Metabolic energy


Metabolic energy: it is generated by living organisms through chemical oxidation processes as a product of the food they consume.

Basic concept:

It is the set of chemical reactions that cells carry out to obtain energy and synthesize compounds.

Types of metabolic energy reaction


In which the nutrient cell that incorporates the external environment, builds its own molecules and these consume energy, which are endergonic reactions.


Where the cell breaks down substances (glucose) and obtains energy (exergonic reactions), which it uses to fulfill its cellular functions, such as:

Synthesis of organic compounds:

Molecules rich in chemical energy made up of smaller molecules.

Substance transport:

Cells must transport substances across membranes and into the cell; many cells are mobile by specialized organelles (eyelashes and flagella), by internal cytoskeletal contractions (microtubules) (muscle and others) or.

Reproduce and continue life:

Since life is a competition for a better use of energy resources, a cell can be considered as a complex energy transformation system, where the associated catabolic and anabolic reactions, the energy released in one reaction is used by another; where cells synthesize energy transport molecules (ATP), which are capable of capturing energy from exergonic and endergonic reactions carried out, and where cells regulate chemical reactions using biocatalysts: enzymes.

Types of metabolic energy reactions

Metabolism comprises several types of reactions that can be grouped into two main categories: the degradation reactions of organic molecules and the synthesis reactions of other biomolecules.

Metabolic degradation reactions:

They constitute cellular catabolism (or catabolic reactions). They involve the oxidation of energy-rich molecules such as glucose and other sugars (carbohydrates). Because these reactions release energy, they are called exergonic.

Synthesis reactions:

They constitute cellular anabolism (or anabolic reactions). These carry out processes of reduction of molecules to form others rich in stored energy, such as glycogen. As these reactions consume energy, they are called endergonal.

Sources of metabolic energy

  1. The main sources of metabolic energy are glucose molecules and fatty acids. It is a group of biomolecules that can be rapidly oxidized to energy.
  2. Glucose molecules come mainly from carbohydrates ingested in the diet, such as rice, bread, noodles, and other starchy vegetable derivatives. When glucose is low in the blood, it can also be obtained from glycogen molecules stored in the liver.
  3. In prolonged fasts, or in processes that require an additional expenditure of energy, it is necessary to obtain this energy from the fatty acids that are mobilized from the fatty tissue.
  4. These fatty acids undergo a series of metabolic reactions that activate them and allow their transport to the interior of the mitochondria, where they are oxidized. This process is called β-fatty acid oxidation and provides up to 80% additional energy under these conditions.
  5. Proteins and fats are the last reserve to synthesize new glucose molecules, especially in cases of extreme fasting. This reaction is of the anabolic type and is known as gluconeogenesis.

Examples of metabolic energy


It is the metabolic process through which energy is obtained from glucose.


Metabolic process carried out by plants. Chloroplasts transform organic matter into inorganic matter through the energy of sunlight.

Carbohydrate synthesis:

The human body, through saliva, gastric acids, and certain enzymes, obtains glucose from carbohydrate molecules.

More examples:

Starch synthesis, protein synthesis, lipid metabolism, fat metabolism, fructose metabolism, urea metabolism, insulin metabolism.

What is ATP?

ATP, adenosine triphosphate, nucleotides composed of adenine (nucleus-base), a mite (ribose) and three phosphate groups, is a substance that exists in all living beings and is very important because it works as a direct source of energy for many processes, is the ENERGY MODE. This energy is found in the high-energy chemical bonds of phosphates. Cells use ATP to capture, transfer, and store the free energy needed to do chemical work.

Structure of ATP

When ATP breaks down because it reacts with water (H2O), “hydrolyzed” to occur, ADP (adenosine diphosphate) and a phosphate molecule to release the energy contained in the bond in this process, this reaction is catalyzed by an enzyme called ATPase, that is, enzymes that break down ATP; many of them have this property, using their breakdown energy (hydrolysis) to transport ions from one side of the membranes to the other.

  1. Hydrolysis of ATP gives: ATP + H2O -> ADP + Pi
  2. Hydrolysis of adenosine diphosphate gives: ADP + H2O -> AMP + Pi
  3. The hydrolysis of ATP into ADP (adenosine diphosphate) or AMP (adenosine monophosphate) releases large amounts of energy, which is exploited by absorbing reactions to be carried out.

The transformation of ATP into ADP and AMP is a highly dynamic mechanism that satisfies the energy needs of the cell. In fact, the hydrolysis of ATP is reversible, and the three forms of adenine phosphate are interconvertible with each other.

Metabolism overview

Cells are continually performing thousands of chemical reactions necessary to keep cells and the entire body alive and healthy. These chemical reactions are often linked in chains or pathways. All the chemical reactions that take place within a cell are known together as the cell’s metabolism.

To give us an idea of ​​the complexity of metabolism, let’s examine the metabolic diagram below. In fact, the main metabolic pathways of a eukaryotic cell, like the cells that make up the human body. Each line is a reaction and each circle is a reactant or product. The metabolism is complex and highly interconnected, with many different pathways feeding each other.

Fundamental eukaryotic metabolic networks indicate that metabolism is complex and highly interconnected, with many different pathways feeding on each other.

In the metabolic network of the cell, some chemical reactions release energy and can occur spontaneously (without energy input). However, others need energy added to be able to be realized. Just as you need to feed continuously to replenish what your body uses, cells also need a continuous supply of energy to increase their energy-requiring chemical reactions.

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