out of the cell and potassium into the cell. When ATP is hydrolyzed, it transfers its gamma phosphate to the pump protein in a process chosen phosphorylation. The Na+/One thousand+ pump gains the free energy and undergoes a conformational change, allowing it to release 3 Na+ to the outside of the cell. Two extracellular Thousand+ ions bind to the poly peptide, causing the protein to change shape again and discharge the phosphate. By donating free energy to the Na+/1000+ pump, phosphorylation drives the endergonic reaction.
Free energy Coupling in Metabolism
During cellular metabolic reactions, or the synthesis and breakup of nutrients, certain molecules must exist altered slightly in their conformation to get substrates for the next stride in the reaction series. In the very first steps of cellular respiration, glucose is broken down through the process of glycolysis. ATP is required for the phosphorylation of glucose, creating a high-energy but unstable intermediate. This phosphorylation reaction causes a conformational change that allows enzymes to catechumen the phosphorylated glucose molecule to the phosphorylated sugar fructose. Fructose is a necessary intermediate for glycolysis to move forward. In this case, the exergonic reaction of ATP hydrolysis is coupled with the endergonic reaction of converting glucose for use in the metabolic pathway.
Source: https://courses.lumenlearning.com/boundless-biology/chapter/atp-adenosine-triphosphate/