immune system and response

• When an antigen is detected, the immune response undergoes four main stages:

  1. phagocytosis of pathogen
  2. activation of T lymphocytes
  3. activation of B lymphocytes
  4. production of antibodies by plasma cells
• • Cellular immune response – includes phagocytosis and T-cell response
  • Humoral immune response – includes B-cells and the antibodies they produce
• antigens are foreign proteins present on the cell surface membrane that stimulate an immune response
• antigenic variability is when antigens mutate so their dna sequence changes so the immune system wont be able to detect newly mutated antigen - this is why some flue virus vaccines are updated every year
• 2 types of lymphocytes or white bloody cells:

  • B cells = mature in bone marrow involved in humoral response
  • T cells = mature in thymus gland involved in cell mediated response
• Describe how bacteria divide:

  1. Binary fission
  2. Replication of (circular) DNA
  3. Division of cytoplasm to produce 2 daughter cells
  4. Each with single copy of (circular) DNA;