ATP in a Molecule Energy is needed for: Active transport Cell division Movement of cilia and flagella Production and storage of proteins ATP – adenosine triphosphate • Quick energy for any organelle in a cell that needs it • Energy is stored in the chemical bonds of this molecule • Made up of: 1. adenosine molecule (adenine + ribose) 2. 3 phosphate groups Figure 6.8 The structure and hydrolysis of ATP • ATP is a nucleotide that performs many essential roles in the cell. • It is the major energy currency of the cell, providing the energy for most of the energy-consuming activities of the cell. • It is one of the monomers used in the synthesis of RNA and, after conversion to deoxyATP (dATP), DNA. • It regulates many biochemical pathways. Energy • When the third phosphate group of ATP is removed by hydrolysis, a substantial amount of free energy is released. • ATP + H2O ADP + Pi • ADP is adenosine diphosphate. Pi is inorganic phosphate. • For this reason, this bond is known as a "high-energy" bond and is depicted in the figure by a wavy red line. Dehydration synthesis hooks new phosphates on (takes energy to make bond) AMP ADP ATP Hydrolysis removes ONE Phosphate and releases energy ADP ATP Pg 101 How do cells use the energy of ATP? • ATP is a small compound • Cellular proteins have a specific site where ATP can bind; thus, when the last bond in ATP is broken and the energy is released, the cell can use the energy Ex. Active transport, making proteins, etc. • ATP is like a battery – it represents stored energy, and must “fit” into correct area to access that energy 2 major processes that deal with the use/production of ATP: • Photosynthesis – conversion of light energy to chemical energy (sugar); this sugar can then be used through the process of • Cellular respiration – breakdown of sugar to produce ATP (~38 ATP produced per glucose) The equations… • Photosynthesis: (in chloroplasts) light 6H20 + 6CO2 + 38 ATP C6H12O6 + 6O2 enzymes • Cellular respiration: (in mitochondria) C6H12O6 + 6O2 + 38 ADP + 38Pi 6CO2 + 6H20 + 38ATP Types of reactions based on energy transformations… • In any chemical reaction, bonds are either formed or broken. • Since bonds are a form of energy, all reactions result in either the absorption or release of energy. • Exergonic reactions are ones that release energy; here, bonds are broken – cellular respiration is this! • Endergonic reactions absorb energy to form bonds – photosynthesis is this!