Nucleic Acids: - ATP

- ATP - 

ATP - Adenosine triphosphate is a nucleotide and has three phosphate groups and is key in storing energy. The bonds between the phosphate groups are unstable therefore have a low activation energy - can be easily broken. They release a considerable amount of energy. In living cells it is only the terminal phosphate that is removed

Structure of ATP:

• Adenine - nitrogen containing organic base.
• Ribose - sugar molecule with 5 carbon ring structure - backbone
• Phosphates - chain of three phosphate groups

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Synthesis of ATP: ATP to ADP is a reversible reaction therefore energy can be used to add an inorganic phosphate to ADP to re-form ATP. This reaction is catalysed by enzyme ATP synthase. The reaction is a condensation reaction.

The synthesis ATP from ADP involves addition of phosphate molecule to ADP.

• In chlorophyll containing plant cells during photosynthesis (photophosphorylation)
• In plant and animal cells during respiration (oxidative phosphorylation)
• In plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation)

Roles of ATP:

• ATP serves as an immediate energy source of a cell
• Cells do not require large quantities of ATP
• ATP is rapidly re-formed from ADP and inorganic phosphate

ATP is required as energy-requiring processes in cells:

• Metabolic processes
• Movement
• Active transport
• Secretion
• Activation of molecules