Biology Immunity MDCAT 2014
PMDC Verified Question 95 of 99
Which part of antibody recognizes the antigen during immune response?
A
Heavy part
B
Constant part
C
Light part
D
Variable part
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Variable part
Concept:

Antibodies (immunoglobulins) have a highly specific lock-and-key mechanism to bind to countless diverse antigens.

Formula:

None

Solution:

  • An antibody is a Y-shaped molecule. The tips of the "Y" form the antigen-binding site.


  • This specific region is composed of the variable parts (variable regions) of both the heavy and light chains.


  • Its unique amino acid sequence allows it to recognize and bind tightly to one specific antigen epitope.


Why other options are incorrect:

  • Constant part: Determines the mechanism of action/class of the antibody (e.g., IgG, IgE), but plays no role in specific antigen recognition.

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