What are monoclonal antibodies, how are they made, and what are they used for?
How monoclonal antibodies are produced from a single clone of cells, their specificity to one binding site, and their uses in pregnancy tests, diagnosis, research and treating disease, with the advantages and disadvantages.
A focused answer to AQA GCSE Biology 4.3.1.7, covering how monoclonal antibodies are produced from hybridoma cells, their specificity, and their uses in pregnancy tests, diagnosis, research and treatment.
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What this dot point is asking
This higher-tier dot point asks you to explain how monoclonal antibodies are produced from a single clone of cells, why they are specific to one binding site, and to describe their uses and weigh up their advantages and disadvantages.
How monoclonal antibodies are made
The production steps:
- A mouse is injected with the chosen antigen, so it makes the matching lymphocytes (white blood cells that produce the antibody).
- The lymphocytes are taken and combined (fused) with a kind of fast-dividing tumour cell to make a hybridoma cell.
- The hybridoma cell can both make the antibody and divide rapidly, so it is cultured to divide many times, producing large amounts of the antibody, which is then collected and purified.
A tumour cell is used because normal lymphocytes do not divide well outside the body, whereas tumour cells divide rapidly, so fusing the two gives a cell that makes the antibody and multiplies.
Uses of monoclonal antibodies
In a pregnancy test, monoclonal antibodies on the test strip bind to HCG; a second set of antibodies, attached to a coloured dye, then bind and produce a coloured line, which shows the test works by specific antibody-antigen binding.
Advantages and disadvantages
- Advantages: they are highly specific, binding only to the target, so they can be used to deliver treatment directly to diseased cells, reducing harm to healthy cells. They can detect very small amounts of a substance, making them useful in diagnosis.
- Disadvantages: they produced more side effects than expected when first used to treat disease, so they are not yet as widely used as hoped. They are also expensive and difficult to produce, and producing them involves the use of animals (mice), which some people object to.
Try this
Q1. Explain why monoclonal antibodies are described as specific. [1 mark]
- Cue. They are made from a single clone of cells, so they all bind to one particular antigen or binding site.
Q2. Describe how a hybridoma cell is made. [2 marks]
- Cue. A lymphocyte that makes the wanted antibody is combined with a fast-dividing tumour cell.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20194 marksDescribe how monoclonal antibodies are produced from a single clone of cells.Show worked answer →
A 4-mark higher-tier describe question rewards the production steps in order.
A mouse is injected with the chosen antigen, so its lymphocytes make the required antibody. These lymphocytes are taken and combined (fused) with a fast-dividing tumour cell to make a hybridoma cell. The hybridoma cell can both make the antibody and divide rapidly, so it is cultured to divide many times, producing large amounts of identical (monoclonal) antibody, which is then collected and purified.
Markers reward injecting the antigen into a mouse, fusing a lymphocyte with a tumour cell to form a hybridoma, the hybridoma dividing to make many antibodies, and collecting and purifying them.
AQA 20223 marksExplain how a monoclonal antibody can be used to deliver a drug directly to cancer cells, and give one advantage of this method over standard chemotherapy.Show worked answer →
A 3-mark question rewards the targeting mechanism plus an advantage.
Cancer cells have specific antigens on their surface. A monoclonal antibody is made that is specific to (binds to) these cancer-cell antigens, and a drug (or toxin or radioactive substance) is attached to the antibody. When injected, the antibody travels through the body and binds only to the cancer cells, delivering the drug straight to them.
The advantage is that the drug is targeted to the cancer cells, so it harms fewer healthy cells than standard chemotherapy, which affects all dividing cells and causes more side effects.
Markers reward the antibody binding to antigens on the cancer cells, carrying a drug to them, and reduced harm to healthy cells.
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Sources & how we know this
- AQA GCSE Biology (8461) specification — AQA (2016)