ATP

• plants need energy for things like active transport (e.g. to transport solutes from the leaves), DNA replication and cell division and protein synth
• animals need energy for things like active transport (e.g. to absorb glucose from the ileum epithelium into the bloodstream), DNA replication, cell division and protein synth
• plant and animal cells release energy from glucose - this process is called respiration. A cell cannot get its energy directly from glucose. So in resp, the energy released from glucose is used to make ATP
• ATP = adenosine triphosphate, a molecule that stores energy in the form of chemical bonds
• ATP is made from the nucleotide base adenine, combined with a ribose sugar and three phosphate groups. It is what is known as a nucleotide derivative bc it is a modified form of a nucleotide
• Once made, ATP diffuses the the part of the cell that needs energy. The energy in ATP is stored in high energy bonds between the phosphate groups. It is released via hydrolysis reactions
• when energy is needed by a cell, ATP is broken down into ADP (adenosine diphosphate) and Pi (inorganic phosphate) (a single phosphate). This is a hydrolysis reaction. A phosphate bond is broken and energy is released. The reaction is catalysed by the enzyme ATP hydrolase
• ATP hydrolysis can be 'coupled' to other energy-requiring reactions in the cell - this means the energy released can be used directly to make the coupled reaction happen rather than being lost as heat
• the released inorganic phosphate can also be put to use - it can be added to another compound (phosphorylation), which often makes the compound more reactive
• ATP can be resynthesised in a condensation reaction between ADP and Pi. This happens during both respiration and photosynthesis, and is catalysed by the enzyme ATP synthase
• ATP is not energy - it is a store of energy

  energy is used to make ATP

  then it is released when ATP is hydrolysed to ADP and Pi