Video Transcript
Complement proteins are an
important component of the immune response. What is the primary role of
complement proteins? (A) They bind to healthy cells that
are near to an infected cell and stimulate the production of enzymes to inhibit
virus replication. (B) They destroy pathogens by
lysing their membranes or making them easily recognized and engulfed by
phagocytes. (C) They regulate communication
between different immune cells and between immune cells and other body cells. (D) They recruit cytotoxic T cells
to sites in the body that have a large number of pathogens or foreign particles.
The immune system is composed of
many cells and proteins throughout the body. Complement proteins play an
important role in this system, so let’s briefly go over how they work
Complement is a group of proteins
that circulate in the body, which can target pathogens for destruction. They can do this in a couple of
ways. One way is that the complement
proteins assemble on the surface of a pathogen to form a pore, or a hole, in the
cell membrane of the pathogen. This causes the pathogen to burst
by lysis. Another way is by marking the
pathogen for destruction. Here, other immune cells can
recognize the complement proteins bound to a pathogen and destroy that pathogen by
engulfing it by phagocytosis.
Let’s now go through our answer
choices and choose the best one that describes the primary role of complement
proteins.
Answer choice (A) is incorrect, as
this seems to be describing a specialized cytokine called interferon. Interferon is very useful to stop
viral infections from occurring.
Answer choice (B) seems to be
correct, as it mentions both mechanisms by which complement can ultimately destroy a
pathogen. But before deciding on this as our
final answer, let’s look at the remaining options.
Answer choice (C) is describing how
cytokines work as a communication molecule for immune cells and other body
cells. So this is incorrect.
Answer choice (D) describes a type
of cytokine called a chemokine, which are responsible for recruiting immune cells to
different sites.
Therefore, the option that best
describes the primary role of complement proteins is given by answer choice (B). They destroy pathogens by lysing
their membranes or making them easily recognized and engulfed by phagocytes.
