Let’s explore antibodies a little more. Chapter 16 of the textbook covers Antibodies with the figure below. Which of the following are true of antibodies?

A protein with quaternary structure having 2 longer “heavy chains” and 2 “light chains”.
A protein secreted by B lymphocytes into body fluids with binding sites for 2 antigens.
Proteins recognized very specifically and bound by white blood cells called lymphocytes.
All of the above