MICR 270 Module 3 Exam Questions With
Accurate Answers
Steps of the Adaptive Immune Response - ANSWER 1. Antigen recognition/presentation
2. Lymphocyte activation
3. Elimination of pathogens
4. Contraction (apoptosis of immune cells)
5. Establishment of immunological memory
Clonal Expansion - ANSWER Production of a large quantity of identical cells from the
same original cell
Apoptosis - ANSWER Programmed cell death controlled by the cell itself, generates
almost no damage to the surrounding area
MHC I - ANSWER CD8 CTLs
MHC II - ANSWER CD4 helper T-cells
Antigen-Presenting Cells (APCs) - ANSWER Helper T-cells critical as T-cells alone cannot
recognize extracellular pathogens and require an intermediate (i.e. APC) to present them
APCs internalize pathogens via phagocytosis or receptor-mediated endocytosis, process
, them into peptides (antigens) to be displayed on the cell surface
Professional APCs - ANSWER Macrophages, B-cells, dendritic cells* (most effective)
MHC II
Express costimulatory molecules to activate helper T-cells
Non-professional APCs - ANSWER Glial cells, fibroblasts
Other cells rarely needed for this function, only for short periods in the case of a
sustained inflammatory response
Formation of Cell Surface Peptide:MHC Complex After APCs - ANSWER 1. Endogenous
-> peptide:MHC I (CD8 CTLs)
2. Exogenous -> peptide: MHC II (CD4 helper T-cells), leads to humoral immunity
Exogenous Pathway - ANSWER 1. Antigen engulfment
2. Proteolytic processing: protease cleaves bonds of antigens inside endosomes to
modify its action
3. Formation of MHC-antigen complex: vesicle containing antigen fragments fuses with
vesicles containing MHC molecules that originate from the ER via Golgi
4. Cell surface expression: MHC-antigen complex transported to plasma membrane
5. Recognition by helper T-cell: TCR binds to MHC-antigen complex on APC which
initiates the adaptive immune response
Accurate Answers
Steps of the Adaptive Immune Response - ANSWER 1. Antigen recognition/presentation
2. Lymphocyte activation
3. Elimination of pathogens
4. Contraction (apoptosis of immune cells)
5. Establishment of immunological memory
Clonal Expansion - ANSWER Production of a large quantity of identical cells from the
same original cell
Apoptosis - ANSWER Programmed cell death controlled by the cell itself, generates
almost no damage to the surrounding area
MHC I - ANSWER CD8 CTLs
MHC II - ANSWER CD4 helper T-cells
Antigen-Presenting Cells (APCs) - ANSWER Helper T-cells critical as T-cells alone cannot
recognize extracellular pathogens and require an intermediate (i.e. APC) to present them
APCs internalize pathogens via phagocytosis or receptor-mediated endocytosis, process
, them into peptides (antigens) to be displayed on the cell surface
Professional APCs - ANSWER Macrophages, B-cells, dendritic cells* (most effective)
MHC II
Express costimulatory molecules to activate helper T-cells
Non-professional APCs - ANSWER Glial cells, fibroblasts
Other cells rarely needed for this function, only for short periods in the case of a
sustained inflammatory response
Formation of Cell Surface Peptide:MHC Complex After APCs - ANSWER 1. Endogenous
-> peptide:MHC I (CD8 CTLs)
2. Exogenous -> peptide: MHC II (CD4 helper T-cells), leads to humoral immunity
Exogenous Pathway - ANSWER 1. Antigen engulfment
2. Proteolytic processing: protease cleaves bonds of antigens inside endosomes to
modify its action
3. Formation of MHC-antigen complex: vesicle containing antigen fragments fuses with
vesicles containing MHC molecules that originate from the ER via Golgi
4. Cell surface expression: MHC-antigen complex transported to plasma membrane
5. Recognition by helper T-cell: TCR binds to MHC-antigen complex on APC which
initiates the adaptive immune response
