Adenosine Triphosphate (ATP): Definition, Structure, and Function

Definition of Adenosine Triphosphate

Adenosine triphosphate, or ATP, is a chemical that transports energy throughout cells. It is the cell’s primary energy currency, and it is produced as a by-product of photophosphorylation (adding a phosphate group to a molecule using light energy), cellular respiration, and fermentation. ATP is used by all living things. It is used in signal transduction pathways for cell communication and is integrated into deoxyribonucleic acid (DNA) during DNA synthesis, in addition to being used as an energy source.

Structure of ATP

ATP is composed of three phosphate groups plus the molecule adenosine (which is composed of adenine and a ribose sugar). It is water soluble and has a high energy content due to the two phosphoanhydride bonds that connect the three phosphate groups.

Synthesis of ATP

ATP can be generated in a variety of ways. Photophosphorylation is a process that is exclusive to plants and cyanobacteria. It is the process by which ATP is synthesised from ADP utilising sunlight energy. It occurs during photosynthesis. ATP is also produced via the process of cellular respiration in a cell’s mitochondria. This can be accomplished through either aerobic respiration, which requires oxygen, or anaerobic respiration, which does not.

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From glucose molecule in the presence of oxygen, popularly known as aerobic respiration, generates ATP (along with carbon dioxide and water). Anaerobic respiration is a process that uses substances other than oxygen and is predominantly employed by archaea and bacteria that dwell in anaerobic conditions.

Fermentation is a non-oxygen-requiring method of creating ATP; it differs from anaerobic respiration in that it does not involve an electron transport chain. Yeast and bacteria are two species that employ fermentation to produce ATP.

Function of ATP

1. ATP as an Energy Source

ATP is the primary energy source for almost all cellular activity. Energy is released when the phosphate bond of ATP is broken down and transformed to adenosine diphosphate (ADP). Under typical conditions, the removal of one phosphate group yields 7.3 kilocalories per mole, or 30.6 kilojoules per mole. This energy drives all of the reactions that occur within the cell. ADP can again be turned back into ATP, adding up energy for further cellular activities.

2. Signal Transduction

ATP is a signaling molecule that is involved in cell communication. Kinases, which are enzymes that phosphorylate molecules, obtain phosphate groups from ATP. Kinases play a key role in signal transduction, which is the process by which a physical or chemical signal is passed from receptors present on the cell’s surface to intracellular receptors. Signals can be sent to cells to cause them to grow, metabolize, differentiate into certain types, or even die.

3. Synthesis of DNA

The nucleobase adenine is a component of adenosine, a molecule generated from ATP and immediately incorporated into RNA. CTP, GTP, and UTP are also used to make the other nucleobases in RNA. Adenine is likewise contained in DNA, and its integration is quite similar, with the exception that ATP is transformed into the form deoxyadenosine triphosphate (dATP) before becoming a component of a DNA strand.


Other compounds with similar names to ATP include adenosine diphosphate (ADP), adenosine monophosphate (AMP), and cyclic AMP (cAMP). It is critical to understand the differences between these compounds in order to avoid confusion.

What is ADP?

This article has already covered adenosine diphosphate (ADP), which is also known as adenosine pyrophosphate (APP) in chemistry. It varies from ATP in that it contains two phosphate groups. With the removal of a phosphate group, ATP becomes ADP, and this reaction releases energy. ADP is synthesized from AMP. During cellular respiration, cells obtain the energy they require by cycling between ADP and ATP.

What is AMP?

Adenosine monophosphate (AMP), commonly known as 5′-adenylic acid, has a single phosphate group. This molecule can be found in RNA and contains adenine, which is a component of the genetic code. It can be generated alongside ATP by combining ADP molecules or by hydrolyzing ATP. It is also produced when RNA is degraded. It can be turned into uric acid, a component of urine, and then expelled through the bladder.

What is cAMP?

Cyclic adenosine monophosphate (cAMP) is a cellular messenger produced from ATP. It is employed for signal transduction and activation of specific protein kinases. It can be decomposed into AMP. Certain malignancies, such as carcinoma, may be affected by cAMP pathways.

It is also involved in metabolism in bacteria. When a bacterial cell does not produce enough energy (for example, due to a lack of glucose), high cAMP levels rise, which activates genes that utilize energy sources other than glucose.

Biology Related Terms

Cellular respiration: Cellular respiration is the process through which energy from nutrients is transformed into ATP.

Signal transduction: The transmission of signals from the outside to the inside of a cell.

Hydrolysis: Hydrolysis is the process of breaking a molecule’s link and splitting it into smaller molecules with the release of water. Kinase – An enzyme that transfers a phosphate group from one molecule to another.

Related Questions 

1. How can ATP be produced?

  • A. Fermentation
  • B. Cellular respiration
  • C. Photophosphorylation
  • D. All of the above

2. Where is ATP produced in the cell?

  • A. Mitochondria
  • B. Nucleus
  • C. Ribosomes
  • D. Endoplasmic reticulum

3. What form of genetic material contains adenine?

  • A. DNA
  • B. RNA
  • C. Both DNA and RNA
  • D. Neither DNA nor RNA


ATP AND BIOLOGICAL ENERGY. https://www2.estrellamountain.edu/

Adenosine triphosphate: https://www.britannica.com/science/adenosine-triphosphate

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