An antibody molecule
A) will either consist of a constant region or a variable region.
B) forms an X-shaped protein molecule.
C) contains an antigen-binding site on each arm.
D) contains four light chains and two heavy chains.
E) contains constant regions that bind to the antigen.

Question

Quizplus · Accepted Answer

An antibody molecule contains an antigen-binding site on each arm, allowing it to bind to specific target antigens. The other answer options are incorrect: 
A) An antibody molecule consists of both constant and variable regions. 
B) An antibody molecule may form an X-shape, but this is not a defining characteristic. 
D) An antibody molecule contains two light chains and two heavy chains. 
E) The constant regions of an antibody molecule may play a role in binding to antigens or other molecules, but they do not bind directly to the antigen.

An Antibody Molecule