The Complement System: Classical, Lectin, and Alternative Pathways

Which of the following is NOT considered a feature of the innate immune system, as introduced in the video?

• Barrier Surfaces

• Complement System

• Inflammatory Response

• Adaptive Immunity

In the 17th century, what observation was made about blood from lab animals regarding bacteria?

• It contained antibodies that killed bacteria.

• It had bacterial killing properties in vitro, but these were lost when heated.

• It could only kill bacteria if the animals had been previously infected.

• It had no effect on bacterial growth.

Jules Bordet's experiments in the 1890s identified two distinct protective components in the blood. What were they?

• Antibodies and antigens

• Heat-stable and heat-labile components

• Phagocytes and lymphocytes

• Red blood cells and white blood cells

Who named the heat-labile component of the blood 'complement' and why?

• Jules Bordet, because it completed the immune response.

• Paul Ehrlich, because it complemented the heat-stable aspect of the immune system.

• Louis Pasteur, because it supplemented the body's natural defenses.

• Robert Koch, because it was a complex system of proteins.

The mammalian complement system is primarily composed of what type of molecules that circulate in the blood?

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Many proteins in the mammalian complement system are zymogens. What does this mean?

• They are always active and ready to fight pathogens.

• They are enzymes that are inactive until a biochemical change activates them.

• They are structural proteins that form barriers against infection.

• They are signaling molecules that communicate between immune cells.

In complement system nomenclature, what does the lowercase 'a' fragment typically represent after a protein is cleaved?

• The larger binding portion

• The active enzyme

• The smaller anaphylatoxin fragment

• The inactive precursor

Which complement protein is an exception to the rule that the 'a' fragment is smaller and the 'b' fragment is larger?

• C1

• C2

• C3

• C4

When naming a protein complex in the complement system, how are its fragments typically listed?

• Alphabetically

• In the order of their discovery

• In the order in which they bind

• From largest to smallest

Which of the following is NOT one of the three distinct pathways through which complement can be activated?

• Classical Pathway

• Lectin Pathway

• Adaptive Pathway

• Alternative Pathway