Biomolecules Biology Chapter 6

Biomolecules are the essential chemical compounds that make up living organisms. These include macromolecules like carbohydrates, proteins, lipids, and nucleic acids, and micromolecules like water, minerals, and vitamins. The study of these chemical compounds is known as biochemistry.

The body of any living organism functions through a combination of biological and chemical processes. All of these involve various biomolecules working together to sustain life.

🍬 1. Carbohydrates

Carbohydrates are organic compounds made up of carbon (C), hydrogen (H), and oxygen (O), generally in a 1:2:1 ratio. They are also called saccharides.

🧪 Types of Carbohydrates:

1. Monosaccharides: Simple sugars like glucose, fructose, galactose.
2. Disaccharides: Made up of two monosaccharides. Example: Sucrose = glucose + fructose.
3. Polysaccharides: Long chains of monosaccharides. Examples:

• Starch: Energy storage in plants.
• Glycogen: Energy storage in animals.
• Cellulose: Structural carbohydrate in plant cell walls.

🔍 Functions:

• Provide instant energy
• Structural material (e.g., cellulose)
• Serve as dietary fiber

🧬 2. Proteins

Proteins are large, complex molecules composed of amino acids, linked by peptide bonds. There are 20 naturally occurring amino acids, which combine in various ways to form different proteins.

🔗 Structural Levels of Proteins:

1. Primary structure: Sequence of amino acids.
2. Secondary structure: Alpha-helix or beta-pleated sheets.
3. Tertiary structure: 3D folding.
4. Quaternary structure: Two or more polypeptide chains.

🧪 Functions:

• Enzymatic: Act as catalysts (e.g., amylase)
• Structural: Keratin (hair, nails), collagen (connective tissue)
• Transport: Hemoglobin
• Hormonal: Insulin
• Immune defense: Antibodies

🧴 3. Lipids

Lipids are non-polar organic molecules composed of carbon, hydrogen, and oxygen. They are hydrophobic (water-insoluble).

🧪 Types of Lipids:

1. Simple lipids: Fats and oils (triglycerides).
2. Compound lipids: Phospholipids and glycolipids.
3. Derived lipids: Steroids (cholesterol), vitamins (A, D, E, K).

🔍 Functions:

• Long-term energy storage
• Make up the cell membrane (phospholipid bilayer)
• Insulation and protection
• Precursors of hormones and vitamins

📚 4. Nucleic Acids

Nucleic acids are macromolecules made of nucleotides. Each nucleotide consists of:

• A nitrogenous base (A, T/U, G, C)
• A five-carbon sugar (ribose or deoxyribose)
• A phosphate group

🧪 Types of Nucleic Acids:

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

DNA is double-stranded, while RNA is single-stranded. DNA uses thymine (T), whereas RNA uses uracil (U).

⚙️ 5. Enzymes

Enzymes are biological catalysts, usually proteins, that accelerate chemical reactions in the body.

💡 Properties:

• Speed up reactions without being consumed
• Specific to substrates
• Work best at optimal pH and temperature

🔍 Examples:

• Amylase: Converts starch to sugar
• Lipase: Breaks down fats
• Protease: Digests proteins

🛑 Inhibition:

• Competitive: Inhibitor competes with the substrate.
• Non-competitive: Inhibitor binds elsewhere, changing enzyme shape.

🔁 6. Metabolism

Metabolism is the sum of all chemical reactions occurring in an organism. It includes:

• Catabolism: Breakdown of molecules to release energy.
• Anabolism: Synthesis of complex molecules from simpler ones using energy.

Together, these maintain the metabolic pool – a balance of substances needed for life.

💊 7. Vitamins

Vitamins are organic compounds required in small amounts. They assist enzymes in biological reactions.

🧪 Types:

• Fat-soluble: A, D, E, K – stored in the liver.
• Water-soluble: B-complex, C – not stored, excess excreted.

🔍 Functions:

• Vitamin A: Vision
• Vitamin D: Bone health
• Vitamin E: Antioxidant
• Vitamin K: Blood clotting
• Vitamin C: Wound healing, antioxidant
• Vitamin B: Metabolic coenzymes

🌱 8. Secondary Metabolites

These are organic compounds not essential for basic metabolic functions but help in ecological interactions and defense.

🧪 Examples:

• Alkaloids: Morphine, quinine – medicinal uses
• Flavonoids: Pigments in flowers, fruits
• Terpenoids: Essential oils
• Tannins: Defensive compounds in plants
• Resins: Sticky substances used for protection

Understanding biomolecules is fundamental to understanding life itself. Every structure and process in a living organism relies on these molecules—from the DNA in our cells to the proteins in our muscles, the sugars in our blood, and the lipids in our membranes.