GradeGen

The ability of an antibody to bind to one particular target because their shapes are complementary.

The matching of an enzyme's active site to a particular substrate because their shapes are complementary.

The active site's shape gives an enzyme its specificity: a substrate with the wrong shape will not bind successfully. The enzyme's molecular structure therefore determines which reaction it can catalyse. The lock-and-key model is a simplified way to represent this relationship; the enzyme is compared with a lock and the matching substrate with its key.

Link every advantage to specificity: the antibody binds to a complementary target on particular cells, so fewer healthy cells are exposed or damaged.

The ability of a diagnostic test to identify the intended target without also giving positive results for unrelated substances.

A test with high specificity is unlikely to confuse the intended target with a different molecule, reducing false positive results. A test with high sensitivity can detect a small amount of the target, reducing the chance that an affected person receives a false negative result because the concentration is low.

Specificity

Definition

How each exam board covers it

AQA GCSE Biology · 8461

Edexcel GCSE Biology · 1BI0

Exam tips

Revise Biology with GradeGen

OCR GCSE Biology B · J257