Biomolecules

Biomolecules

Edited By Irshad Anwar | Updated on Jun 06, 2025 04:18 PM IST

Biomolecules are organic compounds that occur in all living things and are vital to structure, function, and metabolism. The four major biomolecules, proteins, carbohydrates, lipids, and nucleic acids, are responsible for essential life processes, including energy production, cell structure, and genetic information. Glucose, for example, yields 36–38 ATP per molecule of glucose during aerobic respiration, and proteins comprise more than 50% of a cell's dry mass. Lipids provide 9 kcal/g of energy and serve as the structural basis of cell membranes.

This Story also Contains
  1. What are Biomolecules?
  2. Types of Biomolecules
  3. Carbohydrates
  4. Proteins
  5. Lipids
  6. Nucleic Acids
  7. Vitamins and Coenzymes
  8. Functions of Biomolecules
  9. Synthesis and Breakdown of Biomolecules
  10. Disorders Related to Biomolecule Metabolism
  11. Recommended Video on Biomolecules
Biomolecules
Biomolecules

Nucleic acids such as DNA and RNA contain the genetic information of life, and the human genome comprises more than 3 billion base pairs. Enzymes, proteins, can catalyse millions of reactions per second, evidencing their biological efficiency. Carbohydrates are the source of dietary energy and contribute 50–60% of energy intake. These biomolecules interact with each other in a complex manner, and their understanding is central to medicine, Nutrients, and biotechnology.


Important Topics of Biomolecules:

Important topics in the chapter Biomolecules are the structure and functions of carbohydrates, proteins, lipids, and nucleic acids. Important concepts such as enzyme action, biomolecules' classification, and their biological importance are discussed too. Knowing the kinds of metabolism, catabolism, and anabolism is also very important. Some of the important topics are mentioned below:

  • Types of Biomolecules

  • Functions of Biomolecules

  • Biomolecules in Health and Diseases

  • Important Concepts - Proteins, Carbohydrates, Lipids, Nucleic Acids, Enzymes

Also Read:

What are Biomolecules?

Biomolecules are organic compounds found in the human body, playing a major role in both structure and function. The types of biomolecules include proteins, carbohydrates, lipids, nucleic acids, vitamins, and minerals. Carbohydrates and lipids are available for energy production and storage, while nucleic acids such as DNA and RNA carry genetic information. Biomolecules are also important for enzyme activity, cell signalling, transport, and communication throughout the body.

Types of Biomolecules

Biomolecules are needed by the body to perform different life processes. The various types of biomolecules are listed below:

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. Usually, the preferred ratio in this aspect is 2:1. They can be and often are simple sugars, but can also be complex polysaccharides. Sugar and starch are basic forms of Carbohydrates. They are responsible for providing energy and also help in building the cell walls of the cell. Carbohydrates can be simple, like glucose or complex, like starch.

Types of Carbohydrates

Different types of carbohydrates are discussed below:

Type of CarbohydrateNo. of Sugar UnitsExample(s)Description
Monosaccharides1 unitGlucose
  • Simple sugar
  • Basic unit of carbohydrates.
Disaccharides2 unitsSucrose (Glucose + Fructose)
  • Formed by linking two monosaccharides.
Oligosaccharides2–10 unitsRaffinose
  • Contains a few monosaccharide units
  • Not as large as polysaccharides.
PolysaccharidesMore than 10 unitsStarch, Cellulose
  • Large, complex carbohydrates are made of many monosaccharide units.


Functions of carbohydrates

Some of the major functions of carbohydrates are discussed below in the table:

FunctionDescription
Primary Source of EnergyProvides quick energy through glucose for body and brain functions.
Energy StorageExcess glucose is stored as glycogen in the liver and muscles for later use.
Sparing Protein UsePrevents proteins from being used for energy, preserving them for body repair.
Fat MetabolismHelps in the complete oxidation of fats and prevents ketone body formation.
Structural RoleForms part of DNA (deoxyribose) and RNA (ribose), essential for the genetic code.
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Examples of Carbohydrates

Some of the examples of carbohydrates include glucose, a monosaccharide; starch, a polysaccharide that acts as an energy store in plants; and cellulose, another polysaccharide found in the cell walls of plants as a structural component.

Proteins

Proteins can be described as large biomolecules that are created from Amino acids that are joined by peptide bonds to form structures with great complexity and intricacy regarding their shape. Proteins are made up of amino acids, and they are responsible for functions like building body structure and speeding up the reactions taking place in different processes.

They work as catalysts and are responsible for determining the shape of how they work. Sometimes they also work as enzymes. Protein is also known as an amino acid polymer because it is made up of organic compounds, which are amino acids, and 20 different types of amino acids play a role in the protein variant.

Types of Proteins based on structure and composition

Some major types of protein and their structure and composition are discussed below:

Type of ProteinStructure/CompositionExample(s)Description
Simple ProteinsMade of only amino acidsAlbumin, Globulin
  • Yield only amino acids on hydrolysis
  • no non-protein part.
Conjugated ProteinsProtein + non-protein partHemoglobin (protein + heme group)Contain a prosthetic group like metal ions, lipids, or carbohydrates.
Fibrous ProteinsLong, thread-like structureKeratin, Collagen
  • Provide structural support
  • insoluble in water.
Globular ProteinsSpherical, compact structureEnzymes, Antibodies
  • Functional proteins
  • Soluble in water and performs metabolic functions.
Derived ProteinsFormed from the breakdown of proteinsPeptones, ProteosesProducts of partial hydrolysis of simple or conjugated proteins.


Functions of Protein

Protein is involved in enzymatic activities, as hormones, in the structure and shape of the cells, and acts in immune defence too. Some major functions are discussed below in the table:

FunctionDescription
Structural SupportProteins like collagen and keratin provide strength and structure to tissues.
Enzymatic ActivityEnzymes (which are proteins) catalyse biochemical reactions in the body.
TransportProteins like haemoglobin transport oxygen
Others help carry nutrients.
Defense MechanismAntibodies (immunoglobulins) are proteins that help fight infections.
Hormonal RegulationSome hormones, like insulin and glucagon, are proteins that regulate metabolism.


Examples of Protein

Some of them include haemoglobin in the transportation of oxygen, Keratin, a structural protein present in hair and nails, and insulin, a hormone that helps regulate blood sugar.

Lipids

Lipids include compounds soluble in nonpolar solvents, they contain a large number of carbon-hydrogen atoms in long chains or the form of rings. Lipids are responsible for storing fats and oils. It is also important because it is a form of storage of energy, and it also forms the cell membrane of the cell. Lipids are also important for processes like sending signals from one cell to another. They are generally insoluble and can be both saturated and unsaturated fats.

Types of Lipids

Triglycerides act as energy storage or fat, phospholipids are part of cell membranes, and steroids include cholesterol, which is a hormone.

Type of LipidStructure/CompositionExample(s)Description
Simple LipidsEsters of fatty acids with alcoholsFats (triglycerides), Oils, WaxesComposed of glycerol and fatty acids,
They serve as energy reserves and insulation.
Compound LipidsLipids + additional groupsPhospholipids, GlycolipidsContain other groups like phosphate or sugar,
Major components of cell membranes.
Derived LipidsHydrolysis products of simple/compound lipidsSteroids (cholesterol), Fatty acidsObtained from the breakdown of simple or compound lipids involved in hormone synthesis.
SteroidsFour fused carbon ringsCholesterol, TestosteroneFunction as hormones, vitamins, and cell membrane components.
WaxesEsters of long-chain fatty acids & alcoholsBee wax, LanolinProvide protective coatings in plants and animals, water-repellent.


Functions of lipids

Lipids are involved in energy storage, determination of membrane fluidity plays a role in signal transduction. Some of the major functions of lipids are discussed below:

FunctionDescription
Energy StorageLipids store energy efficiently, providing 9 kcal/g, more than carbohydrates or proteins.
Structural ComponentPhospholipids form the basic structure of cell membranes (lipid bilayer).
Insulation and ProtectionLipids insulate the body and protect vital organs by cushioning them.
Hormone SynthesisCholesterol is a precursor for steroid hormones like estrogen and testosterone.
Fat-Soluble Vitamin AbsorptionLipids help in the absorption of vitamins A, D, E, and K.


Examples of Lipids

Usual lipids are the fats and oils (triglycerides), phospholipids that set up cell membranes, and sterol–cholesterol.

Nucleic Acids

Nucleic acids can be defined as large biomolecules that are made up of a chain of nucleotides. A nucleotide is a molecule that has both a sugar as well as a phosphate group and contains a nitrogenous base. Nucleic acids are responsible for storing genetic information. DNA and RNA are made up of nucleotides and are two of the best compounds to carry genetic information. DNA carries long-term genetic data, while RNA helps the formation of different types of protein in the body.

Types of Nucleic Acids

Major types of nucleic acids are discussed below in the table:

Type of Nucleic AcidStructure/CompositionExample(s)Description
DNA (Deoxyribonucleic Acid)Double-stranded polymer of nucleotidesHuman DNA
  • Stores genetic information composed of deoxyribose sugar, phosphate, and bases.
RNA (Ribonucleic Acid)Single-stranded polymer of nucleotidesmRNA, tRNA, rRNA
  • Involved in protein synthesis
  • contains ribose sugar instead of deoxyribose.
NucleotidesNitrogenous base + pentose sugar + phosphateATP (adenosine triphosphate)
  • Building blocks of nucleic acids
  • ATP stores and transfers energy in cells.
NucleosidesNitrogenous base + pentose sugarAdenosine, CytidinePrecursors of nucleotides, lacking a phosphate group.
Other Nucleotide DerivativesModified nucleotides involved in signallingcAMP (cyclic AMP), NAD⁺Important in cellular signalling and metabolic reactions.


Functions of Nucleic Acids

Nucleic acids are involved in the replication of genetic data and also in the synthesis of proteins, and the transmission of heredity. Some major ones are discussed below in the table:

FunctionDescription
Genetic Information StorageDNA stores the hereditary genetic code that controls cell function and inheritance.
Protein SynthesisRNA helps translate genetic information into proteins via mRNA, tRNA, and rRNA.
Energy TransferATP, a nucleotide, stores and transfers energy within cells for metabolic processes.
Cell SignalingMolecules like cAMP act as secondary messengers in cellular communication.
Regulation of MetabolismNucleotides like NAD⁺ and FAD participate in oxidation-reduction reactions in metabolism.


Examples of Nucleic Acids

DNA and RNA, where DNA is the carrier of the code and RNA takes part in the code implementation.

Vitamins and Coenzymes

Some of the small organic molecules that help the enzymes to do their job in the chemical reactions are known as coenzymes. These are responsible for the overall metabolic speed and the metabolism of our body.

Types of Vitamins and Coenzymes

Some of the major types of vitamins and coenzymes are discussed below:

TypeStructure/CompositionExample(s)Description
Fat-Soluble VitaminsOrganic compounds soluble in fatsVitamins A, D, E, and KStored in body fat, involved in vision, bone health, antioxidant functions, and blood clotting.
Water-Soluble VitaminsOrganic compounds soluble in waterVitamin B-complex, Vitamin C
  • Not stored in large amounts
  • They act mainly as coenzymes in metabolism and antioxidant roles.
CoenzymesNon-protein organic molecules derived from vitaminsNAD⁺ (from Niacin), FAD (from Riboflavin)Helps enzymes in catalysing biochemical reactions by transferring chemical groups.
ProvitaminsPrecursors are converted into active vitaminsBeta-carotene (Vitamin A precursor)Converted by the body into active vitamins as needed.
Mineral-based CoenzymesInorganic ions that help enzyme functionZinc, Magnesium
  • Essential for the catalytic activity of some enzymes
  • They act as cofactors alongside coenzymes.


Functions of Vitamins and Coenzymes

Some of the major functions of vitamins and coenzymes are discussed below in the table:

FunctionDescription
Enzyme ActivationCoenzymes derived from vitamins help enzymes catalyse metabolic reactions efficiently.
Antioxidant ProtectionVitamins like C and E neutralise free radicals, protecting cells from oxidative damage.
Bone and Vision HealthVitamin D aids calcium absorption for bones.
Vitamin A is essential for vision and eye health.
Immune Function SupportVitamins like C and A boost immune responses and help fight infections.
Blood Clotting and HealingVitamin K is necessary for blood clotting.
B-complex vitamins support wound healing processes.


Examples of Vitamins and Coenzymes

Examples of Vitamins: Vitamin A (retinol), Vitamin C (ascorbic acid), Vitamin D, Vitamin E, Vitamin K, and B-complex vitamins such as B₁ (thiamine), B₂ (riboflavin), B₃ (niacin).

Examples of Coenzymes: NAD⁺ (derived from niacin), FAD (derived from riboflavin), Coenzyme A (derived from pantothenic acid), and TPP (derived from thiamine).

Functions of Biomolecules

Some important functions of Biomolecules are discussed below:

Function

Explanation

Energy Storage

  • Carbohydrates and lipids are responsible for storing energy for all the processes taking place inside the cell.

  • Carbohydrates are also a form of short-term energy, while lipids are responsible for long-term energy storage.

Structural Support

  • Protein and carbohydrates are responsible for supporting and maintaining the structure of tissues and cells.

  • Lipids also play a very important role in forming cell membranes due to the presence of phospholipids.

Catalysis

  • Enzymes, such as proteins, act as catalysts to speed up the cellular reactions taking place during different processes, such as digestion and metabolism.

  • For example, in carbohydrate metabolism, an enzyme known as amylase that helps in the breakdown of carbohydrates is a significant function of enzymes in metabolism.

Genetic Information

  • DNA and RNA are responsible for storing nucleic acids, transmitting and then expressing them into genetic information.

  • DNA contains the hereditary material, while Ribosomes and RNA transcribe this information to manufacture proteins, thus playing the role of heredity and cell functions.

  • This makes sure that all the traits are packed in the form of protein and are synthesised when needed.

Cell Communication

  • Proteins and lipids are responsible for cell signals and communication between cells.

  • There are certain hormones which are made up of proteins and lipids and help regulate different body processes.

  • The receptors of these hormones are present on the cell membrane where they receive signals.

Regulation and Coordination of Biological Processes


  • These are chemical substances that control and synchronise different functions of the body

  • Most of them are proteins or lipids.

  • Insulin is a protein hormone that regulates glucose concentration in the bloodstream to maintain normal concentration within the body.


Synthesis and Breakdown of Biomolecules

There are two pathways for a breakdown of Biomolecules. Both of process of synthesis and breakdown of biomolecules is discussed below:

AspectAnabolic PathwaysCatabolic Pathways
DefinitionBiosynthetic processes that build larger molecules from smaller ones.Degradative processes that break down large molecules into simpler ones.
Energy RequirementRequires energy input (endergonic).Releases energy (exergonic).
Molecules InvolvedBuilds macromolecules like proteins, nucleic acids, and polysaccharides.Breaks down macromolecules like carbohydrates, fats, and proteins.
PurposeSupports growth, repair, and storage.Provides energy (ATP) for cellular activities.
ExampleSynthesis of proteins from amino acids.Breakdown of glucose in cellular respiration to produce ATP.


Enzymatic Reactions in Synthesis and Degradation

Catalytic actions of enzymes are involved in biosynthesis as well as the degradation of biomolecules. As such, enzymes facilitate metabolic reaction processes by increasing the rate of such processes.

For example, the specific enzymes DNA polymerase are used to synthesise DNA and proteases are used to deconstruct proteins into amino acids.

Examples of Metabolic Pathways

Major example of Metabolic Pathways are discussed below in the table:

ProcessTypeKey StepsEnd ProductsFunction
GlycolysisCatabolicBreakdown of glucose into pyruvate in the cytoplasm2 Pyruvate, 2 ATP, 2 NADHThe initial stage of cellular respiration
Provides energy and metabolic intermediates.
Krebs CycleCatabolicOxidation of pyruvate-derived acetyl-CoA in mitochondriaATP, NADH, FADH₂, CO₂Generates energy carriers (NADH, FADH₂) for the electron transport chain.
Protein SynthesisAnabolicTranscription (DNA → mRNA) and translation (mRNA → protein)Functional proteins (polypeptides)Builds proteins necessary for structure, enzymes, and cell function.


Role of Biomolecules in Maintaining Health

Biomolecules are involved inter alia in the regulation of physiological processes leading to a complex organism’s homeostasis and health condition. They include carbohydrates that supply energy, proteins required for tissue building and enzymatic processes, lipids that are useful in the formation of cell membranes and for energy storage, and nucleic acids that contain stored hereditary material.

Disorders Related to Biomolecule Metabolism

Some common disorders related to biomolecule metabolism are:

DisorderCauseEffect on MetabolismHealth Impact
DiabetesLack of insulin (Type 1) or reduced insulin sensitivity (Type 2)Impaired glucose absorption and utilisation
high blood sugar levels
Leads to fatigue, vision issues, nerve damage, and long-term organ complications
HypercholesterolemiaHigh lipid/cholesterol levels due to genetics or poor dietExcess cholesterol in blood; lipid metabolism imbalanceRisk of atherosclerosis, heart attacks, and strokes
Phenylketonuria (PKU)Deficiency of the phenylalanine hydroxylase enzymeInability to metabolise phenylalanine
Accumulation in blood
Causes intellectual disability, developmental delays, and neurological disorders if untreated


Biomolecules as Therapeutic Targets

Biomolecules play a central role in the process of finding therapeutic approaches. Strategies that aim at particular biomolecules alter diseases; for example, insulin among diabetic patients, statins in minimising cholesterol, and enzyme replacement therapy in cases of PKU. As the fields of biotechnology and pharmacology keep developing, biomolecular aims and objectives remain utilised and implemented in novel therapies and patient’ benefits.

Other Useful Resources:


Recommended Video on Biomolecules

Frequently Asked Questions (FAQs)

1. What are 5 examples of disaccharides?

Common disaccharides include:

  • Sucrose (table sugar)
  • Maltose.
  • Lactose.
  • Trehalose.
  • Lactulose.
2. What are Amino acids?

Amino acids are biomolecules that include both carboxylic acid and amine functional groups. They are carboxylic acid derivatives in which an amino group replaces one hydrogen atom of a carbon atom. Carbon, hydrogen, oxygen, and nitrogen are the primary components of amino acid, while more elements may be added. The structural-functional groups of amino acids are classed as alpha, beta, gamma, or delta, depending on where they are located. Proteins are made up of amino acids, which are the building components.

3. Explain the term nucleic acid.

Nucleic acids are crucial biomolecules found in all living organisms. Because nucleotides have a repeating structure, they are also known as polynucleotides. A phosphate group, sugar, and nitrogenous bases make up nucleic acid. 

Nucleic acid types include:

RNA: The structure of RNA (ribonucleic acid) is a single-stranded helix.

DNA: The double-stranded helix structure of DNA (deoxyribonucleic acid).

4. What is ATP? State its function.

ATP (adenosine triphosphate) is an energy-carrying molecule found in all living creatures' cells. ATP is a molecule that absorbs chemical energy from the breakdown of food molecules and then releases it to power other cellular operations.

5. Define Metabolism.

Metabolism refers to the chemical reactions that occur within the cells of the body to convert food into energy. This energy is required for everything our bodies do, from moving to thinking to developing. The chemical reactions of metabolism are controlled by certain proteins in the body.

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You may download notes for Chapter 8: Cell: The Unit of Life, Chapter 9: Biomolecules, and Chapter 10: Cell Cycle and Cell Division for Class 11 Biology from the below reliable sources:

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Chapter 8: Cell: The Unit of Life

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Chapter 9: Biomolecules

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Chapter 10: Cell Cycle and Cell Division

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