What are biomolecules? 4 Different Types & their Functions

What are biolmolecules

These are the substances which are present exclusively in the living organisms.

They are formed in the body by biological means and manage the physiology and growth.

There are many biomolecules in nature and one can read them in detail in biochemistry.

Biochemistry describes their formation, physiological role and any deficiency diseases.

The biomolecules are present in the body of humans, animals and plants.

Their primary formation from the basic elements seems to occur in plants.

Once formed, these molecules then pass on to animals through the food chain.

If you wish to directly go through list of biomolecules, you can refer to table at the bottom of the article.

Different types of biomolecules:

Biomolecules are of different types and can be classified asWhat are biolmolecules

  1. Based on availability or source.
  2. Based on their role or purpose in body.
  3. Based on their chemistry (i.e. bonds and functional groups).

Based on availability: Different types of biomolecules are available in different set of organisms. Not all the bio-molecules of plants are available in animals and vice-verse.

Hence based on the availability they can be divided as those available in

  1. plants
  2. animals
  3. Microbes.

Example: Lignin, chitin are biomolecules present only in plants in plant cell wall. While the same cell wall in bacteria is made of  gluco-polysacharrides gluco-peptides are present in bacterial cell wall. While animals do not have a cell wall. Hence there is difference of existence of biomolecules.

Besides these plants have alkaloids, glycosides, tannins, resins, gums etc. which are specific to them.

In animals biomolecules like epinephrine, dopamine like substances are so specific.

Based on purpose: Further these bio-molecules have different role and purpose in body. So their existence in this manner is solely dependent on the purpose.

Ex: Hemoglobin is a protein molecule formed in combination with iron (heme). It is  meant for oxygen supply to the body tissues. It is available only in animals and humans. But absent and also not needed for plants and microbes.

Though there are many biomolecules based on their role in body.

There are 4 types of bio-molecules as.

  1. Food sources.
  2. Body elements
  3. Primary metabolites
  4. Secondary metabolites.

Food sources: These are the substances which act as food materials. They give energy and nutrients to all the living beings on the earth.

Examples include: Carbohydrates, proteins, fats, vitamins.

Constitutional (Form Body) : These are the molecules which make up the body structure. They also tend to control the body physiology.

Examples include: DNA, RNA, steroids, cholesterol etc. DNA forms the genes and also mRNA, RNA from the body proteins. Steroids are part of many hormones.

Primary metabolites: These are the substances which act as intermediates in the body metabolism and other reactions. They are formed from one or other bio-molecules like food based or constitutional based.

Ex: UDP-Glucuronic acid, keto-glutaric acid etc.

Secondary metabolites: These are mostly end metabolic substances. They are mostly excreted from the body through organs like kidneys.

Ex: Urea, uric acid, ketones etc.

Biomolecules are the natural substance present from birth to death of living being. They are synthesized in the body by use of different elements from nature. Substances like carbon-dioxide, ammonium, water and other inorganic elements from soil contribute to the chemical formation of these molecules. Since some of them are formed by elements like carbon, hydrogen they are classified under organic compounds.

List of biomolecules:

In a simple worksheet explaining characters, role and availability.

GlucoseCarbohydrates.Sweet in taste & provides energy to bodyAnimals & plants
Sucrose (sugar) CarbohydratesSweet in taste & provides energy to bodyAnimals & Plants
Starch CarbohydratesBreaks down to sugarsAnimals & plants
Cellulose CarbohydratesBreaks down to sugars & eaten by animalsPlants
DNANucleic AcidRegulates Body composition & PhysiologyAnimals & Plants
RNANucleic AcidProtein synthesis & physiologyAnimals & Plants
Amino acidsProteinsTo make up proteins and body buildingAnimals & plants
EnzymesProteinsAs catalysts to aid reactionsAnimals & plants
HormonesAmides, lipids, aminesAct as messengers to regulate physiologyAnimals & plants
GumsCarbohydrates in naturePlants
GlycosidesMade of carbohydrate + Glycoside moietyMetabolites but are used in medicinePlants
TanninsMetabolitesWaste matter for plants but used by humansPlants
CholesterolLipidsForms cell membraneAnimals
Essential oilsHydrocarbons (volatile oil which are gases at high temperature.As metabolites. To attract insects for pollination. Humans use as perfumes.Plants
Vitamins A,B,C,D,E & KVitaminsTo aid in body physiologyAnimals & Plants

This is not the end of the list but a brief categorization of biomolecules.

But of all those available, only 4 important biomolecules are studied widely.

These 4 major biomolecules include

  1. Carbohydrates.
  2. Proteins (amino-acids)
  3. Fats
  4. Nucleic acids (DNA, RNA, nucleotides).

Other bio-molecules in the body include

  • Neurotransmitters
  • Hormones
  • Enzymes
  • Vitamins

Carbohydrates are those which have aldehyde or ketone groups with CH2O configuration.


Glucose: A carbohydrate

They are obtained from food and used to generate energy in the body. They break down to carbon dioxide and water.

Proteins are long chain polymers of amino acids. Amino acids are molecules which have both amino and carboxylic groups on the same structure (zwitter ions).amino-acidThey are involved in making of the body cells and tissues. They are metabolized to ammonia and urea and excreted in urine.

Fats have a long chain of fatty acids and glycerol linkage. They are called as glyceryl esters. They are stored in the body as reserve food and during starvation, they form carbohydrates and give energy to the body.

Image: Murraystate.edu

Nucleic acids are the molecules formed in the nucleus. They are made of nuclear bases and ribose sugars with phosphodiesterase bonds. They are of two types as DNA and RNA. DNA helps in management of cell physiology by production of RNA. RNA helps in formation of proteins, enzymes and other required components of body.

Image By: Roland1952/commons.wikimedia.org

Neurotransmitters: As the name indicates, these are signal transmitters in the nervous system. See more details on list of neurotransmitters.

Hormones: These are also signal transmitter in the body and used to maintain body physiology. They are quite many hormones in the body and control almost every aspect of living being growth and even mood.

Enzymes: These are biocatalysts in the body. Like hormones they are also secreted by glands. Enzymes help in many reactions. See the types of enzymes and their reactions for more details.

Vitamins: These are bio molecules which are taken in extremely low quantities from food. They in most cases are associated with enzymes to help in the body reactions. They are 5 types like Vit-A, B, C, D, E and K.

Importance of biomolecules:

Biomolecules are used for different purposes like food, medicine, cosmetics etc. by humans. Below are few uses of them

  1. Carbohydrates, proteins, fats are used as food stuffs in various forms.
  2. Volatile oils or essential oils are used for perfumes.
  3. Compounds like alkaloids, glycosides, tannins are used in medicine.
  4. Tannins are also used to tan (toughen) the leather in industry.

Besides, protein structure helps to understand receptors, action of drugs and hormones. While DNA structure helps to understand genetic disorders and any related abnormalities.

These biomolecules are vital to the living beings. But they can be harmful and toxic if misused or over stagnated in the body.


  1. Ashish Jain
  2. katherien mary
  3. Momanyi Dennis Nyambane

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