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Diff: Adenosine Triphosphate (ATP)

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'''Adenosine Triphosphate (ATP)''' is a crucial molecule that serves as the primary energy carrier in cells. It plays a central role in various biological processes, providing the energy necessary for cellular activities. ATP is often referred to as the "energy currency" of the cell due to its fundamental role in energy transfer within living organisms.
==Structure and Composition==
ATP is a nucleotide composed of three main components:
	'''Adenosine triphosphate''' ('''ATP''') is a nucleotide used by cells to transfer energy between reactions. It is often called the cell's energy currency because cells continually make it, break it down, and use the released free energy to drive work.

Adenine: A nitrogenous base.
	ATP is found in all known living cells. It is not a long-term energy store like fat or glycogen. It is a short-term carrier that links energy-releasing reactions to energy-requiring reactions.

Ribose: A five-carbon sugar.
	== Structure ==
	ATP is made from:

Three Phosphate Groups: Linked together in a chain.
	* Adenine, a nitrogen-containing base.
	* Ribose, a five-carbon sugar.
	* Three phosphate groups.

The chemical structure of ATP is characterised by its high-energy phosphate bonds, particularly those between the second and third phosphate groups.
==Energy Storage and Release==
The energy stored in ATP is released during a hydrolysis reaction, in which water is used to break the high-energy phosphate bond. This reaction results in the formation of adenosine diphosphate (ADP) and inorganic phosphate (Pi), releasing energy that can be utilised by cells.
	The related molecules ADP and AMP have two and one phosphate groups respectively.

ATP+H2O→ADP+Pi+Energy
	== ATP Hydrolysis ==
	Cells commonly use ATP by hydrolysing it to ADP and inorganic phosphate:

Conversely, energy from cellular processes can be used to regenerate ATP from ADP and Pi in a process known as phosphorylation.
==Cellular Functions==
	ATP + H2O -> ADP + Pi + free energy

==== Energy Transfer ====
ATP facilitates energy transfer within cells by providing the necessary energy for various cellular activities, including:
	The useful energy does not come from simply "breaking a bond" in isolation. It comes from the overall reaction, including formation of more stable products and changes in water, phosphate, and protein interactions. This distinction matters because simple textbook wording can make ATP sound like a tiny battery with energy stored only in one bond.

Muscle Contraction: ATP is essential for muscle contraction and relaxation.
	== Cellular Work ==
	ATP supports many types of cellular work, including:

Active Transport: ATP powers the movement of ions and molecules across cell membranes.
	* Muscle contraction and relaxation.
	* Active transport across membranes.
	* Protein phosphorylation in signalling pathways.
	* Biosynthesis of macromolecules.
	* Vesicle transport and other motor-protein activity.
	* Maintenance of ion gradients in nerve and muscle cells.

Synthesis of Biomolecules: ATP provides energy for the synthesis of proteins, nucleic acids, and other cellular components.
	Kinases use ATP to transfer phosphate groups to proteins or other molecules. ATPases use ATP hydrolysis to drive mechanical or transport processes.

==== Signal Transduction ====
ATP is involved in intracellular signalling pathways and serves as a signalling molecule in extracellular processes. For example, extracellular ATP can function as an extracellular signalling molecule, influencing processes like neurotransmission.
	== Production ==
	Cells regenerate ATP from ADP and phosphate. Main routes include glycolysis, substrate-level phosphorylation, oxidative phosphorylation in mitochondria, and photosynthetic phosphorylation in plants and some microbes.

==== Metabolism ====
ATP is a key player in cellular metabolism, participating in both catabolic and anabolic reactions. It acts as an intermediary that couples energy-releasing reactions with energy-consuming reactions.
==Cellular Respiration==
ATP is generated through cellular respiration, a process that occurs in the mitochondria. During the breakdown of glucose through glycolysis and the citric acid cycle, electrons are transferred to the electron transport chain, leading to the production of ATP through oxidative phosphorylation.
==ATP in Health and Medicine==
ATP has applications in various fields, including medicine and research. It is used as a marker of cell viability and is involved in diagnostic techniques. Additionally, ATP is utilised in pharmaceutical research and drug development.
==Conclusion==
Adenosine Triphosphate (ATP) is a vital molecule that plays a central role in cellular energy transfer and various biological processes. Its unique structure and the ability to release and store energy make it indispensable for the functioning of living organisms.
	In aerobic eukaryotic cells, mitochondria make much of the ATP by using energy from food molecules and oxygen to maintain a proton gradient that drives ATP synthase.

	== Signalling Roles ==
	ATP also has signalling roles. Inside cells it is used by enzymes such as kinases. Outside cells, ATP can act through purinergic receptors and contribute to communication between cells, including in nerves, immune responses, and tissue injury.

	== See Also ==
	* [[Choline]]
	* [[Hydroxyapatite]]
	* [[Macronutrient]]

	== References ==
	* [https://pubmed.ncbi.nlm.nih.gov/31985968/ PubMed: Physiology, Adenosine Triphosphate]
	* [https://pubchem.ncbi.nlm.nih.gov/compound/adenosine%20triphosphate PubChem: Adenosine triphosphate]
	* [https://openstax.org/books/biology/pages/6-4-atp-adenosine-triphosphate OpenStax Biology: ATP, adenosine triphosphate]
	* [https://www.ncbi.nlm.nih.gov/books/NBK26882/ NCBI Bookshelf: How cells obtain energy from food]
	* [https://pubmed.ncbi.nlm.nih.gov/35353443/ PubMed: Complex roles of ATP in bioenergetics]
	* [https://www.acs.org/molecule-of-the-week/archive/a/adenosine-triphosphate.html American Chemical Society: Adenosine triphosphate]

	[[Category:Biochemistry]]
	[[Category:Biology]]