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.
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
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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.
Biomolecules are needed by the body to perform different life processes. The various types of biomolecules are listed below:
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.
Different types of carbohydrates are discussed below:
Type of Carbohydrate | No. of Sugar Units | Example(s) | Description |
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Monosaccharides | 1 unit | Glucose |
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Disaccharides | 2 units | Sucrose (Glucose + Fructose) |
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Oligosaccharides | 2–10 units | Raffinose |
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Polysaccharides | More than 10 units | Starch, Cellulose |
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Some of the major functions of carbohydrates are discussed below in the table:
Function | Description |
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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. |
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 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.
Some major types of protein and their structure and composition are discussed below:
Type of Protein | Structure/Composition | Example(s) | Description |
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Simple Proteins | Made of only amino acids | Albumin, Globulin |
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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 |
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Globular Proteins | Spherical, compact structure | Enzymes, Antibodies |
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Derived Proteins | Formed from the breakdown of proteins | Peptones, Proteoses | Products of partial hydrolysis of simple or conjugated proteins. |
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 |
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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 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. |
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 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.
Triglycerides act as energy storage or fat, phospholipids are part of cell membranes, and steroids include cholesterol, which is a hormone.
Type of Lipid | Structure/Composition | Example(s) | Description |
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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. |
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 |
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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. |
Usual lipids are the fats and oils (triglycerides), phospholipids that set up cell membranes, and sterol–cholesterol.
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.
Major types of nucleic acids are discussed below in the table:
Type of Nucleic Acid | Structure/Composition | Example(s) | Description |
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DNA (Deoxyribonucleic Acid) | Double-stranded polymer of nucleotides | Human DNA |
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RNA (Ribonucleic Acid) | Single-stranded polymer of nucleotides | mRNA, tRNA, rRNA |
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Nucleotides | Nitrogenous base + pentose sugar + phosphate | ATP (adenosine triphosphate) |
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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. |
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 |
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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. |
DNA and RNA, where DNA is the carrier of the code and RNA takes part in the code implementation.
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.
Some of the major types of vitamins and coenzymes are discussed below:
Type | Structure/Composition | Example(s) | Description |
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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 |
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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 |
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Some of the major functions of vitamins and coenzymes are discussed below in the table:
Function | Description |
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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: 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).
Some important functions of Biomolecules are discussed below:
Function | Explanation |
Energy Storage |
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Structural Support |
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Catalysis |
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Genetic Information |
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Cell Communication |
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Regulation and Coordination of Biological Processes |
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There are two pathways for a breakdown of Biomolecules. Both of process of synthesis and breakdown of biomolecules is discussed below:
Aspect | Anabolic Pathways | Catabolic Pathways |
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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. |
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.
Major example of Metabolic Pathways are discussed below in the table:
Process | Type | Key Steps | End Products | Function |
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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. |
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.
Some common disorders related to biomolecule metabolism are:
Disorder | Cause | Effect on Metabolism | Health Impact |
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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 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:
Beriberi | |
Difference between Prokaryotic and Eukaryotic Cells | |
Biological Functions of Proteins | Types of Cells in the Human Body |
Common disaccharides include:
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.
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).
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.
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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