This memory aid covers Memory Aids within Monoclonal Antibodies for GCSE Biology. Production and medical applications of identical antibodies, hybridoma cells, diagnostics It is section 13 of 17 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
Topic position
Section 13 of 17
Practice
15 questions
Recall
18 flashcards
Memory Aids
Hybridoma production — five steps:
- 1. Immunise — inject mouse with target antigen
- 2. Extract — remove B cells from mouse spleen
- 3. Fuse — B cells + myeloma cells = hybridoma cells
- 4. Select — grow hybridoma cells in selective medium; clone
- 5. Produce — mass produce identical monoclonal antibodies
"MONO-clonal" = ONE clone = identical: The prefix "mono" means one. All monoclonal antibodies come from a single clone of hybridoma cells, so they are all identical with the same antigen-binding region. This specificity is the key advantage over polyclonal antibodies.
Pregnancy test mechanism: hCG (pregnancy hormone) in urine → binds to free antibodies with colour marker → complex travels to test line → captured by immobilised anti-hCG antibodies → coloured line appears. No hCG → no binding at test line → no coloured line. Control line always appears if test ran correctly.
Cancer treatment — "smart bombs": Monoclonal antibodies can be thought of as guided missiles that find specific cancer cells by their surface antigens and deliver a drug or flag them for immune system destruction, while leaving normal cells unharmed. This is the key advantage over traditional chemotherapy, which damages all rapidly dividing cells.
Quick Check: Explain why hybridoma cells are used in monoclonal antibody production rather than just using B lymphocytes from the immunised mouse.
B lymphocytes naturally produce specific antibodies against the target antigen after immunisation. However, B lymphocytes cannot survive and divide indefinitely in laboratory culture — they die within days, severely limiting antibody production. Myeloma cells are cancer cells that can divide indefinitely and survive in culture, but they do not produce specific antibodies. By fusing B cells with myeloma cells, hybridoma cells are created that combine the useful properties of both: the ability to produce specific antibodies (from the B cell) and the ability to divide indefinitely in culture (from the myeloma cell). This allows unlimited quantities of identical (monoclonal) antibodies to be produced, which would be impossible using B cells alone.
Quick Check: A patient has a type of cancer where the cancer cells produce an unusual surface protein (antigen X) that is not found on normal cells. Describe how monoclonal antibodies could be used to treat this patient, and evaluate one advantage and one disadvantage of this approach.
Treatment: Monoclonal antibodies specific to antigen X would be produced (by immunising a mouse with antigen X, creating hybridoma cells, and mass-producing the specific antibody). The antibodies could be administered to the patient intravenously. They would circulate through the blood, bind specifically to cells displaying antigen X (the cancer cells), and either flag them for destruction by the patient's immune system (opsonisation) or deliver a linked toxic drug directly to the cancer cells. Advantage: The antibodies only bind to cells displaying antigen X. Normal cells (which lack this antigen) are not targeted, so side effects are much fewer than with conventional chemotherapy, which damages all rapidly dividing cells including healthy ones. Disadvantage: Cancer cells are genetically unstable and may mutate, losing or altering antigen X so that the antibodies no longer recognise them. The treatment may become ineffective as the cancer evolves. Additionally, the treatment is expensive to produce and may not be available to all patients.
Quick Check: A pregnancy test gives a positive result (two lines visible). Explain the molecular events on the test strip that produced this result.
The urine applied to the test contains hCG (human chorionic gonadotropin), a hormone produced only during pregnancy. As urine moves along the strip by capillary action, it first encounters free monoclonal antibodies in the conjugate pad. These antibodies are specific to hCG and are attached to coloured particles (usually colloidal gold). The hCG molecules bind to these free antibodies, forming hCG-antibody-colour complexes. These complexes continue moving along the strip and reach the test line, where anti-hCG antibodies are immobilised (fixed) to the membrane. The hCG in the complex binds to these immobilised antibodies, trapping the coloured particles at the test line — producing the first visible coloured line. Excess free antibodies (not bound to hCG) continue moving and are trapped at the control line (which contains antibodies specific to the free antibody), producing the second visible line. Both lines visible = test valid AND positive result (hCG present = pregnant).