OpenRevise

Biology · Monoclonal Antibodies

Knowledge organiser

The whole chapter on one page. Print it on A4 — it is already landscape — or cover a box and see how much of it you can say from memory.

Back to the chapter

Biology · AQA Paper 1

Monoclonal Antibodies

Producing Monoclonal Antibodies (Separate only)

A monoclonal antibody comes from one clone of cells, so every antibody is identical and targets the same chemical.

  • Monoclonal antibody An antibody made by a single clone of cells, which is specific to one binding site on one antigen.
  • Hybridoma cell A cell formed by combining a lymphocyte with a tumour cell, which can both divide and make an antibody.
  • Lymphocyte A white blood cell that makes antibodies.
A five-step flow from injecting a mouse with an antigen to collecting lymphocytes, making hybridoma cells, cloning them and purifying the monoclonal antibody.
A hybridoma cell can both divide and make the antibody.

Lymphocytes, tumour cells and hybridoma cells compared

  • Lymphocyte and tumour cell A lymphocyte makes the antibody but cannot divide for long; A tumour cell divides over and over but makes no useful antibody; Neither is any use for making large amounts on its own
  • Hybridoma cell Made by combining the two; Makes the specific antibody; Divides again and again

Making monoclonal antibodies

  • Stimulate the lymphocytes A mouse is injected with the antigen.
  • Collect the lymphocytes Lymphocytes that make the antibody are taken from the mouse.
  • Make hybridoma cells The lymphocytes are combined with a particular kind of tumour…
  • Select and clone Single hybridoma cells that make the right antibody are picked out and cloned.

Uses of Monoclonal Antibodies (Separate only)

A monoclonal antibody finds one target, and whatever it carries goes only to that target.

  • Pregnancy test A test that uses monoclonal antibodies to detect the hormone hCG in urine.
  • hCG The hormone that is present in the urine of a pregnant woman.
  • Fluorescent dye A dye that glows under certain light, used to show where an antibody has bound.
A pregnancy test strip showing urine carrying hCG and blue-bead antibodies along the strip to a test line, where fixed antibodies capture them and a blue line appears.
The test line only turns blue if the hormone hCG is present in the urine.

Advantages and disadvantages

  • Advantages Very specific, so they target only one chemical; Can deliver drugs straight to cancer cells without harming other cells; Can be used in quick, simple tests such as pregnancy tests
  • Disadvantages They create more side effects than expected; They are expensive to make; Some patients react badly, and mice are used to make them

How a pregnancy test works

  • Urine applied The urine soaks into the strip and picks up antibodies that…
  • Hormone binds If hCG is present, it binds to the mobile antibodies.
  • Capture at the test line Further along the strip, fixed antibodies on the test line bind…
  • The control line Antibodies on the control line bind the mobile antibodies…