2.3: Energy and ATP

Adeneine- nitrogen containing organism base
ribose- pentose sugar
3 phosphate groups
joined by phosphodiester bonds

phosphodiester bonds have a low activation energy so are easily hydrolysed which releases energy

ATP hydrolysed to ADP and Pi by ATPase
ADP and Pi is synthesised by ATP synthase to form ATP

1. Photophosphorylation- in chlorophyll during photosynthesis

2. Oxidative phosphorylation- in plant and animal cells during respiration

3. Substrate level phosphorylation- in plant and animal cells when phosphate groups are transferred to ADP from donor molecules

• energy is released in smaller, more manageable quantities

• hydrolysis of ATP is a single reaction that releases immediate energy whereas the breakdown of glucose is a long series of reactions so energy release takes longer

• metabolic processes: provides the energy needed to build up macromolecules from smaller ones

• movement: provides energy for sliding filament mechanism allowing the muscle to contract

• active transport: provides energy to change shape of carrier proteins allowing for molecules and ions to be moved against a concentration gradient

• secretion: needed to form lysosomes necessary for the secretion of cell products

• activation of molecules: Pi released can be used to phosphorylate other compounds in order to make them more reactive so lowering the activation energy in enzyme catalysed reactions