Final answer:
The statement that C1q/C1r/C1s are all cleaved fragments of C1 protein is false. The C1 complex, part of the immune system's complement system, consists of one molecule of C1q and two molecules each of C1r and C1s, which are not cleaved fragments but individual proteins. The cleavage by C1q affects complement components C2 and C4, producing fragments during activation.
Step-by-step explanation:
C1 complex is part of the complement system, which is a critical component of the immune system. It consists of various proteins that work together to fight infections. Specifically, the C1 complex is involved in the classical pathway of complement activation and is composed of one molecule of C1q and two molecules each of C1r and C1s. C1q binds to an antigen-antibody complex on an invading pathogen, which subsequently activates C1r and C1s. These are not cleaved fragments of C1; instead, they are individual proteins that associate to form the functional C1 complex. The cleavage induced by C1q is on different complement components, namely C2 and C4, which then split into two fragments each during the complement activation process.