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What are Biomolecules?

Biomolecules are the primary building blocks of every living organism. Together, they promote different biological processes, which are necessary for life. They vary in structures and sizes. Biomolecules primarily consist of hydrogen and oxygen. 

The living systems synthesize four primary types of biomolecules within the body. They are:

  • Carbohydrates

  • Proteins

  • Fats

  • Nucleic Acids

With biomolecules definition, it is also important to know that the major types of biomolecules are basically polymers of simple elements. For example:

  • Amino acids form the basis for proteins.

  • Phosphate, sugar, and nitrogen for nucleic acids.

  • Fatty acids and glycerol for lipids.

  • Simple sugar for carbohydrates.

Some biomolecules can also be combined to get specialized molecules. For example:

  • Protein and carbohydrate in glycoproteins

  • Protein and lipid in lipoproteins

  • Lipid and carbohydrate in glycolipids

Different Types of Biomolecules

Apart from the major biomolecules like carbohydrates, protein, fat and nucleic acids, classification of biomolecules should also involve the mention of smaller biomolecules like natural products, as well as primary and secondary metabolites. 

The Details of the Major Types of Biomolecules are Discussed as Follows:


It contains a combination of carbon, hydrogen, as well as oxygen. They are present in the ratio of CnH2N. Since sugar is the most fundamental component of almost all types of carbohydrates, they are also called saccharides (as in Greek, sakcharon refers to sugar). Photosynthesis is the primary source of carbohydrates. Almost 80% of a plant’s dry weight is owing to the carbohydrate content in its body. 

Examples of carbohydrates include plant starch, animal starch or glycogen, sugar and cellulose. Carbohydrates can further be subdivided into four types. Monosaccharides: They are the polyhydroxy ketones or Polyhydroxy aldehydes that do not break into simpler carbohydrate molecules. Examples include Gulose, Ribose, Glucose, Mannose, Arabinose, Fructose, and the like. Trisaccharides: On hydrolysis, these can give three molecules of monosaccharide. For example, Raffinose (C18H32O16). Oligosaccharides: By means of hydrolysis, these carbohydrates can be broken into 2-9 molecules of monosaccharides. Polysaccharides: They have higher molecular weight and can be split into a number of monosaccharide modules, upon hydrolysis. Example, Cellulose and starch, both having identical molecular formula, that is (C6H10O5)n.


Almost 15% of the ‘living’ portion of any cell, or its protoplasm, comprises protein. On an average, every molecule of protein comes with 50–55% carbon, 20–24% oxygen, 16% nitrogen, 7% hydrogen and 0.3 – 0.5% sulphur, along with traces of phosphorus, iron, calcium, iodine and copper. 

Different types of proteins have different biomolecules structures. This is because of the variation in the amino acid, which are the organic compounds that combine to form protein molecules. A string of peptides again forms unique peptide bonds. The different types of peptides include polypeptide, tripeptide and dipeptide. Proteins are categorized on the basis of their constitution, shape and functionalities. For example, as per their constituents, proteins can be divided into simple and conjugated protein. As per their shapes, proteins are classified as Scleroprotein/ Fibrous protein and Globular Protein. As per their molecular nature, protein can be divided into Acidic Proteins and Basic Proteins.


Lipids are basically esters of alcohol and fatty acid. Lipids can be categorized as the Simple lipids, compound lipids and derived lipids. Simple lipids are the esters of glycerol and fatty acid. They can be subdivided as first Fats and oils, second Fatty Acids- These are again of two types. They include Saturated Fatty Acid and Unsaturated Fatty Acid, third Waxes. Compound Lipids come with an additional element with alcohol and fatty acid. The subtypes include Phospholipids, Chromolipids, Glycolipids and Aminolipids. Derived lipids derived from the hydrolysis of both simple and compound lipids.

Nucleic Acids

It is a term used to collectively refer to DNA and RNA. The size of these biomolecules varies in different organisms. They are made from nucleotides. These compounds have any of the four chemicals Guanine, Thymine, Adenine or Cytosine as a base, starch and phosphate. Nucleic acids vary in their properties, functionalities, structure and even in their location in the cell. The different types of nucleic acids include DNA and RNA. Deoxyribonucleic Acid or DNA is a very significant biological molecule, which has its presence in the living part of the cells. The genetic information of any cell is kept stored as DNA. Ribonucleic acid or RNA is a polymer of ribose, as well as pentose sugar. DNA and RNA work together for most organisms.

Here are the answers to some of the most frequently asked questions regarding the different types of biomolecules.

Last updated date: 26th Sep 2023
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FAQs on Biomolecules

1. What are the 4 Biomolecules and their Function?

Carbohydrates, Proteins, Lipids and Nucleic Acids are the 4 biomolecules. Carbohydrates are the source of energy. Proteins do all essential functions like immunity, general metabolism etc. Lipids are like a greater source of energy, and work as energy storage. Nucleic Acids are genetic material and also determine protein synthesis. 

2. What are Saturated Fatty Acids?

These fatty acids don't contain a double bond between the atoms of carbon. Examples include palmitic acid, butyric acid and hexanoic acid. They are sub-categorized as short-chain fatty acids, medium chain fatty acids, long chain fatty acids and very-long chain fatty acids. Common sources of such fatty acids are coconut and palm oil, dairy fat, peanuts, dry fruits, fibers, lauric acid, acetic acid etc. In saturated fatty acids, the hydrocarbon chain is straight and contains only single bonds. It has low rancidity and high shelf life. In a human body, 10% of the calories should come from saturated fatty acids. They are healthy (if consumed in proper quantity) but excess consumption can lead to heart attack and other diseases. 

3. What are Unsaturated Fatty Acids?

They have double bonds in the atoms of carbon. They are primarily found in plant fats. Examples include Octadecanoic acid and Hexadecanoic acid. These can also be found in avocados, canola oil, sunflower oil, fish oil, olive oil etc. It has low melting points and is liquid in state. They have bent hydrocarbon chains. Unsaturated Fatty Acids are highly rancid in nature and has low shelf life. These substances decrease the LDL. In a human body, 30% should come from the unsaturated fatty acids. It's excessive consumption can reduce the cholesterol level in the body. Therefore, a balanced use of saturated and unsaturated fatty acids is necessary for a healthy daily life. 

4. What is Phospholipid?

These types of lipids contain phosphoric acid. It provides good flow to the blood. They help to improve overall metabolism, aids in the transportation of nutrients, enhances blood clotting mechanism and promotes the porousness of cell membrane. Nowadays, nanotechnology and materials science uses commercially produced Purified phospholipids for various applications. These can be industrially produced by sources like soya, sunflower, bovine milk, chicken eggs, rapeseed, fish eggs etc.

Therefore, Phospholipids have many different applications in fields like pharmaceuticals, nutrition, food etc. 

5. What is Glycolipid?

Apart from fatty acids, they contain carbohydrate and nitrogen molecules. They are primarily present in the White Matter of the brain and overall nervous system. These biomolecular structures are responsible for cellular recognition and contribute to proper immunological functions. 

6. Differentiate Between Oligosaccharides and Monosaccharides, as well as Polysaccharides.

The following points of difference between Oligosaccharides and Monosaccharides, as well as Polysaccharides are as follows :

(i) Monosaccharides cannot be hydrolysed further but Oligosaccharides and Polysaccharides can be further hydrolysed to obtain 

(ii) Monosaccharides and oligosaccharides are crystalline solid in nature whereas polysaccharides are amorphous. 

(iii) Monosaccharides and oligosaccharides are sweet in taste whereas polysaccharides are tasteless. 

(iv) Monosaccharides and oligosaccharides are also termed as 'sugar' whereas polysaccharides are also called 'non-sugar' .

(v) Monosaccharides and oligosaccharides  are water soluble whereas polysaccharides are water insoluble. 

7. What are Esters?

In terms of biology, esters refer to an organic molecule, which is generated after a combination of an acid with an alcohol. The process is done by removing water from both elements. This process is generally known as 'esterification'. Esters are commonly found everywhere (are ubiquitous). Esters are used as fragrances if they have low molecular weight . They are also added in essential oils.

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