Complement proteins

Question 1

is a collection of at least 20 soluble proteins that are synthesized in the liver and released into
the blood in their inactive forms.

Answer 1

The complement system

Question 2

The complement system They only become activated once they encounter and attach to specific receptors on body cells in a process known as

Answer 2

complement fixation

Question 3

The complement system

Many of them upon activation become ___ enzymes that degrade other complement proteins thus forming an
enzymatic cascade capable of tremendous amplification.

Answer 3

Many of them upon activation become protolytic enzymes that degrade other complement proteins thus forming an
enzymatic cascade capable of tremendous amplification.

Question 4

Triggered upon the exposure of a complement protein known as C3 to microbial surface molecules in the
absence of antibody.

Answer 4

Spontaneous binding

Question 5

Spontaneous binding Result of spotaneous Activation

Answer 5

C3 –> C3b and Bf–> Bb (Factor b- activated b)

Alternative Pathway

Question 6

Antibody-binding

Answer 6

Classical Pathway

Question 7

Triggered by the fixation of C1 complex to antibody (IgM or IgG) that has combined with an antigen which in
turn will prompt the cleavage of
C4 –> C4b and C2 –>C2a

Answer 7

Classical Pathway

Question 8

Mannose-binding

Answer 8

Lectin Pathway

Question 9

Plasma mannose-binding lectin will bind to oligosaccharides on certain microbes in order to activate the MBL
complex that in turn will directly activate c1 to break down C4–> C4b and C2 –> C2a

Answer 9

Lectin Pathway

Question 10

The 3 activation pathways will converge to a common pathway which is the activation of the C3 convertase that will cleave __

Answer 10

C3 –> C3a and C3b

Question 11

3 main functions of Complement System

Answer 11

Opsonization and phagocytosis
Inflammation
- Anaphylaxis & leukocyte chemotaxis
Cell lysis

Question 12

C5a, and to a lesser extent C4a and C3a promotes inflammation via

Answer 12

Anaphylaxis & leukocyte chemotaxis

Question 13

C5a, and to a lesser extent C4a and C3a will release

Answer 13

Histamine from mast cells

Question 14

Histamine from mast cells are also called

Answer 14

anaphylotoxins

Question 15

C5a activates the lipoxygenase pathway of arachidonic acid metabolism in neutrophils and monocytes causing
the release of more inflammatory mediators specifically

Answer 15

the leukotrienes.

Question 16

− C5b6789 means

Answer 16

C5b will now combine with complements C6, 7, 8, and 9 to form the cylindrical membrane attack complex (MAC)

Question 17

cylindrical membrane attack complex (MAC)

Answer 17

whose sequential deposition on cells will essentially drill holes into the cell membrane making the cell permeable
to H2O and ions = cell it will swell until it burst in the process of cell lysis

Question 18

Complement proteins are regulated by:

Answer 18

C1 Inhibitor
Decay accelerating factor (DAF)
CD59 inhibits formation of MAC
Other circulating regulatory proteins

Question 19

prevents formation of C3 convertase thus stopping all pathways of the complement system. This is a complement Protein

Answer 19

Decay accelerating factor (DAF)