MHC Pathways and Antigen Presentation

The video explains the adaptive immune response, focusing on antigen processing and presentation pathways. It details the roles of MHC class I and II molecules in presenting antigens to T cells, enabling immune responses. The process involves acquiring antigens, tagging them for proteolysis, and presenting them on cell surfaces. MHC class I molecules present intracellular antigens, while MHC class II molecules present extracellular antigens. The video also covers the structural differences between MHC classes and their specific functions in immune surveillance.

What is the primary role of antigen processing and presentation pathways in adaptive immune responses?

• To produce antibodies

• To ensure MHC molecules are loaded with appropriate ligands

• To destroy pathogens directly

• To activate B cells directly

Which cells are activated by MHC molecules expressed on antigen-presenting cells?

• Neutrophils

• B cells

• T cells

• Macrophages

What is the main source of peptides presented by MHC class I molecules?

• Old proteins

• Bacterial proteins

• Defective ribosomal translation products

• Extracellular antigens

What is the role of the transporter associated with antigen processing (TAP) in the MHC class I pathway?

• To degrade proteins

• To transport MHC molecules to the Golgi

• To translocate peptides into the ER lumen

• To fold MHC molecules

What assists in the folding and assembly of MHC class I molecules in the ER lumen?

• Cytosolic proteins

• Golgi enzymes

• ER chaperones

• Proteasomes

Where are MHC class II molecules primarily expressed?

• Professional antigen-presenting cells

• Red blood cells

• All nucleated cells

• Muscle cells

What is the typical length of peptides bound by MHC class II molecules?

• 8-10 amino acids

• 5-8 amino acids

• 15-20 amino acids

• 10-15 amino acids

What is the role of the invariant chain in MHC class II molecules?

• To prevent premature peptide loading

• To degrade peptides

• To transport peptides to the ER

• To assist in peptide binding

How are extracellular antigens processed for presentation by MHC class II molecules?

• In the Golgi apparatus

• In endosomes

• In the ER

• In the cytosol

What is the final destination of MHC class II molecules after processing?

• Mitochondria

• Nucleus

• Plasma membrane

• Cytosol