申論題

6.An antibody molecule can be divided into two regions. One is called the constant region or C region, and the other one is known as the variable region or V region. The bypervariable sequences in the V region correspond to three loops localized to the surface of the molecule. The loops are termed complementary-determining regions, or CDRs. Please explain: (1) What the "complementary" means, and (2) How important the CDRs function in antigen binding? (5 分)