Major Molecules in Biochemistry


Carbohydrates, lipids, proteins, and nucleic acids are the four primary types of molecules found in food. These molecules are referred to as polymers or macromolecules. They are composed of tiny molecules, or monomers, that are joined to create polymers. Through the use of enzymes, monomers are joined to create biological polymers.


The most prevalent and plentiful organic substance on earth is a carbohydrate. They are crucial to both plants and animals’ metabolisms. All other species that rely on the consumption of organic substances with food are based on the production of carbohydrates in plants from carbon dioxide and water with the aid of light energy (photosynthesis).

Functions: Through their oxidation in the tissues, they serve as the primary source of biological energy. They also provide the organic building blocks needed for the production of several cell components.

Sources: Compared to diets high in fat and protein, carbohydrates are more prevalent and less expensive. Food carbohydrates are starches and sugars that may be found in milk and milk products, vegetables, legumes, fruits, cereal grains, and tubers. Glucose may be found in honey. Although it has no metabolic function, fibre, which is mostly composed of cellulose and other indigestible cell-wall polymers of plant origin, aids in maintaining healthy intestinal movement.


Lipids are compounds that are found in food and include fats, oils, and substances that resemble fat. They are a different class of significant molecules present in all cells. Compared to other types of biological compounds, lipids have a wider range of structural variations.

Functions: They are crucial elements of cellular membranes, forming lipid bilayers. Lipids with hydrocarbon chains function as energy reservoirs. Lipid molecules are involved in several intra- and intercellular signalling processes. Along with triglycerides, cholesterol and phospholipids also provide bodily cells shape.

Sources: Meat, milk, eggs, and fish are key animal sources of fat, whereas all oils and vanaspati are significant plant ones. Saturated fatty acids are generally abundant in animal-based fats, whereas polyunsaturated fatty acids are few. Polyunsaturated fatty acids are prevalent in fish and plant lipids.

Meat, butterfat, egg yolks, and other animal products all contain large quantities of cholesterol. Plant foods don’t have it.


All cells have a high concentration of proteins, which make up around 50% of a cell’s total mass. An unbranched polymer of amino acids is a protein.

Functions: The necessary amino acids are provided by proteins as the basis for protein production. The building blocks of many different nitrogen-containing biomolecules, including enzymes, hormones, porphyrins, and many more, are amino acids. A sizeable portion of the daily energy demand is also provided by the oxidation of the carbon skeletons of amino acids. They are precursors of the fragrance compounds and colours created during thermal or enzymatic processes during food manufacturing, processing, and storage, and they also contribute to the flavour of food.

Sources: Important sources of protein include meat, fish, milk, eggs, lentils, beans, and peas.

Nucleic acids

Nucleotide monomers make up the polymers that make up nucleic acids. The nucleotides consist of a phosphate group, a heterocyclic nitrogenous base, and a five-carbon sugar (s). Covalent bonds between the phosphate of one and the sugar of the other are what hold them together. These connections are known as phosphodiester links.

Deoxyribonucleic acid (DNA) and ribonucleic acid are the two forms of nucleic acids that are present in cells (RNA).

The cell nucleus is where the majority of the DNA is located. It serves as a reservoir for inherited character. RNA is present throughout a cell. In essence, it is necessary for protein production.


The storing and transmission of genetic data is DNA’s main purpose. Many of a live cell’s operations are (indirectly) controlled by this information. Furthermore, DNA is transferred from old to new cells during cell division. RNA predominantly contributes to the creation of proteins, which are the molecules responsible for carrying out vital biological processes.

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