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“Endergonic Reactions”: Energy in the World of Biochemistry



Endergonic Reactions

In the broad field of biochemistry, the fundamental mechanisms that control life are essentially orchestrated by complicated chemical reactions. These reactions are divided into two categories: exergonic reactions and endergonic reactions. In this essay, we will dig into the intriguing world of endergonic reactions, providing light on their relevance, mechanics, and real-world applications.

Endergonic reactions are necessary for life because they provide the energy required for many biological processes such as muscular contractions, active transport, and the production of complex molecules such as DNA and proteins. Understanding the basic principles of endergonic processes is critical in industries ranging from medicine to agriculture, providing insights into metabolic pathways and energy transformation in living creatures.

Free energy | Endergonic vs exergonic reactions (article) | Khan Academy

We will begin by defining and distinguishing endergonic reactions from exergonic reactions, then continue on to investigate their significance in biology, look at the essential elements that drive these reactions, and lastly address practical applications and examples. Let us begin our exploration of the universe of endergonic reactions.

Endergonic versus Exergonic Reactions

To comprehend endergonic reactions, distinguish them from exergonic reactions.

Reactions that are Exergonic

Energy is released during exergonic reactions. They are distinguished by a decrease in free energy (G), which indicates that the reactants have greater free energy than the products. Exergonic reactions are spontaneous and do not require any additional energy input. Exergonic reactions are common in everyday life and include burning, the breakdown of food molecules during cellular respiration, and numerous chemical reactions.

Endothermic Reactions

Endergonic reactions, on the other hand, are not spontaneous and require an energy input to continue. These reactions result in a positive change in free energy (G), which means that the products have more free energy than the reactants. Endergonic reactions are required for activities that construct complex molecules and keep biological structures in place. They are not self-sustaining and must be powered by an external source of energy.

Endergonic Reactions’ Role in Biology

Endergonic reactions are critical in the biological world, triggering a range of important processes. These reactions are essential to the operation of living organisms and are classified into various categories:

Macromolecule Synthesis

Endergonic processes produce complex biological macromolecules such as proteins, nucleic acids (DNA and RNA), and polysaccharides. These macromolecules are the building blocks of life, and their creation necessitates the expenditure of energy. Protein synthesis, for example, a fundamental activity in all living cells, is predominantly driven by endergonic processes.

Active Transportation

To function effectively, cells must maintain particular concentrations of ions and chemicals both inside and outside their membranes. Active transport mechanisms rely on endergonic processes to move substances against concentration gradients, such as the sodium-potassium pump in mammalian cells. This energetic mechanism is required for nerve impulses, muscle contractions, and cell integrity.

Muscle Relaxation

Muscle cells contract using endergonic processes. The energy for muscular contraction comes from the endergonic breakdown of adenosine triphosphate (ATP). The energy created when ATP is broken down into adenosine diphosphate (ADP) and inorganic phosphate (Pi) powers the sliding of muscular filaments, resulting in muscle contraction.

PPT - Endergonic and Exergonic Reactions PowerPoint Presentation, free download - ID:597212


Respiratory Cellular Respiration

Endergonic processes are also important in cellular respiration. A sequence of chemical events breaks down glucose and other organic molecules to produce ATP in this metabolic pathway. The oxidation of glucose is an endergonic process that supplies energy for the survival and function of all aerobic organisms.

Factors Influencing Endergonic Reactions

Endergonic reactions are influenced by a number of circumstances, including the following:

Activation Power

The activation energy (Ea) is an energy barrier that must be surmounted in all chemical reactions, whether endergonic or exergonic. In the case of endergonic processes, activation energy is the amount of energy required to start the reaction.


Enzymes are biological catalysts that aid chemical reactions by decreasing the activation energy necessary for the reaction to take place. Enzymes serve a critical role in making endergonic processes thermodynamically viable. Enzymes stabilize transition states and stimulate the creation of reaction intermediates, lowering the amount of energy required for the reaction to occur.

Exergonic Reactions Coupling

Coupled with exergonic reactions, endergonic reactions can be made possible. This coupling involves connecting an energy-releasing (exergonic) response to an energy-absorbing (endergonic). The exergonic reaction’s energy output provides the necessary energy input for the endergonic reaction. This technique is frequently used by cellular processes to induce otherwise non-spontaneous reactions.

Exothermic Reaction Examples Found in Real Life | YourDictionary

 Examples and Practical Applications

Hydrolysis of ATP

The hydrolysis of adenosine triphosphate (ATP) is a well-known example of an endergonic process. In biological systems, ATP is the primary energy currency. When ATP is digested into adenosine diphosphate (ADP) and inorganic phosphate (Pi), energy is released that powers a variety of cellular operations. Energy from ATP hydrolysis, for example, is used for muscular contraction, active transport, and biosynthetic activities.

Replication of DNA

DNA replication, or the process of copying an organism’s genetic material, is a necessary endergonic response. DNA polymerases, the enzymes that catalyze the creation of new DNA strands, require energy to function. Similar to ATP hydrolysis, this energy is produced by the hydrolysis of deoxynucleoside triphosphates (dNTPs).


Several endergonic processes are involved in photosynthesis, the process by which plants and other photosynthetic organisms transform light energy into chemical energy. Carbon dioxide and water are transformed into glucose and oxygen in a sequence of endergonic reactions powered by sunlight energy during the photosynthetic process.

Synthesis of Proteins

Another important example of endergonic processes in operation is protein synthesis. It is divided into two stages: transcription and translation. DNA is transcribed into messenger RNA (mRNA) during transcription, which is an endergonic process that requires energy. mRNA is then utilized as a template to generate a protein through the assembly of amino acids, which is another energy-intensive process.

Neuronal Active Transport

Endergonic responses are required in neurons for the creation of nerve impulses and the transmission of electrical signals. The sodium-potassium pump actively transfers sodium and potassium ions against concentration gradients to keep the membrane potential at rest. This mechanism is essential for the normal functioning of the neurological system and necessitates a continuous supply of energy.

Exothermic reactions with Important Examples


Endergonic reactions are the driving force behind many biological activities, providing the energy required for complex chemical synthesis, active transport, muscular contractions, and more. While endergonic reactions are occurring,



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