🧬 Introduction and Importance of Biomolecules

All living organisms, from the simplest bacteria to complex humans, are composed of chemical substances known as biomolecules. These molecules form the structural framework, perform vital functions, and regulate biochemical activities of cells.

Biomolecules are the molecular basis of life. Without them, life processes such as metabolism, growth, reproduction, and inheritance cannot occur.

🔹 1️⃣ What Are Biomolecules?

Biomolecules are organic compounds synthesized by living organisms that take part in cell structure, metabolism, and regulation.

They mainly contain the elements:

C – Carbon
H – Hydrogen
O – Oxygen
N – Nitrogen
P – Phosphorus
S – Sulfur
(Collectively remembered as CHONPS)

🔑 Key Memory Line:

Life is carbon-based because carbon forms stable and diverse biomolecules.

🔹 2️⃣ Types of Biomolecules

Biomolecules are broadly classified into two categories:

🧪 (A) Inorganic Biomolecules

Water
Minerals and salts
Gases (O₂, CO₂)

➡️ These are essential for osmotic balance, enzyme activity, and metabolism, but are not synthesized as complex carbon compounds.

🧬 (B) Organic Biomolecules

These are carbon-containing molecules synthesized by living cells:

Carbohydrates – Primary source of energy (e.g., glucose, starch)
Proteins – Structural and functional molecules (e.g., enzymes, antibodies)
Lipids – Energy storage and membrane components (e.g., fats, phospholipids)
Nucleic Acids – Genetic material (DNA and RNA)

🔑 Exam Line:

Organic biomolecules always contain carbon and hydrogen bonds.

🔹 3️⃣ Importance of Biomolecules

Biological Role	Biomolecule Involved	Example
Structural support	Proteins, lipids	Cytoskeleton, cell membrane
Energy source	Carbohydrates, lipids	Glucose, fats
Catalysis	Proteins (enzymes)	Amylase, pepsin
Genetic control	Nucleic acids	DNA, RNA
Regulation & signalling	Proteins, lipids	Hormones, receptors

🔑 One-Line Summary:

Biomolecules control structure, energy, reactions, and inheritance.

🔹 4️⃣ Elements of Life

Although 92 elements occur naturally, only 30–40 are found in living organisms. Among these, six elements dominate.

🌟 Major Elements (Macroelements)

C, H, O, N, P, S
Also: Ca, Mg, K, Na, Cl

🔍 Trace Elements (Microelements)

Fe, Cu, Zn, Mn, Co, Mo, B, Si

➡️ Trace elements usually act as enzyme cofactors.

🔑 NEET Tip:

Deficiency of trace elements affects enzyme function.

🔹 5️⃣ Chemical Composition of a Cell

An average living cell contains:

Water: ~70%
Proteins: ~15%
Lipids: ~3%
Carbohydrates: ~2%
Nucleic acids: ~1%

➡️ Both living and non-living matter are made of the same elements, but life exists due to specific molecular organization and interactions.

🔑 Concept Line:

Life is a property of organized molecules, not just elements.

🔹 6️⃣ Biological Significance of Biomolecules

Drive metabolic pathways
Enable energy production and storage
Control gene expression and inheritance
Maintain cellular structure and communication

🧠 NEET Insight:

Biomolecules form the foundation for chapters on enzymes, metabolism, and molecular genetics.

💡 Questions and Answers

Q1. What are biomolecules?

A1.

Biomolecules are organic compounds made by living organisms that help in building the cell, supplying energy, and controlling life processes.

🔑 Key Points:

Synthesized by living cells
Organic in nature
Perform structural and functional roles

Q2. Name the four major classes of organic biomolecules.

A2.

The four major organic biomolecules are carbohydrates, proteins, lipids, and nucleic acids.

🔑 Key Points:

Carbohydrates → energy
Proteins → structure & enzymes
Lipids → storage & membranes
Nucleic acids → genetic material

Q3. What does CHONPS stand for? Why is it important?

A3.
CHONPS stands for carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. These elements form the backbone of all biomolecules.

🔑 Key Points:

Major elements of life
Essential for biomolecule structure

Q4. Why is water considered an important inorganic biomolecule?

A4.
Water acts as a universal solvent and provides the medium for all biochemical reactions in the cell.

🔑 Key Points:

~70% of cell mass
Medium for metabolism

Q5. Distinguish between organic and inorganic biomolecules.

A5.
Organic biomolecules contain carbon-hydrogen bonds and are synthesized by living cells, while inorganic biomolecules lack such bonds and include water and minerals.

🔑 Key Points:

Organic → carbon-based
Inorganic → simple molecules

Q6. Name two trace elements and state their role.

A6.
Zinc and copper are trace elements that act as cofactors for enzymes and help in metabolic reactions.

🔑 Key Points:

Required in small amounts
Essential for enzyme activity