The use of antibodies in the ELISA test
The ELISA test uses antibodies to detect whether a specific protein or pathogen is present in a sample. A colour change signals a positive result.
Real World
HIV diagnosis in clinics worldwide uses an ELISA test on a blood sample; if antibodies to HIV antigens are present, the enzyme-linked secondary antibody produces a colour change, confirming infection within hours.
Exam Focus
Sequence the ELISA steps in order (antigen → primary antibody → secondary antibody → colour change) — marks follow the correct logical order.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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