Topic 2.? Immunity

Question 1

Describe how phagocytic cells destroy bacteria

Answer 1

• Phagocyte is attracted to chemical product of bacteria
• The phagocyte engulfs bacteria
• A vacuole forms around the bacteria
• Lysosome fuses with the vacuole
• Bacteria is hydrolysed

Question 2

Explain how vaccines protect people against diseases

Answer 2

• Vaccine contains weakened pathogens
• This stimulates immune
response, memory cells are made
• On second exposure, memory cells RAPIDLY produce antibodies
• The antibodies destroy the pathogen

Question 3

Describe how vaccination leads to production of antibodies

Answer 3

• Vaccine contains antigen from pathogen
• Macrophage presents antigen on its surface
• T cell with complementary receptor protein binds to antigen
• T cell stimulates B cells with complementary antibody
• B cells secrete large amounts of antibody
• B cells divide to form clones all producing same antibody