In the EMIT system, the absorbance of the product is ______ proportional to the concentration of the unlabeled ligand in the reaction.In the FPIA system, the amount of polarized fluorescent light produced by the reaction is ______ proportional to the concentration of the unlabeled ligand in the reaction.

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Quizplus · Accepted Answer

With the EMIT system, as unlabeled ligand increases, there will be greater competition for antibody binding sites between unlabeled ligand and labeled ligand, freeing more labeled ligand.Free, labeled ligand will react to produce a product which is measurable by spectrophotometry and is in direct proportion to the amount of unlabeled ligand introduced into the reaction by the patient sample.With FPIA, there is also competition between labeled ligand and unlabeled ligand for antibody binding sites.In FPIA, the more unlabeled ligand present, the less labeled ligand bound in the ligand-antibody complex.It is the labeled ligand-antibody complex that produces fluorescence polarization.Thus the more unlabeled ligand present in the patient sample, the more binding of unlabeled ligand to the antibody, resulting in less labeled ligand binding to antibody.This will result in less production of polarized fluorescent light, an inverse relationship.

In the EMIT System, the Absorbance of the Product Is