Describe how phagocytosis of a virus leads to presentation of its antigens (3 marks)
Virus engulfed by phagocyte (broad immune response), destroyed using lysosomes (hydrolysis) and viral antigens presented on cell membrane (trigger specific immune response e.g. anti-bodies).
Steps of phagocytosis:
1.Phagosome/vesicle fuses with lysosome (1 mark)2.(Virus) destroyed by lysozymes/hydrolytic enzymes (1 mark)3.Peptides/antigen (from virus) are displayed on the cell membrane (1 mark)
Analogy to remember:Operates like packman
Exam technique:Emphasise importance of key terms e.g. "Fusion with phagosome", "Virus hydrolysed, "antigens on cell membrane" in achieving full marks in regard to A-level mark-schemes (e.g. AQA, OCR Edexcel).
BJ
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