Once activated, the complement cascade is an ordered process. Each reaction leads to another reaction. This activity asks you to place the cascade reactions in the order they occur, starting with the C1.

A. C1 cleaves C2 and C4

B. C2a and combine to form an enzyme

C. C1 interacts with antibody that is bound to pathogen.

D. C3 is split into C3a and C3b

C-A-B-D

Explanation:

The complement system: complement cascade is an ordered process is which every step occur in a orderly fashion; first

1) C1 interacts with an antibody that antibody is bound to a pathogen

and after it

2) C1 cleaves C2 and C4

, after it

3) C2a component and C4b both combine to form an enzyme,

after that

4) C3 is split into i) C3a and ii) C3b component

In complement system one sub-unit is large and other one is small.