ATP-ADP cycle

• One must have a constant supply of energy to perform tasks daily.
• The energy used to execute tasks sometimes gets exhausted, requiring constant replenishment for cells to function optimally.
• When ATP transfers a phosphate group to another substance, it undergoes changes in its chemical composition.
• The chemical composition and functions of adenosine triphosphate are discussed on page 29.
• To regain energy in the form of ATP, healthful and nutritious food is consumed, which can be oxidized to release energy.
• Having a constant supply of energy makes cells function at optimum for maintenance and survival.
• Cells regenerate the energy they constantly need through the ADP-ATP cycle, which is an alternation between endergonic and exergonic reactions.
• The energy from processes that release energy is transferred to processes that consume energy in the ADP-ATP cycle.
• Combining ADP and a phosphate group requires energy in the ADP-ATP cycle.
• Recharging a used battery to replenish the utilized electrical potential requires energy in the ADP-ATP cycle.
• The process of hydrolysis releases energy to drive various biological processes in the ADP-ATP cycle.
• A battery is drained when it is used in flashcards and other electrical devices to perform work.
• Reaction coupling lowers the energy cost of cellular processes.
• Each of these phosphate groups is negatively charged, which makes them repel each other.
• Adenosine triphosphate is unstable and has high potential energy.
• ATP carries energy between exergonic reactions and endergonic reactions.
• The transfer of a phosphate group to a molecular is called phosphorylation, which is essential in energizing ADP to synthesize ATP or another molecular intermediate.
• The endergonic nature of sucrose synthesis is represented by a positive Gibbs free energy (i.e., +27 kJ/mol).
• The triphosphate tail is the portion of ATP that provides energy for cellular work.
• ATP hydrolysis is exergonic, thus the Gibbs free energy will be negative (i.e., −30 kJ/mol).
• ATP hydrolysis releases previously stored energy, which allows the change in free energy to perform various cellular processes.
• Adenosine triphosphate is a nucleotide composed of nitrogen-containing base adenine, five-carbon sugar ribose and three phosphate groups.
• The crowding of negative charges in the triphosphate tail contributes to the potential energy of ATP.
• By coupling these two reactions, the energy released from the conversion of ATP to ADP is channeled into an energy-demanding reaction.
• ADP has almost the same structural components as the ATP, but ADP has only two phosphate groups instead of three.
• High-energy bonds link these phosphate groups together.