Adenosine triphosphate

Interactive animation of the structure of ATP
The cycles of synthesis and degradation of ATP; 2 and 1 represent input and output of energy, respectively.
This image shows a 360-degree rotation of a single, gas-phase magnesium-ATP chelate with a charge of −2. The anion was optimized at the UB3LYP/6-311++G(d,p) theoretical level and the atomic connectivity modified by the human optimizer to reflect the probable electronic structure.
An example of the Rossmann fold, a structural domain of a decarboxylase enzyme from the bacterium Staphylococcus epidermidis with a bound flavin mononucleotide cofactor.

Organic compound and hydrotrope that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis.

- Adenosine triphosphate

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Adenosine monophosphate


This nucleotide contains the five-carbon sugar deoxyribose (at center), a nucleobase called adenine (upper right), and one phosphate group (left). The deoxyribose sugar joined only to the nitrogenous base forms a <u title="Nucleotide">Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a <u title="Deoxyadenosine monophosphate" href="deoxyadenosine monophosphate">nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate.

AMP plays an important role in many cellular metabolic processes, being interconverted to ADP and/or ATP.


Nucleobase (a purine derivative).

Adenine structure, with standard numbering of positions in red.
Adenine on Crick and Watson's DNA molecular model, 1953. The picture is shown upside down compared to most modern drawings of adenine, such as those used in this article.

Its derivatives have a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate (ATP) and the cofactors nicotinamide adenine dinucleotide (NAD), flavin adenine dinucleotide (FAD) and Coenzyme A.

Cofactor (biochemistry)

Non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst .

The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.
A simple [Fe2S2] cluster containing two iron atoms and two sulfur atoms, coordinated by four protein cysteine residues.
The redox reactions of nicotinamide adenine dinucleotide.

Many contain the nucleotide adenosine monophosphate (AMP) as part of their structures, such as ATP, coenzyme A, FAD, and NAD+.


Metabolic pathway that converts glucose , into pyruvic acid (CH3COCO2H).

Summary of aerobic respiration
Summary of the 10 reactions of the glycolysis pathway
Glycolysis pathway overview.
Eduard Buchner. Discovered cell-free fermentation.
Otto Meyerhof. One of the main scientists involved in completing the puzzle of glycolysis
Yeast hexokinase B
Bacillus stearothermophilus phosphofructokinase
Yeast pyruvate kinase

The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH).

Muscle contraction

Activation of tension-generating sites within muscle cells.

Types of muscle contractions
In vertebrate animals, there are three types of muscle tissues: 1) skeletal, 2) smooth, and 3) cardiac
Organization of skeletal muscle
Structure of neuromuscular junction.
Sliding filament theory: A sarcomere in relaxed (above) and contracted (below) positions
Cross-bridge cycle
Muscle length versus isometric force
Force–velocity relationship: right of the vertical axis concentric contractions (the muscle is shortening), left of the axis eccentric contractions (the muscle is lengthened under load); power developed by the muscle in red. Since power is equal to force times velocity, the muscle generates no power at either isometric force (due to zero velocity) or maximal velocity (due to zero force). The optimal shortening velocity for power generation is approximately one-third of maximum shortening velocity.
Swellings called varicosities belonging to an autonomic neuron innervate the smooth muscle cells.
Cardiac muscle
Key proteins involved in cardiac calcium cycling and excitation-contraction coupling
A simplified image showing earthworm movement via peristalsis
Asynchronous muscles power flight in most insect species. a: Wings b: Wing joint c: Dorsoventral muscles power the upstroke d: Dorsolongitudinal muscles (DLM) power the downstroke. The DLMs are oriented out of the page.
Electrodes touch a frog, and the legs twitch into the upward position

Though the muscle is doing a negative amount of mechanical work, (work is being done on the muscle), chemical energy (of fat or glucose, or temporarily stored in ATP) is nevertheless consumed, although less than would be consumed during a concentric contraction of the same force.

Oxidative phosphorylation

The electron transport chain in the cell is the site of oxidative phosphorylation. The NADH and succinate generated in the citric acid cycle are oxidized, releasing the energy of O2 to power the ATP synthase.
Reduction of coenzyme Q from its ubiquinone form (Q) to the reduced ubiquinol form (QH2).
Complex I or NADH-Q oxidoreductase. The abbreviations are discussed in the text. In all diagrams of respiratory complexes in this article, the matrix is at the bottom, with the intermembrane space above.
Complex II: Succinate-Q oxidoreductase.
The two electron transfer steps in complex III: Q-cytochrome c oxidoreductase. After each step, Q (in the upper part of the figure) leaves the enzyme.
Complex IV: cytochrome c oxidase.
Mechanism of ATP synthase. ATP is shown in red, ADP and phosphate in pink and the rotating γ subunit in black.

Oxidative phosphorylation (UK, US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate (ATP).

Cellular respiration

Typical eukaryotic cell
Out of the cytoplasm it goes into the Krebs cycle with the acetyl CoA. It then mixes with CO2 and makes 2 ATP, NADH, and FADH. From there the NADH and FADH go into the NADH reductase, which produces the enzyme. The NADH pulls the enzyme's electrons to send through the electron transport chain. The electron transport chain pulls H+ ions through the chain. From the electron transport chain, the released hydrogen ions make ADP for an result of 32 ATP. O2 provides most of the energy for the process and combines with protons and the electrons to make water. Lastly, ATP leaves through the ATP channel and out of the mitochondria.
Stoichiometry of aerobic respiration and most known fermentation types in eucaryotic cell. Numbers in circles indicate counts of carbon atoms in molecules, C6 is glucose C6H12O6, C1 carbon dioxide CO2. Mitochondrial outer membrane is omitted.

Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.


Double-membrane-bound organelle found in most eukaryotic organisms.

Two mitochondria from mammalian lung tissue displaying their matrix and membranes as shown by electron microscopy
Simplified structure of a mitochondrion.
Cross-sectional image of cristae in a rat liver mitochondrion to demonstrate the likely 3D structure and relationship to the inner membrane
Electron transport chain in the mitochondrial intermembrane space
Transmission electron micrograph of a chondrocyte, stained for calcium, showing its nucleus (N) and mitochondria (M).
Typical mitochondrial network (green) in two human cells (HeLa cells)
Model of the yeast multimeric tethering complex, ERMES
Evolution of MROs
The circular 16,569 bp human mitochondrial genome encoding 37 genes, i.e., 28 on the H-strand and 9 on the L-strand.

Mitochondria use aerobic respiration to generate most of the cell's supply of adenosine triphosphate (ATP), which is subsequently used throughout the cell as a source of chemical energy.

ATP synthase

Molecular model of ATP synthase determined by X-ray crystallography. Stator is not shown here.
Bovine mitochondrial ATP synthase. The FO, F1, axle, and stator regions are color coded magenta, green, orange, and cyan respectively.
Simplified model of FOF1-ATPase alias ATP synthase of E. coli. Subunits of the enzyme are labeled accordingly.
Rotation engine of ATP synthase.
FO subunit F6 from the peripheral stalk region of ATP synthase.
Mechanism of ATP synthase. ADP and Pi (pink) shown being combined into ATP (red), while the rotating γ (gamma) subunit in black causes conformational change.
Depiction of ATP synthase using the chemiosmotic proton gradient to power ATP synthesis through oxidative phosphorylation.

ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi).


Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms.

Structure of triphosphoric acid
Polyphosphoric acid
Cyclic trimetaphosphate
Adenosine diphosphate (ADP)

In biology, the polyphosphate esters ADP and ATP are involved in energy storage.