The living cells need a continuous supply of free energy for various metabolic work. ATP is the special carrier of free energy. It plays a central role in transfer of free energy.
ATP was discovered by German scientist Karl Lohmann in 1929. F.A.Lipmann postulated that ATP is the universal carrier of chemical energy in the cells.
Structure of ATP Molecule:
Adenosine Triphosphate (ATP) is regarded as energy currency of the cell and it consists of-
Adenine, a nitrogenous base (C5H4N5).
Ribose, a pentose sugar (C5H10O5).
Three phosphate molecules.
Functions of ATP (Adenosine Triphosphate):
Adenosine Triphosphate functions as a universal energy carrier of living systems.
Wherever energy of more than 37.25 kJ or 8.9 kcal value is available, ATP synthesis can occur. ATP thus stores small packets of energy in its molecules.
ATP synthesis is the only mode of trapping energy released during oxidative metabolism. This avoids wastage.
It is mobile in the cell. It, therefore, reaches all parts of the cell away from the region of ATP synthesis.
It activates a number of chemicals by functioning as a phosphorylating agent. Example- conversion of glucose to fructose 1,6-diphosphate.
It provides small amounts of energy required for establishing new chemical bonds during biosynthesis.
ATP provides energy for muscle contraction.
It is involved in the transport of substances against their concentration gradient. The phenomenon is called active transport.
ATP energizes every activity of the cell like osmosis, endocytosis, exocytosis, cyclosis, etc.
ATP molecules can collect at one place and provide a large amount of energy for performing heavy work.
Explain why ATP is the most suitable form of energy for powering the cellular processes:
Adenosine Triphosphate (ATP) is the energy currency of the cell. It is the most efficient high energy compound and is the most suitable form of energy for providing the various cellular metabolic processes for the following reasons-
ATP is very easily hydrolyzed to form ADP (Adenosine diphosphate) and energy which is used for various biochemical processes. So, we can say that ATP releases its stored energy very soon.
ATP can be easily synthesized from ADP when it is supplied free energy which is set free by the oxidation of food-stuffs during respiration.
C6H12O6 + 6O2 ———-> 6CO2 +6H2O + ATP
ATP can be easily stored in the cells. Mitochondria contain ATP and are the so-called Powerhouses of the cell.
ATP can be easily transferred from one part of the body to another. So, ATP is easily formed, it can be easily stored, transformed, and transported. Keeping these qualities of ATP in mind. ATP is considered the best type of energy-rich compound for cellular processes.