Biomolecules

Biology
Biomolecules

Biomolecules

Irshad AnwarUpdated on 04 Oct 2025, 03:43 PM IST

Biomolecules are organic compounds essential for life, including carbohydrates, proteins, lipids, and nucleic acids. They form the structural and functional basis of cells and regulate vital processes like metabolism, energy transfer, and heredity. A core NEET and Class 11 Biology topic.

This Story also Contains

What are Biomolecules?
Types of Biomolecules
Functions of Biomolecules
Synthesis and Breakdown of Biomolecules
Role of Biomolecules in Health
Biomolecules NEET MCQs (With Answers & Explanations)
Recommended Video on Biomolecules

Biomolecules

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 – Structure and Functions

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	Sugar Units	Examples	Description
Monosaccharides	1 unit	Glucose	Simple sugar Basic unit of carbohydrates.
Disaccharides	2 units	Sucrose (Glucose + Fructose)	Formed by linking two monosaccharides.
Oligosaccharides	2–10 units	Raffinose	Contains a few monosaccharide units Not as large as polysaccharides.
Polysaccharides	More than 10 units	Starch, 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:

Function	Description
Primary Source of Energy	Provides quick energy through glucose for body and brain functions.
Energy Storage	Excess glucose is stored as glycogen in the liver and muscles for later use.
Sparing Protein Use	Prevents proteins from being used for energy, preserving them for body repair.
Fat Metabolism	Helps in the complete oxidation of fats and prevents ketone body formation.
Structural Role	Forms part of DNA (deoxyribose) and RNA (ribose), essential for the genetic code.

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 – Types and Roles

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

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

Type	Structure/Composition	Examples	Description
Simple Proteins	Made of only amino acids	Albumin, Globulin	Yield only amino acids on hydrolysis no non-protein part.
Conjugated Proteins	Protein + non-protein part	Hemoglobin (protein + heme group)	Contain a prosthetic group like metal ions, lipids, or carbohydrates.
Fibrous Proteins	Long, thread-like structure	Keratin, Collagen	Provide structural support insoluble in water.
Globular Proteins	Spherical, compact structure	Enzymes, Antibodies	Functional proteins Soluble in water and performs metabolic functions.
Derived Proteins	Formed from the breakdown of proteins	Peptones, Proteoses	Products 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:

Function	Description
Structural Support	Proteins like collagen and keratin provide strength and structure to tissues.
Enzymatic Activity	Enzymes (which are proteins) catalyse biochemical reactions in the body.
Transport	Proteins like haemoglobin transport oxygen and others help carry nutrients.
Defense Mechanism	Antibodies (immunoglobulins) are proteins that help fight infections.
Hormonal Regulation	Some 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 – Structure and Classification

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	Structure/Composition	Examples	Description
Simple Lipids	Esters of fatty acids with alcohols	Fats (triglycerides), Oils, Waxes	Composed of glycerol and fatty acids, They serve as energy reserves and insulation.
Compound Lipids	Lipids + additional groups	Phospholipids, Glycolipids	Contain other groups like phosphate or sugar, Major components of cell membranes.
Derived Lipids	Hydrolysis products of simple/compound lipids	Steroids (cholesterol), Fatty acids	Obtained from the breakdown of simple or compound lipids involved in hormone synthesis.
Steroids	Four fused carbon rings	Cholesterol, Testosterone	Function as hormones, vitamins, and cell membrane components.
Waxes	Esters of long-chain fatty acids & alcohols	Bee wax, Lanolin	Provide 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:

Function	Description
Energy Storage	Lipids store energy efficiently, providing 9 kcal/g, more than carbohydrates or proteins.
Structural Component	Phospholipids form the basic structure of cell membranes (lipid bilayer).
Insulation and Protection	Lipids insulate the body and protect vital organs by cushioning them.
Hormone Synthesis	Cholesterol is a precursor for steroid hormones like estrogen and testosterone.
Fat-Soluble Vitamin Absorption	Lipids 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 – DNA, RNA, and Nucleotides

Nucleic acids can be defined as large biomolecules that are made up of a chain of nucleotides. A nucleotide is a molecule that has a sugar, a phosphate group and 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	Structure/Composition	Examples	Description
DNA (Deoxyribonucleic Acid)	Double-stranded polymer of nucleotides	Human DNA	Stores genetic information composed of deoxyribose sugar, phosphate, and bases.
RNA (Ribonucleic Acid)	Single-stranded polymer of nucleotides	mRNA, tRNA, rRNA	Involved in protein synthesis contains ribose sugar instead of deoxyribose.
Nucleotides	Nitrogenous base + pentose sugar + phosphate	ATP (adenosine triphosphate)	Building blocks of nucleic acids ATP stores and transfers energy in cells.
Nucleosides	Nitrogenous base + pentose sugar	Adenosine, Cytidine	Precursors of nucleotides, lacking a phosphate group.
Other Nucleotide Derivatives	Modified nucleotides involved in signalling	cAMP (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:

Function	Description
Genetic Information Storage	DNA stores the hereditary genetic code that controls cell function and inheritance.
Protein Synthesis	RNA helps translate genetic information into proteins via mRNA, tRNA, and rRNA.
Energy Transfer	ATP, a nucleotide, stores and transfers energy within cells for metabolic processes.
Cell Signaling	Molecules like cAMP act as secondary messengers in cellular communication.
Regulation of Metabolism	Nucleotides 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:

Type	Structure/Composition	Examples	Description
Fat-Soluble Vitamins	Organic compounds soluble in fats	Vitamins A, D, E, and K	Stored in body fat, involved in vision, bone health, antioxidant functions, and blood clotting.
Water-Soluble Vitamins	Organic compounds soluble in water	Vitamin B-complex, Vitamin C	Not stored in large amounts They act mainly as coenzymes in metabolism and antioxidant roles.
Coenzymes	Non-protein organic molecules derived from vitamins	NAD⁺ (from Niacin), FAD (from Riboflavin)	Helps enzymes in catalysing biochemical reactions by transferring chemical groups.
Provitamins	Precursors are converted into active vitamins	Beta-carotene (Vitamin A precursor)	Converted by the body into active vitamins as needed.
Mineral-based Coenzymes	Inorganic ions that help enzyme function	Zinc, 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:

Function	Description
Enzyme Activation	Coenzymes derived from vitamins help enzymes catalyse metabolic reactions efficiently.
Antioxidant Protection	Vitamins like C and E neutralise free radicals, protecting cells from oxidative damage.
Bone and Vision Health	Vitamin D aids calcium absorption for bones. Vitamin A is essential for vision and eye health.
Immune Function Support	Vitamins like C and A boost immune responses and help fight infections.
Blood Clotting and Healing	Vitamin 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

The synthesis and breakdown of biomolecules includes following pathways:

Anabolic Pathways

In anabolism, small and simpler molecules are converted into large and complex molecules, requiring energy input.

Examples include amino acids form keratin, glucose molecules forms glycogen and starch

Catabolic Pathways

In catabolism, large complex molecules are degraded into smaller simpler molecules.

Examples include protein is broken down into amino acids, lipids are broken into fatty acids

These two pathways are essential for total metabolism in an organism. The difference between the two is given in the table below:

Aspect	Anabolic Pathways	Catabolic Pathways
Definition	Biosynthetic processes that build larger molecules from smaller ones.	Degradative processes that break down large molecules into simpler ones.
Energy Requirement	Requires energy input (endergonic).	Releases energy (exergonic).
Molecules Involved	Builds macromolecules like proteins, nucleic acids, and polysaccharides.	Breaks down macromolecules like carbohydrates, fats, and proteins.
Purpose	Supports growth, repair, and storage.	Provides energy (ATP) for cellular activities.
Example	Synthesis of proteins from amino acids.	Breakdown of glucose in cellular respiration to produce ATP.

Enzymatic Reactions

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.

Metabolic Pathways Examples

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

Process	Type	Key Steps	End Products	Function
Glycolysis	Catabolic	Breakdown of glucose into pyruvate in the cytoplasm	2 Pyruvate, 2 ATP, 2 NADH	The initial stage of cellular respiration provides energy and metabolic intermediates.
Krebs Cycle	Catabolic	Oxidation of pyruvate-derived acetyl-CoA in mitochondria	ATP, NADH, FADH₂, CO₂	Generates energy carriers (NADH, FADH₂) for the electron transport chain.
Protein Synthesis	Anabolic	Transcription (DNA → mRNA) and translation (mRNA → protein)	Functional proteins (polypeptides)	Builds proteins necessary for structure, enzymes, and cell function.

Role of Biomolecules in Health

Biomolecules play an important role in maintaining human health:

Importance in Metabolism and Homeostasis

Biomolecules are involved 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:

Disorder	Cause	Effect on Metabolism	Health Impact
Diabetes	Lack 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
Hypercholesterolemia	High lipid/cholesterol levels due to genetics or poor diet	Excess cholesterol in blood; lipid metabolism imbalance	Risk of atherosclerosis, heart attacks, and strokes
Phenylketonuria (PKU)	Deficiency of the phenylalanine hydroxylase enzyme	Inability 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.

Biomolecules NEET MCQs (With Answers & Explanations)

Important topics in the chapter Biomolecules are the

Types of Biomolecules (Proteins, Carbohydrates, Lipids, Nucleic Acids)
Functions of Biomolecules
Biomolecules in Health and Diseases
Enzymes

Practice Questions for NEET

Q1. The cellular pool comprises hundreds of organic and inorganic biomolecules. The organic molecules include

Carbohydrates
Proteins
Nucleic acids
More than one option correct

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Correct answer: 4) More than one option correct

Explanation:

The organic molecules present within the cell are categorized into:

1. Carbohydrates:
- Monosaccharides (e.g., glucose) are simple sugars serving as energy sources.
- Polysaccharides (e.g., starch, glycogen) are complex carbohydrates providing both energy and structural support to cells.

2. Proteins:
- Composed of amino acids, proteins are fundamental to various cellular activities such as enzyme function, structural integrity, signal transmission, and material transport.

3. Lipids:
- This group encompasses fats, phospholipids, and steroids which are crucial for energy storage, maintaining cell membrane structure, and participating in signaling pathways.

4. Nucleic Acids:
- DNA and RNA are the genetic material, essential for storing, transferring, and synthesizing proteins according to genetic instructions.

Hence, the correct answer is option 4) More than one option is correct.

Q2. Organic molecules contain

Nitrogen
Sulphur
Oxygen
Zinc

Correct answer: 3) Oxygen

Explanation:

Biomolecules are organic compounds essential to life, composed primarily of carbon (C), hydrogen (H), and oxygen (O). These molecules form the structural and functional basis of living organisms. In addition to these elements, some biomolecules may also contain nitrogen (N), phosphorus (P), sulfur (S), and other trace elements.

Hence, the correct answer is option 3) Oxygen.

Q3. Lecithin, a small molecular weight organic compound found in living tissues, is an example of:

Amino acids
Phospholipids
Glycerides
Carbohydrates

Correct answer: 2) Phospholipids

Explanation:

Some lipids have phosphorus and a phosphorylated organic compound in them. These are phospholipids. They are found in cell membranes. Lecithin is one example.

Option (3) is incorrect, as glycerides are another group of lipids in which both glycerol and fatty acids are present.

Option (1) and (4) are incorrect as amino acids and carbohydrates are separate groups of biomolecules.

Hence, The correct answer is option 2) Phospholipids.

Also Read:

Biomolecules

What are Biomolecules?

Types of Biomolecules

Carbohydrates – Structure and Functions

Proteins – Types and Roles

Lipids – Structure and Classification

Nucleic Acids – DNA, RNA, and Nucleotides

Vitamins and Coenzymes

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