ATP (3.1.6)
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ATP (Adenosine triphosphate) is a phosphorylated nucleotide derivative that acts as the immediate energy source in cells. It consists of three key components:
- Adenine: a nitrogenous base.
- Ribose: a five-carbon (pentose) sugar.
- Three phosphate groups: linked with high-energy bonds, which release energy when hydrolysed.
ATP provides an immediate energy source for biological processes. ATP is continuously hydrolysed (by ATP hydrolase) to form ADP + Pi and resynthesised within cells to support metabolic activities such as active transport, muscle contraction and protein synthesis.
The phosphate released from the hydrolysis of ATP can be used to phosphorylate other compounds.
ATP can be (re)synthesised by the condensation of ADP via a phosphorylation reaction requiring energy.
Phosphorylation of ADP is catalysed by the enzyme ATP synthase and occurs in mitochondria, during aerobic respiration (electron transport chain) and in chloroplasts, during photosynthesis (light-dependent reactions).
