What are Biomolecules? Their Types & Functions in the Body

Biomolecules are substances that are exclusively found in living organisms. Of these, there are four major biomolecules like

  1. Carbohydrates
  2. Proteins
  3. Fats and
  4. Nucleic acids.

These four are considered major as they are present in almost all the cells and tissues of living organisms, and without them, the biological system could be impossible.

Besides these, there are many minor biomolecules, as mentioned in the table below.

The biomolecules are formed by biological means and are responsible for the anatomy and physiology of plants, animals, and humans.

The list of biomolecules includes

BiomoleculeChemical Class (categories)Character and roleDistribution
Carbohydrates (Glucose)Carbohydrates.Sweet in taste & provides energy to the bodyAnimals & plants
(Amino acids)
ProteinsTo make up proteins and bodybuildingAnimals & plants
Oils & FatsLipidsReserve energy.Animals and plants
AcetoacetateKetone bodiesSource of energyAnimals
DNANucleic AcidRegulates Body composition & PhysiologyAnimals & Plants
RNANucleic AcidVitamins A, B, C, D, E & KAnimals & Plants
Cholesterolsteroids biomoleculesPrecursor for other moleculesAnimals
EnzymesProteinsAs catalysts to aid reactionsAnimals & plants
CortisolSteroid biomoleculeStress compatibilityHumans
HormonesAmides, lipids, aminesAct as messengers to regulate physiologyAnimals & plants
GumCarbohydrates in nature Metabolites that can swell with waterPlants
GlycosidesMade of carbohydrate + Glycoside moietyMetabolites are used in medicinePlants
TanninsMetabolitesWaste matter for plants but used by humansPlants
CholesterolLipidsForms cell membraneAnimals
Essential oilsHydrocarbons (volatile oil are gases at high temperatures.As metabolites to attract insects for pollination. Humans use them as perfumes.Plants
Vitamins A, B, C, D, E & KVitaminsTo aid in body physiologyAnimals & Plants

Other bio-molecules in the body include

  • Neurotransmitters
  • Hormones
  • Enzymes
  • Vitamins

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

Glucose molecule.

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

Amino acids


These are long-chain polymers of amino acids. These are the biomolecules having nitrogen along with carbon, hydrogen, and oxygen.

Amino acids are the basic units of proteins, and these molecules have amino and carboxylic groups in the same structure (zwitter ions).

They are involved in making the body’s cells and tissues. They are metabolized to ammonia and urea and excreted in the urine.


They have a long chain of fatty acids and glycerol linkage.

They are called glyceryl esters. They are stored in the body as reserve food, and during starvation, they form carbohydrates and give energy to the body.

Chemical structure of fatty acid molecule linked with glyceraldehyde.
Fatty acid molecule: Murraystate.edu

Nucleic acids

These molecules are found in the cell nucleus.

They are made of nuclear bases and ribose sugars with phosphodiesterase bonds.

There are two types: DNA and RNA.

DNA helps in the management of cell physiology through the production of RNA.

RNA helps in the formation of proteins, enzymes, and other required components of the body.

Nucleic acids RNA and DNA structure
DNA and RNA structure Image By Roland1952/wiki commons


As the name indicates, these are signal transmitters in the nervous system.

They help in the transmission of nerve impulses for the senses, motor effects, and the autonomic nervous system.

See more details on the list of neurotransmitters.


These are also signal transmitters in the body and are used to maintain body physiology.

There are many hormones in the body that control almost every aspect of living, like growth and even mood.


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.


These biomolecules are required in low quantities from food.

They, in most cases, are associated with enzymes to help in the body’s reactions. There are 5 types: Vit-A, B, C, D, E, and K.

Different types of biomolecules

What are biolmolecules

Biomolecules are of different types and can be classified as

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

Based on availability

Different types of biomolecules are available in different sets of organisms.

Not all the bio-molecules of plants are available in animals and vice-versa.

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

  1. plants
  2. animals
  3. Microbes.

Example: Lignin and chitin are biomolecules present only in plants in the plant cell wall.

While the same cell wall in bacteria is made of gluco-polysaccharides, gluco-peptides are present in the gram +ve bacterial cell walls.

At the same time, animals do not have a cell wall. Hence, there is a difference in the existence of biomolecules.

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

In animals, biomolecules like epinephrine and dopamine-like substances are specific.

Based on purpose

Further, these bio-molecules have different roles and purposes in the 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.

There are many biomolecules based on their role in the body.

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

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

Examples include Carbohydrates, proteins, fats, and vitamins.

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

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

Primary metabolites: These are the substances that act as intermediates in the body’s 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 the end metabolic substances. They are mostly excreted from the body through organs like kidneys.

Ex: Urea, uric acid, ketones, etc.

Biomolecules are the natural substances present from birth to death of living beings. They are synthesized in the body by the 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 they have elements like carbon and hydrogen, they are classified under organic compounds.

Importance of biomolecules

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

  1. Carbohydrates, proteins, and fats are used as foodstuffs in various forms.
  2. Volatile oils or essential oils are used for perfumes.
  3. Compounds like alkaloids, glycosides, and tannins are used in medicine.
  4. Tannins are also used for tanning (toughening) the leather in industry.

Besides, protein structure helps to understand receptors’ actions of drugs and hormones. At the same time, DNA structure helps to understand genetic disorders and any related abnormalities.

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

What biomolecules are used for energy

Carbohydrates like glucose and other monomers are mainly used for energy in the body.

However, during starvation, the body starts to use lipids stored as a source of energy.

In extreme starvation, even amino acids and other metabolites of the TCA cycle are also converted to carbs by the process of gluconeogenesis to generate energy.

What biomolecules are found in the cell membrane

The Cell membrane has a lipid bilayer, and it consists of proteins, lipids, and carbohydrates.

Which biomolecules contain nitrogen and phosphate

Nucleic acids, like DNA and RNA, are biomolecules that have both nitrogen and phosphorous.

Which biomolecule is responsible for insulation and energy storage

Fat is responsible for insulating (preventing) heat loss and storing excess energy from food.

Which biomolecule is a quick source of energy

Acetylacetone is a quick source of energy.

What type of biomolecules are enzymes

Enzymes are made of protein, so they can be classified under protein biomolecules.

What three elements are in all biomolecules?

Carbon, hydrogen, and oxygen are the elements found in all the biomolecules.


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