The video explains the classical and lectin pathways of complement activation, emphasizing the role of antibodies in the classical pathway and the use of mannose-binding lectin (MBL) in the lectin pathway. MBL binds to sugars on pathogen surfaces, activating MASP, which then splits C4 and C2, leading to the formation of C3 and C5 convertases. This process ultimately results in the formation of the membrane attack complex (MAC), which disrupts the pathogen's membrane. The video also highlights the similarities and differences between the classical and lectin pathways, with a brief mention of the alternative pathway to be covered in a subsequent video.

What is required for the activation of the classical pathway of complement?

• Proteins

• Sugars

• Antibodies

• Lipids

Which component is crucial for the lectin pathway of complement activation?

• C1 protein

• Mannose-binding lectin (MBL)

• Antibodies

• Lipids

What does MBL bind to on the pathogen surface?

• Sugars

• Nucleic acids

• Lipids

• Proteins

What is the role of MASP in the lectin pathway?

• It acts as a serine protease

• It binds to antibodies

• It forms a pore in the membrane

• It deactivates C4

Which proteins are involved in forming the C3 convertase?

• C4B and C2A

• C1 and C2

• MBL and MASP

• C5 and C6

What is the function of the membrane attack complex (MAC)?

• To form a pore in the pathogen membrane

• To split C3

• To bind antibodies

• To activate C1

How does the lectin pathway differ from the classical pathway?

• It does not form a MAC

• It does not involve C4

• It uses sugars instead of antibodies

• It uses antibodies instead of sugars

What is the initial step in the lectin pathway?

• Activation of C5

• Activation of C1

• Formation of MAC

• Binding of MBL to sugars

Which pathway will be discussed in more detail in the next video?

• Classical pathway

• Lectin pathway

• MAC pathway

• Alternative pathway

What is the main similarity between the lectin and classical pathways?

• Both require antibodies

• Both involve C5 activation

• Both form a MAC

• Both start with MBL