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Metabolism – Metabolic Pathways

Grade 7
Jun 7, 2023



The movement of food through a sequence of chemical processes is called metabolism. Metabolism is a set of chemical reactions that occur in a living organism in order to sustain life. Metabolism refers to the entire quantity of metabolic events involved in keeping cells alive in an organism. All living creatures require energy for several critical functions as well as the production of new biological molecules.


The metabolic processes help in the growth and reproduction and maintenance of living organisms’ structures. Because of metabolic activity, organisms respond to their surroundings. All chemical reactions in living organisms, from digestion to the movement of chemicals from cell to cell, require energy. Metabolism is a type of chemical process that occurs in our bodies and provides energy for various tasks. Simply put, we acquire energy from the foods and beverages we consume, and metabolism is the chemical process within our bodies that aids in the conversion of food into energy.

Metabolic Web

Cells are constantly performing millions of chemical reactions required to keep the cell and our body alive and healthy. These chemical processes are frequently connected in chains or pathways. A cell’s metabolic activity refers to all the chemical reactions that take place within it. Let us look at the metabolic diagram to gain a feel of the intricacy of metabolism. It depicts the key metabolic pathways in a eukaryotic cell, such as the cells that make up the human body. Each line denotes a reaction, and each circle is a reactant or a product.

Metabolic web

Some chemical reactions in the cell’s metabolic web release energy and can happen on their own (without energy input). Others, on the other hand, need greater energy. Cells require a constant influx of energy to fuel their energy-requiring chemical processes, just as you must eat food to replace what your body utilizes. In truth, the energy utilized by your cells is derived from the food you eat.


Breaking down Glucose: Cellular Respiration

In a cellular respiration process, many cells, including most of the cells in your body, obtain energy from glucose C6H12O6. A glucose molecule is progressively broken down in numerous little stages throughout this process. However, the total response of the process is:

Breaking down of glucose

The process of breaking down glucose releases energy, which the cell stores as adenosine triphosphate, or ATP. ATP is a small molecule that provides a simple technique for cells to temporarily store energy. Once created, ATP can be utilized as an energy source by other processes in the cell. Much like how we humans use money to avoid haggling every time we need something, the cell employs ATP to have a standardized manner of transferring energy. As a result, ATP is frequently referred to as the cell’s “energy currency.”

Building up Glucose: Photosynthesis

Photosynthesis is the process through which plants create carbohydrates such as glucose. During photosynthesis, plants use solar energy to transform carbon dioxide gas into sugar molecules. Photosynthesis occurs in numerous minor stages, but the overall reaction is simply the cellular respiration reaction reversed:

Cellular respiration

Plants require energy to operate their cellular operations; thus, the plant consumes part of the sugars. They can also supply food for animals that consume the plant, such as the squirrel shown in the figure. The glucose will be broken down by cellular respiration, creating ATP to keep the cells working in both circumstances.

Catabolic and Anabolic Pathways

Metabolic pathways include the processes of producing and decomposing glucose molecules. A metabolic route is a chain of chemical reactions that feed off one another. The route accepts one or more beginning molecules and transforms them into products through a series of intermediates.


Based on their impact, metabolic pathways may be split into two types. Photosynthesis, which creates sugars from smaller molecules, is an anabolic (building up) mechanism. On the other hand, cellular respiration is a catabolic (breaking down) function that breaks sugar down into smaller molecules.

Anabolic Pathways

Anabolic pathways generate complex molecules from simpler ones and often require energy input. The synthesis of glucose from carbon dioxide is one example. Other examples include the creation of proteins from amino acids and DNA strands from nucleic acid-building components (nucleotides). These biosynthetic activities are essential to cell survival, occur continuously, and require energy carried by ATP and other short-term energy storage molecules.

Catabolic Pathways

Catabolic pathways include the breakdown of complex molecules into simpler ones, which usually results in the release of energy. Catabolic processes release the energy trapped in the bonds of complex substances such as glucose and lipids. It is then collected in forms that can power the cell’s operations (for instance, through the synthesis of ATP).

Flow of Energy-Metabolism


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