Disease and response · GCSE Biology
Monoclonal antibodies
Explain how monoclonal antibodies are made and used for GCSE Biology: hybridoma cells, pregnancy tests and targeted cancer therapy.
Fuse mouse B-cell with tumour cell → hybridoma → clones make one identical antibody. Pregnancy test: anti-hCG binds; cancer: antibody carries drug to tumour antigen.
The important bits
What you need to know
- 1
Monoclonal antibodies are identical antibodies produced from a single clone of cells, all binding to the same specific antigen.
- 2
To make them, a mouse is injected with a target antigen. B-lymphocytes that produce the desired antibody are collected from the spleen.
- 3
These B-cells are fused with myeloma (tumour) cells to form hybridoma cells that divide indefinitely and secrete antibody.
- 4
Hybridoma cells are cloned and cultured in large fermenters to produce large quantities of one specific monoclonal antibody.
- 5
Pregnancy tests use monoclonal antibodies against human chorionic gonadotrophin (hCG), a hormone in the urine of pregnant women.
- 6
On a pregnancy test stick, mobile antibodies bind hCG and move to a test line where fixed antibodies capture the complex, producing a coloured line.
- 7
In cancer treatment, monoclonal antibodies can be made to bind to antigens on tumour cells. They may block cell signals, flag cells for the immune system, or carry radioactive or toxic drugs directly to cancer cells.
- 8
Monoclonal antibodies are specific (fewer side effects on healthy cells than some chemotherapy) but expensive to produce and can cause immune reactions because they were originally from mice.
Quotations worth analysing
Short evidence. Real method.
“Monoclonal antibodies are produced from a single clone of cells and bind to one specific antigen.”
“Single clone” and “one antigen” define monoclonal. Polyclonal mixes are not monoclonal.
“Hybridoma cells combine the ability to divide indefinitely with antibody production.”
Tumour cell gives division; B-cell gives antibody specificity. Name both parents.
“Monoclonal antibodies can target cancer cells while sparing many healthy cells.”
Specificity is the advantage. Still mention cost and possible side effects in evaluation.
Go deeper
Why fuse a B-cell with a cancer cell?
Normal B-lymphocytes do not divide for long in culture. Myeloma cells divide endlessly but make no useful antibody. Hybridoma inherits both: unlimited division and antibody secretion. Cloning picks one hybridoma making exactly the antibody you want. Fermenters then scale up production. In exams, list stages in order: inject antigen → collect B-cells → fuse → select hybridoma → clone → culture. Missing “clone” loses a step mark.
Go deeper
How a pregnancy test works
hCG appears in urine soon after implantation. Mobile anti-hCG antibodies (linked to coloured particles) move up the strip by capillary action. If hCG is present, it binds these antibodies. At the test line, fixed anti-hCG captures the antibody–hCG complex, trapping colour = positive line. A control line with anti-mouse antibody captures excess mobile antibody to show the test ran correctly. No hCG: colour may not stick at test line, but control should still appear. Specificity means few false positives from other proteins.
Go deeper
Cancer targeting and evaluation
Tumour cells often display antigens not found on normal cells (or in much higher amount). Monoclonal antibody binds that antigen. Therapies include: blocking growth factor receptors; delivering a toxin or radioactive isotope attached to the antibody; triggering immune destruction. Advantages: targeted delivery, less harm to dividing healthy cells than blanket chemotherapy. Disadvantages: cost, time to develop, possible allergic response, not all cancers have a suitable antigen. Balanced GCSE answers need one benefit and one limitation with biological reasoning.
See the idea in action
Describe how monoclonal antibodies are used in a pregnancy test (3 marks). Urine may contain hCG if the woman is pregnant. Monoclonal antibodies on the test stick bind specifically to hCG. Bound antibody–hCG complexes are trapped at the test line, producing a visible coloured line. A control line confirms the test worked.
Exam technique
Turn knowledge into marks
For production, name hybridoma and cloning. For uses, name the antigen (hCG or tumour antigen) and what binding achieves. Evaluation: specific but expensive.
Common mistakes
Do not give these marks away
- 01
Saying monoclonal antibodies are antibiotics or kill bacteria directly without naming the target antigen.
- 02
Omitting the fusion step or confusing B-cells with phagocytes.
- 03
Describing pregnancy tests as detecting “any hormone” rather than hCG specifically.
What are hybridoma cells?
ARed blood cells fused with platelets
BB-lymphocytes fused with tumour cells that produce monoclonal antibodies
CPhagocytes that engulf pathogens
DVaccines containing weakened viruses
Show the answer
B-lymphocytes fused with tumour cells that produce monoclonal antibodies. Hybridomas combine unlimited division from myeloma cells with antibody production from B-cells, allowing mass production of one specific antibody.
Quick questions
If this is the bit you searched
What is a monoclonal antibody?
An identical antibody from a single clone of cells, all specific to one antigen.
How are monoclonal antibodies produced?
B-cells making the desired antibody are fused with tumour cells to form hybridomas, which are cloned and cultured in fermenters.
How do pregnancy tests use monoclonal antibodies?
They bind hCG in urine. A coloured line appears when antibody–hCG complexes are trapped at the test line.
How can monoclonal antibodies treat cancer?
They bind antigens on tumour cells to deliver drugs or radiation directly, or to help the immune system attack the cancer.