Biomolecules - types, structure, and functions helpful for class 11th and neet Biology preparation

"Biomolecules are the basic building blocks of life. In Class 11 Biology (Chapter 9), biomolecules like carbohydrates, proteins, and nucleic acids are studied in detail..."

Biomolecules: The Chemical Basis of Life

Biomolecules are the organic compounds essential for life. They form the structural and functional basis of all living organisms. Everything from your hair to your hormones is made up of biomolecules.

Biomolecules - types, structure, and functions helpful for class 11th and neet Biology preparation

What are Biomolecules?

Biomolecules are carbon-based compounds naturally occurring in living organisms. They play roles in structure, metabolism, energy storage, and genetic information transfer.

The four most important elements in biomolecules are:

Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)

(Also Phosphorus (P) and Sulfur (S) in some molecules)

Types of Biomolecules: The Building Blocks of Life

Have you ever wondered what makes up the cells in your body? How do we get energy from food? What gives structure to our skin, hair, or muscles? The answer lies in biomolecules – the essential compounds that power and sustain life.

Biomolecules are naturally occurring organic compounds found in all living organisms. They are made mainly of four key elements: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) – commonly remembered as CHON. Some also include elements like phosphorus (P) and sulfur (S). These tiny molecules play huge roles in growth, energy production, repair, and more.

Let’s break down the four major types of biomolecules and understand what each one does:

1. Carbohydrates – The Instant Energy Source

Carbohydrates are often called sugars or saccharides. They are the primary energy source for the body, especially for the brain and muscles. These biomolecules are made up of carbon, hydrogen, and oxygen, usually in a 1:2:1 ratio.

Examples:

Glucose (found in blood)
Sucrose (table sugar)
Starch (stored in plants)
Glycogen (stored in animals)

2. Proteins – The Body’s Workers

Proteins are made up of smaller units called amino acids, joined in chains. They perform a variety of functions – from building tissues and muscles to acting as enzymes and hormones. Proteins also help in immunity, transport, and cell communication.

Examples:

Enzymes (like amylase)
Hemoglobin (carries oxygen in blood)
Insulin (regulates sugar levels)
Keratin (found in hair and nails)

Did you know? Your body needs 20 different amino acids to make all the proteins it requires!

3. Lipids – The Energy Reserves

Lipids are commonly known as fats and oils. Unlike carbs, they provide long-term energy storage. They also make up cell membranes and help in the absorption of vitamins. Lipids are composed of fatty acids and glycerol.

Examples:

Triglycerides (fats)
Phospholipids (form cell membranes)
Cholesterol (helps make hormones)

4. Nucleic Acids – The Information Keepers

Nucleic acids are the blueprints of life. They carry genetic instructions that guide cell function and heredity. These biomolecules are made of nucleotides, which include a sugar, phosphate group, and nitrogenous base.

Two main types:

DNA (Deoxyribonucleic Acid): Stores genetic information.
RNA (Ribonucleic Acid): Helps in protein synthesis.

Enzymes –

Enzymes are biological catalysts that speed up the chemical reactions in living organisms. They are usually proteins, although some RNA molecules can also act as enzymes (ribozymes). Enzymes are essential for life, as they facilitate nearly all biological processes, including digestion, metabolism, and DNA replication.

Characteristics of Enzymes:

1. Specificity:

Enzymes are highly specific in terms of the reactions they catalyze. They work on a specific substrate (the molecule they act upon) to convert it into a product. This specificity is often compared to a lock and key model, where the enzyme is the "lock" and the substrate is the "key."

2. Activation Energy Reduction:

Enzymes lower the activation energy required for a reaction to occur. By doing this, they make reactions happen more efficiently and at lower temperatures, which is crucial for maintaining life in organisms that are sensitive to temperature changes.

3. Reusability:

Enzymes are not consumed in the reaction. They are reused multiple times to catalyze the same reaction.

How Enzymes Work:

1. Active Site:

The region of the enzyme where the substrate binds is called the active site. The enzyme has a unique three-dimensional shape that allows only specific substrates to bind.

2. Enzyme-Substrate Complex:

When the substrate binds to the enzyme's active site, it forms an enzyme-substrate complex. This complex stabilizes the transition state, lowering the energy required for the reaction.

3. Catalysis:

The enzyme facilitates the chemical reaction, causing the substrate to be converted into product(s). After the reaction, the enzyme releases the product(s) and is free to catalyze the next reaction.

Factors Affecting Enzyme Activity:

1. Temperature:

Each enzyme has an optimum temperature at which it works best. High temperatures can denature (damage) the enzyme, causing it to lose its shape and function.

2. pH:

Enzymes also have an optimum pH. Extreme pH levels can alter the enzyme's structure, affecting its ability to bind with the substrate.

3. Substrate Concentration:

As the concentration of the substrate increases, the rate of reaction increases until the enzyme becomes saturated with substrate. At this point, the reaction rate levels off.

4. Enzyme Concentration:

Higher enzyme concentration can lead to faster reactions, provided there is enough substrate to bind with.

Enzyme Inhibition:

1. Competitive Inhibition:

Inhibitors compete with the substrate for the enzyme's active site. The inhibitor binds to the active site, preventing the substrate from binding.

2. Non-Competitive Inhibition:

Inhibitors bind to a different part of the enzyme (not the active site), changing the enzyme's shape and thus reducing its ability to bind with the substrate.

3. Allosteric Regulation:

Some enzymes are regulated by molecules that bind to an allosteric site (a site different from the active site). These molecules can either activate or inhibit the enzyme's activity.

Types of Enzymes:

1. Oxidoreductases:

Catalyze oxidation-reduction reactions (e.g., dehydrogenase).

2. Transferases:

Transfer functional groups (e.g., aminotransferases).

3. Hydrolases:

Catalyze hydrolysis (e.g., lipases, proteases).

4. Lyases:

Remove groups without hydrolysis (e.g., decarboxylases).

5. Isomerases:

Catalyze isomerization (e.g., glucose-6-phosphate isomerase).

6. Ligases:

Join two molecules (e.g., DNA ligase)

Important Terms:

Substrate: The molecule upon which an enzyme acts.
Product: The outcome of the enzymatic reaction.
Active Site: The region of the enzyme where the substrate binds.
Catalysis: The process of speeding up a chemical reaction.
Enzyme-Substrate Complex: The intermediate formed when an enzyme binds with its substrate.