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Difference Between ADP and ATP

Main Difference

The main difference between ADP and ATP is that ADP molecule consists of two molecules of the phosphate group from ATP, and the third molecule is a breakdown which results in the release of the high amount of energy, whereas ATP consists of three molecules of phosphate and the third phosphate is bonded to other phosphate groups having a high energy bond.

ADP vs. ATP

The abbreviation of ADP is Adenosine Di Phosphate, while the abbreviation of ATP is Adenosine Triphosphate. The molecular structure of ADP contains adenosine (an adenine ring and a ribose sugar) and two phosphate groups (diphosphate), whereas the molecular structure of ATP contains adenosine (an adenine ring and a ribose sugar) and three phosphate groups (triphosphate). ADP consists of two phosphate groups; on the other hand, ATP consists of three phosphate groups.

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The chemical formula of ADP is C10H15N5O10­P2; on the contrary, the chemical formula of ATP is written as C10H16N5O13P3. The molar mass of ADP consists of 427.201 g/mole; conversely, the molar mass of ATP consists of 507.18 g/mol. The density of ADP is calculated as 2.49 g/mL; on the flip side, the density of ATP is calculated as 1.04 g/cm3.

ADP is generally a low energy molecule as matched to ATP; on the flip side, ATP is usually a high-energy molecule as related to ADP. The energy releasing mechanism for ADP is ADP + H2O → AMP + PPi; on the contrary, the energy-releasing mechanism for ATP is ATP + H2O → ADP + Pi ΔG˚ = −30.5 kJ/mol (−7.3 kcal/mol).

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Functions of ADP are described as it is used in blood platelet activation, or it plays a role in mitochondrial ATP synthase complex, used in catabolic pathways such as glycolysis, citric acid cycle, and oxidative phosphorylation. On the flip side, functions of ATP are described as it plays a role in the synthesis of macromolecules such as DNA, RNA, metabolism in cells, amino acid activation, and protein, active transport of molecules, maintaining cell structure, and contribute to cell signaling. The less amount of energy is stored in the ADP molecule as it contains only two molecules of phosphate, while a large amount of energy is stored in ATP as it consists of three molecules of phosphate.

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The third molecule of phosphate is added to the ADP by using some energy from food during the conversion of ADP to ATP, whereas the third molecule of phosphate is hydrolyzed by water or releasing energy during the conversion of ATP to ADP. The ADP molecule is generally formed from ATP by the process of mitosis and conserving homeostasis; on the contrary, the ATP is formed from ADP by fermentation, photophosphorylation, and cellular respiration.

Comparison Chart

ADPATP
ADP generally states to the organic compound, which works as the final product of the energy transmission of the ATP.ATP usually mentions to an organic molecule which consists of adenosine and three phosphate molecules and assists as the energy bank of the cell.
Abbreviation
Adenosine Di PhosphateAdenosine Triphosphate
Molecular Structure
Comprises adenosine (an adenine ring and a ribose sugar) and two phosphate groups (diphosphate)Comprises adenosine (an adenine ring and a ribose sugar) and three phosphate groups (triphosphate)
Number of Phosphate Groups
Consists of two phosphate groupsConsists of three phosphate groups
Chemical Formula
C10H15N5O10­P2C10H16N5O13P3
Molar Mass
427.201 g/mole507.18 g/mol
Density
2.49 g/mL1.04 g/cm3
Energy State of Molecule
Generally, a low energy molecule as matched to ATPUsually a high-energy molecule as related to ADP
Energy Releasing Mechanism
ADP + H2O → AMP + PPiATP + H2O → ADP + Pi ΔG˚ = −30.5 kJ/mol (−7.3 kcal/mol)
Amount of Energy Stored
The less amount of energy is stored as it contains only two molecules of phosphateA large amount of energy is stored in ATP as it consists of three molecules of phosphate
Conversion
The third molecule of phosphate is added to the ADP by using some energy from food during the conversion of ADP to ATPThe third molecule of phosphate is hydrolyzed by water or releasing energy during the conversion of ATP to ADP
Processes
Generally formed from ATP by the process of mitosis and conserving homeostasisFormed from ADP by fermentation, photophosphorylation and cellular respiration
Functions
Used in blood platelet activation or it plays a role in mitochondrial ATP synthase complexPlays a role in metabolism in cells, amino acid activation, synthesis of macromolecules such as DNA, RNA, and protein

What is ADP?

Adenosine Diphosphate (ADP) generally states to the organic compound, which works as the final product of the energy transmission of the ATP. ADP is considered an important component of nucleic acids as it is one of the most significant and one of the most abundant molecules present in the cell.

The molecular structure of ADP from which it is formed contains adenosine (an adenine ring and a ribose sugar) and two phosphate groups (diphosphate). This structure of ADP is vital for energy flow in biological systems.

ADP is formed as a product of de-phosphorylation of a molecule of ATP through enzymes called ATPase. The IUPAC name given to ADP is [(2R,3S,4R,5R)-5-(6-aminopterin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl phosphonic hydrogen phosphate. The ADP molecules are also called as adenosine 5′-diphosphate.

Functions of ADP

  • It is used in blood platelet activation
  • It plays a role in mitochondrial ATP synthase complex
  • Used in catabolic pathways such as glycolysis, citric acid cycle, and oxidative phosphorylation
  • It usually stores and releases energy
  • It gives the energy required to receive and send ions that transmit signals between neurons.

What is ATP?

Adenosine Triphosphate (ATP) usually mentions to an organic molecule which consists of adenosine and three phosphate molecules and assists as the energy bank of the cell. ATP is specifically used by biological individuals as a coenzyme of intracellular chemical energy transmission within cells for a breakdown as it is the central energy transporter molecule used in living organisms.

ATP is formed from ADP by fermentation, photophosphorylation, and cellular respiration. The molecular structure of ATP from which it is composed usually contains adenosine (an adenine ring and a ribose sugar) and the three phosphate groups (triphosphate).

Biosynthesis of ATP By

  • Glycolysis: 2NAD+ + 2 Pi + 2 ADP + Glucose = 2 pyruvates + 2 ATP +2 H2O + 2 NADH
  • Fermentation: Glucose = 2CH3CH(OH)COOH + 2 ATP

Functions

  • It plays a role in the breakdown in cells
  • Amino acid activation
  • Synthesis of macromolecules such as DNA, RNA, and protein
  • Active transport of molecules
  • Maintaining cell structure
  • Contribute to cell signaling

Key Differences

  1. ADP consists of two phosphate groups; on the other hand, ATP consists of three phosphate groups.
  2. Adenosine Di Phosphate is the abbreviation of ADP, while Adenosine Triphosphate is the abbreviation of ATP.
  3. The ADP’s molecular structure consists of adenosine and two phosphate groups, whereas the ATP’s molecular structure consists of adenosine and three phosphate groups.
  4. C10H15N5O10­P2 is the chemical formula of ADP; on the contrary, C10H16N5O13P3 is the chemical formula of ATP.
  5. The molar mass of ADP contains 427.201 g/mole; conversely, the molar mass of ATP contains 507.18 g/mol.
  6. The density of ADP is considered as 2.49 g/mL; on the flip side, the density of ATP is considered as 1.04 g/cm3.
  7. ADP is generally deliberated as a low energy molecule; on the flip side, ATP is usually deliberated a high-energy molecule.
  8. The energy releasing mechanism for ADP is ADP + H2O → AMP + PPi; on the contrary, the energy-releasing mechanism for ATP is ATP + H2O → ADP + Pi ΔG˚ = −30.5 kJ/mol (−7.3 kcal/mol).
  9. Plays a role in mitochondrial ATP synthase complex, blood platelet activation, used in catabolic ways such as citric acid cycle, glycolysis, and oxidative phosphorylation are the functions of ADP in which it is used mainly; on the flip side, plays a role in metabolism in cells, amino acid activation, and synthesis of macromolecules such as DNA, RNA, and protein are the main functions of ATP.
  10. As the ADP molecule consists of only two molecules of phosphate, so that’s mean it has less amount of energy stored, while ATP consists of three molecules of phosphate, so a large amount of energy is stored in ATP molecule.
  11. During the conversion of ADP to ATP, the third molecule of phosphate is added to the ADP by using some energy from the food, whereas during the conversion of ATP to ADP, the third molecule of phosphate is hydrolyzed by water or by releasing some energy.
  12. By the process of mitosis and maintain homeostasis, the ADP molecule is then formed from ATP; on the contrary, the ATP is produced from ADP by fermentation, photophosphorylation, and cellular respiration.

Conclusion

Above discussion concludes that the ADP molecule consists of two molecules of a phosphate group, and the third molecule is a breakdown which results in the release of a high amount of energy, but it is generally a low energy molecule, whereas ATP consists of three molecules of phosphate and the third phosphate are bonded to other phosphate groups with having a high energy bond, and it is a high energy molecule.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White