Metabolism Metabolic Pathways


Metabolism is a series of chemical reactions that occur in the living organism through which food and drinks change into energy. These chemical reactions are controlled by specific proteins present in the body. To keep our bodies healthy and working several number of reactions takes place at the same time. Two types of activities are involved in metabolisms i.e., anabolism and catabolism. The building of body tissue and storing of energy is called anabolism. The process by which breaking down large molecules and producing energy is called catabolism.

What is a Metabolic Pathway?

The metabolic pathway is the series of biochemical reactions that convert substrate molecules to end products through a series of metabolic intermediates. In a cell, these metabolic pathways are controlled by enzyme-catalyzed reactions.

  • Several number of metabolic pathways combine to form a complex network that is very essential to maintain life.

  • The metabolic pathways are controlled by the enzymes at each stage by changing the medium into the final product.

  • Almost all metabolic pathways are reversible.

  • If a specific enzyme or substrate is unavailable in a pathway, the final product can be still produced using another metabolic pathway.

  • Metabolic pathways are very important for our body.

Concept of Metabolism

Metabolism is the summation of all chemical reactions that occur in the cells of living organisms. There are two types of metabolism such as catabolism and anabolism.

  • Catabolism − It is the process of breaking down complex molecules into small ones. It releases energy during the reaction.

  • Anabolism − It is the process of building up complex molecules from smaller ones. This reaction requires energy.

The concept of metabolism is the usage of food for energy. Metabolism is very essential for all living organisms. During metabolism, the food or drinks we ate will undergo many changes, and biomolecules present in the food are converted into other molecules.

For example − When a person eats food that contains sugar, these sugar molecules will break down into simpler molecules with releases of energy once it reaches inside the body, and proteins are converted into amino acids by metabolism, and later it is used to produce other proteins.

The process of building and breaking down molecules takes place through a series of chemical pathways called metabolic pathways. All metabolic reactions are controlled by enzymes.

Examples of Metabolic Pathway

Some of the important examples of metabolic pathways are given below −

  • During the process of cellular respiration, glucose is oxidized with the use of oxygen and produces Adenosine Triphosphate (ATP).

  • Synthesis of large proteins from amino acid building block and new DNA strand from nucleic acid building block.

  • The process of building up and breaking down glucose molecules.

Purpose of Metabolic Pathway

The purpose of metabolic pathways is,

  • To release and store energy through a series of chemical reactions.

  • To remove or eliminate waste material and toxic products.

  • Metabolism provides energy that is essential for biological activity i.e., growth, reproduction, and structure of all living organisms.

Basic Metabolic Pathway

There are two main types of metabolic pathways. Such as the catabolic pathway and anabolic pathway.

Catabolic pathway

This pathway involves a series of biochemical reactions through which breaking down of the large molecules takes place releasing energy. This energy is utilized for cell functions and other reactions that take place in the body.

Examples of catabolic pathways are,


It is a ten step process through which one glucose molecule is converted into two pyruvate molecules. This process involves several chemical reactions. The products of one reaction are utilized for the substrate of the next reaction.

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Kreb cycle

It is a series of reactions that takes place in mitochondria to release stored energy. The pyruvate is derived from nutrients and is converted into Acetyl Coenzyme A. Then it is completely oxidized into carbon dioxide and water to produce an energy-rich phosphate compound. This is also known as the Citric acid cycle.

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Anabolic pathway

It is the series of biochemical reactions which build up large molecules from smaller ones. This reaction is building up materials together hence it needs energy.

Examples of catabolic reactions −

  • Synthesis of sugar from carbon dioxide.

  • synthesis of large proteins from amino acids building block.

  • Synthesis of new DNA from nucleic acid building block.

How to Increase Metabolism?

  • The protein-rich food increases the metabolism in the body. Eating food can increase our metabolism temporarily and this process is called the thermic effect of food. Protein will increase this effect of food. It also helps to prevent overeating.

  • Drinking more water boosts our metabolism.

  • Exercise and high-intensity workouts can also increase our metabolism.

  • We can increase metabolism by lifting heavy weights for muscle building. It helps for a higher metabolism.

  • Standing and walking will improve the metabolism instead of sitting too much.

  • Drinking green tea helps to improve metabolism.

  • Good sleep at night can boost our metabolic rate.


  • The series of chemical reactions that occur in the cells of living organisms is called Metabolism.

  • The process of breaking down complex molecules into small ones and releasing energy during the reaction is called catabolism.

  • The process of building up complex molecules from smaller ones with the use of energy is called anabolism.

  • A metabolic pathway is the network of a series of chemical reactions to convert substrate into end product through several metabolic intermediates.

  • Two types of basic metabolic pathways: The catabolic pathway and the Anabolic pathway.

  • Metabolism provides and stores energy.


Q1. What is Gluconeogenesis?

Ans. The process of transformation of non-carbohydrate dietary intake into glucose. This provides energy for other life processes occurring inside the body.

Q2. What do you mean by endergonic reactions?

Ans. The reactions which require free energy to proceed are endergonic reactions. For example, the melting of ice.

Q3. What is the difference between anabolic and catabolic pathways?

Ans. The catabolic pathway involves breaking down large molecules by releasing energy. In the anabolic pathway, the building up of large molecules with help of energy.

Q4. Write any two methods to increase metabolism.

Ans. Drinking more water and green tea will help to increase metabolism and good sleep at night can also boost metabolism.

Q5. What do you mean by the thermic effect of food?

Ans. The process of increase in metabolic rate after eating food is called the thermic effect of food (TEF).

Updated on: 09-Jan-2023


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