Why are proteins called the building blocks of life?

Proteins form the structural framework of cells and tissues and perform essential functions such as catalysis, transport, regulation, and defense.

Proteins – The Building Blocks of Life

Q: What happens during protein denaturation?

During denaturation, proteins lose their native structure due to heat, pH change, or chemicals, resulting in loss of biological activity.

Proteins are complex biomolecules composed of amino acids. They are often called the “workhorses of the cell” because they perform a vast range of biological functions essential for life.

What are Proteins?
Structure of Proteins
Types of Proteins
Functions of Proteins
Protein Denaturation
Dietary Sources of Proteins
Practice Questions
FAQs
Summary

What are Proteins?

Protein are high molecular weight nitrogen-containing biomolecules made up of amino acids linked together by peptide bonds. They play crucial roles in growth, repair, metabolism, immunity, and regulation of cellular activities.

Structure of Proteins

Protein are polymers of 20 different amino acids. Their structure is organized into four hierarchical levels:

1. Primary Structure

Linear sequence of amino acids joined by peptide bonds.

2. Secondary Structure

Regular folding into α-helix and β-pleated sheet stabilized by hydrogen bonds.

3. Tertiary Structure

Overall three-dimensional folding due to interactions between R-groups (disulfide bonds, ionic interactions).

4. Quaternary Structure

Association of two or more polypeptide chains (e.g., hemoglobin).

Types

Structural Protein: Collagen, Keratin (hair, skin, nails)
Transport Protein: Hemoglobin (oxygen transport)
Enzymes: Amylase, Pepsin (biological catalysts)
Defensive Protein: Antibodies
Signaling Protein: Insulin, growth hormones
Storage Protein: Ferritin (iron storage)

Functions

Catalyze biochemical reactions (enzymes)
Provide mechanical and structural support
Act as chemical messengers (hormones)
Defend the body against pathogens
Regulate metabolism and gene expression
Transport molecules across membranes and blood

Protein Denaturation

Denaturation is the loss of native protein structure due to heat, extreme pH, or chemicals. This results in loss of biological function.

Example: Cooking an egg causes denaturation of albumin.

Dietary Sources

Animal Sources

Eggs
Meat
Fish
Dairy products

Plant Sources

Legumes
Nuts
Soybean
Quinoa

Protein are essential for growth, muscle repair, enzyme synthesis, and immunity.

Practice Questions

Multiple Choice Questions

Q1. Protein are made up of:

a) Nucleotides b) Amino acids c) Fatty acids d) Sugars

Answer: b) Amino acids

Q2. The bond linking amino acids is:

Answer: Peptide bond

True / False

All protein have the same amino acid sequence – ❌ False
Denaturation destroys protein function – ✅ True

Fill in the Blanks

Protein are polymers of Amino acids
3D folding of protein is called Tertiary structure

FAQs

Why are protein important?
They are essential for growth, repair, enzymatic reactions, hormones, and immune defense.

What happens during protein denaturation?
The protein loses its native shape and biological activity.

Carbohydrates

Wikipedia – Protein Structure .

Summary

Proteins are indispensable biomolecules responsible for nearly every cellular function. Their specific structure determines their function, making them central to life processes such as metabolism, immunity, movement, and regulation.

Proteins aren’t just nutrients — they are molecular machines that keep life running.

Proteins