Monoclonal antibodies to locate molecules in cells
Infection and response • Monoclonal antibodies (biology only) (HT only)
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Definition and principle
Monoclonal antibodies are identical copies of a single antibody that recognise one specific antigen shape. The antibody–antigen binding is highly specific, so an antibody directed at a target molecule binds that molecule in a mixture of many different molecules. Binding of a labelled monoclonal antibody to its target therefore reveals the presence and location of the molecule in a cell or tissue sample .
How labelling produces a visible signal
An antibody is chemically linked to a detectable label (fluorescent dye, enzyme or radioactive tag). The antibody binds the target molecule; the attached label produces a visible or measurable signal where the antibody binds. Cause → effect: antibody binds antigen → label accumulates at antigen site → microscope or instrument detects the label and identifies the molecule's location.
Common research techniques using monoclonal antibodies
Monoclonal antibodies function as the probe in multiple laboratory methods that locate or measure molecules in cells and tissues. Typical applications include microscopy-based localisation in tissue sections and cells, detection of specific proteins in extracts, and sorting or quantifying labelled cells. The general principle and wide use of antibody-based detection in tests and biomedical work is described in the course text, and production of monoclonal antibodies uses hybridoma technology involving mouse spleen cells fused with myeloma cells .
Production link to research use
Monoclonal antibodies originate from hybridoma cells made by fusing antibody-producing spleen cells with myeloma cells. Hybridoma cells grow indefinitely and secrete identical antibodies into culture medium; antibodies are collected and purified for lab use. Cause → effect: antigen injection into an animal stimulates specific antibody production → spleen cells provide antibody genes → fusion with myeloma cells forms hybridomas → hybridomas produce large amounts of identical antibodies for research or diagnostics .
Limitations and factors that affect use
Monoclonal antibody binding requires that the target antigen retains its recognised shape after sample preparation. Fixation, denaturation or masking of the antigen can prevent binding. Cross-reactivity with similar molecules can produce false positives. Production costs and ethical issues related to animal use can limit availability. Cause → effect: improper sample processing → altered antigen shape → reduced antibody binding and unreliable localisation results.
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