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HB 3.A.1 ATP and ADP Cycle. Develop and use models to explain how chemical reactions among ATP, ADP and inorganic phosphate act to transfer chemical energy within cells. What are ATP and ADP?. ATP - adenosine triphosphate supplies energy to the cell the most important biological molecule
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HB 3.A.1 ATP and ADP Cycle Develop and use models to explain how chemical reactions among ATP, ADP and inorganic phosphate act to transfer chemical energy within cells
What are ATP and ADP? • ATP-adenosine triphosphate supplies energy to the cell • the most important biological molecule • ATP is composed of three parts • A nitrogenous base (adenine) • A sugar (ribose) • Three phosphate groups bonded by “high energy bonds” • ADP is adenosine diphosphate and is the spent molecule of ATP • Has two phosphate groups and a lot less energy
ATP-ADP Cycle • Cells break phosphate bonds to supply energy to carry out most cellular functions converting ATP into ADP and a phosphate available for reuse • When any phosphate bonds are broken, or formed energy is involved • When a phosphate is removed from ATP energy is released • Energy is used when a phosphate bonds to the molecule • ADP is recycled back into ATP • Because ADP has less energy than ATP
The steps to the ATP-ADP cycle • ATP is broken to supply cells with high amounts of energy • ADP is formed and released back into the cytoplasm ATP ADP + phosphate group + energy • When the cell needs more energy a phosphate attaches to ADP to form ATP the energy used to attach the free phosphate is about the same as energy given off by the breaking of the phosphate bond in ATP ADP + phosphate + energy ATP