Energy Currency of the Cell

All living things including plants, animals, birds, insects, humans need energy for the proper functioning of cells, tissues and other organ systems. As we are aware that green plants, obtain their energy from the sunlight, and animals get their energy by feeding on these plants. Energy acts as a source of fuel. We, humans, gain energy from the food we eat, but how are the energy produced and stored in our body.

Here, in this article, let us learn more in detail about the ATP- Adenosine triphosphate its structure, functions and its importance.

What is ATP- Adenosine Triphosphate?

ATP – Adenosine triphosphate is called the energy currency of the cell.

It is the organic compound composed of the phosphate groups, adenine, and the sugar ribose. These molecules provide energy for various biochemical processes in the body. Therefore, it is called “Energy Currency of the Cell”. These ATP molecules are synthesized by Mitochondria, therefore it is called powerhouse of the cell.

The ATP molecule was discovered in the year 1929 by German chemist Karl Lohmann. Later in the year 1948, Scottish biochemist Alexander Todd was the first person to synthesized the ATP molecule.

ATP – the energy-carrying molecules are found in the cells of all living things. These organic molecules function by capturing the chemical energy obtained from the digested food molecules and are later released for different cellular processes.

Explore more: Life Processes

Structure of ATP molecule

Structure of ATP molecule

ATP – Adenosine triphosphate is a nucleotide, which is mainly composed of the molecule adenosine and three phosphate groups. It is soluble in water and has a high energy content, which is primarily due to the presence of two phosphoanhydride bonds connected to the three phosphate groups.

The triphosphate tail of ATP is the actual power source which the cell taps. The available energy is contained in the bonds between the phosphates and is released when they are broken or split into molecules. This occurs through the addition of a water molecule (hydrolysis). Usually, only the outer phosphate group is removed from ATP to yield energy; when this occurs, ATP – Adenosine triphosphate is converted into ADP – adenosine diphosphate, it is the form of the nucleotide having only two phosphates.

ATP molecules are largely composed of three essential components.

  • The pentose sugar molecule i.e. ribose sugar.
  • Nitrogen base- Adenine, attached to the first carbon of this sugar molecule.
  • The three phosphate groups which are attached in a chain to the 5th carbon of the pentose sugar. The phosphoryl groups, starting with the group closest to the ribose sugar, are referred to as the alpha, beta, and gamma phosphates. These phosphates play an important role in the activity of ATP.

How is energy produced by the ATP molecules?

The three phosphate groups present in this ATP molecule are called high energy bonds as they are involved in the liberation of a huge amount of energy when they are broken. This molecule provides energy for various life processes without which life cannot exist.

It is used by various enzymes and structural proteins in cellular processes like biosynthetic reactions, cell divisions, etc. This “energy currency of the cell” is produced during cellular respiration where a digested simple molecule of food is utilized.

Once after the energy is produced by the ATP molecules, they are stored in its bonds which are later utilized by the cells by breaking the bonds whenever required

Also, refer Mitochondria

Functions of ATP

The ATP is used for various cellular functions, including transportation of different molecules across cell membranes. Other functions of ATP include supplying the energy required for the muscle contraction, for the blood circulation, and various body movements. A significant role of ATP apart from energy production includes:

Synthesizing the multi-thousands of types of macromolecules that the cell requires to exist. ATP molecule is also used as a switch to control chemical reactions and to send messages.

Importance of ATP Molecule in Metabolism

  1. These ATP molecules can be recycled after every reaction.
  2. ATP molecule provides energy for both the exergonic and endergonic processes.
  3. ATP serves as an extracellular signalling molecule and acts as a neurotransmitter in both central and  peripheral nervous systems.
  4. It is the only energy, which can be directly used for different metabolic process. Other forms of chemical energy need to be converted into ATP before they can be used.
  5. It plays an important role in the Metabolism – A life-sustaining chemical reactions including cellular division, fermentation, photosynthesis, photophosphorylation, aerobic respiration, protein synthesis, exocytosis, endocytosis and motility.

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