3.2.4 | CELL RECOGNITION AND THE IMMUNE SYSTEM

Question 1

what is an antigen

Answer 1

protein on cell surface membrane which triggers an immune response

Question 2

what type of cells and molecules can the immune system identify

Answer 2

pathogens
cells from other organisms
abnormal body cells
toxins

Question 3

describe phagocytosis of pathogens

Answer 3

phagocyte recognises antigens on pathogen
phagocyte engulfs pathogen by surrounding it with its cell membrane
pathogen contained in vesicle forming a phagosomes in cytoplasm of phagocyte
lysosome fuses with phagosome and releases lysozymes
lysozymes hydrolyse/digest pathogen

Question 4

what are antibodies

Answer 4

quaternary structure proteins (4 polypeptide chains)
secreted by B lymphocytes eg. plasma cells in response to specific antigens
bind specifically to antigens forming antigen-antibody complexes

Question 5

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