Question:
Draw the structure of an antibody molecule and label any four of its parts.
Draw the structure of an antibody molecule and label any four of its parts.
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An antibody molecule is represented as $\text{H}_2\text{L}_2$ because it contains exactly 2 heavy chains and 2 light chains bound by disulfide bridges.
Updated On: Aug 16, 2026
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Solution and Explanation
Concept:
An antibody, also termed an immunoglobulin (Ig), is a Y-shaped glycoprotein synthesized by differentiated B-cells (plasma cells) to neutralize foreign antigens.
Structural Details of an Antibody Molecule ($\text{H}_2\text{L}_2$):
• It is composed of four polypeptide chains: two identical heavy (H) chains and two identical light (L) chains.
• These chains are interconnected through covalent disulfide bonds.
• Each chain possesses a Variable (V) region at its amino-terminal tip, which forms the antigen-binding site, and a Constant (C) region that dictates effector function. Labelled Structure Outline: Below is the structural configuration highlighting the four primary component labels: Antigen-Binding Site (Paratope) _/ _/ | V | | V | <-- Variable Region (Light & Heavy) |___| |___| | C | | C | <-- Light Chain (L) |___| |___| \ / \-- Disulfide Bonds --/ (-S-S-) | | | C | <-- Heavy Chain (H) |___| | | | C | <-- Constant Region (Heavy Chain) |___| Key Components for Identification:
• Antigen-binding site (Paratope): Located at the variable tips of both the heavy and light chains.
• Heavy Chain: The longer polypeptide chain.
• Light Chain: The shorter polypeptide chain.
• Disulfide Bonds: Interchain linkages stabilizing the Y-shaped configuration.
• It is composed of four polypeptide chains: two identical heavy (H) chains and two identical light (L) chains.
• These chains are interconnected through covalent disulfide bonds.
• Each chain possesses a Variable (V) region at its amino-terminal tip, which forms the antigen-binding site, and a Constant (C) region that dictates effector function. Labelled Structure Outline: Below is the structural configuration highlighting the four primary component labels: Antigen-Binding Site (Paratope) _/ _/ | V | | V | <-- Variable Region (Light & Heavy) |___| |___| | C | | C | <-- Light Chain (L) |___| |___| \ / \-- Disulfide Bonds --/ (-S-S-) | | | C | <-- Heavy Chain (H) |___| | | | C | <-- Constant Region (Heavy Chain) |___| Key Components for Identification:
• Antigen-binding site (Paratope): Located at the variable tips of both the heavy and light chains.
• Heavy Chain: The longer polypeptide chain.
• Light Chain: The shorter polypeptide chain.
• Disulfide Bonds: Interchain linkages stabilizing the Y-shaped configuration.
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