1. A person who or animal that harbors a specific infectious agent in the absence of discernible clinical disease and serves as a potential source of infection.
2. Any chemical capable of accepting an atom, radical, or subatomic particle from one compound, then passing it to another; cytochromes are electron carriers; homocysteine is a methyl carrier.
3. A substance that, by having chemical properties closely related to or indistinguishable from those of a radioactive tracer, is thus able to carry the tracer through a precipitation or similar chemical procedure; the best carriers are the nonradioactive isotopes of the tracer in question.
4. A large immunogen (usually a protein) that, when coupled to a hapten, facilitates an immune response to the hapten.
5. A component of a membrane that causes the transfer of a substance from one side of the membrane to the other.
6. The mobile phase in chromatography.
7. A component of a biologic fluid that binds a ligand and transports that ligand to a ne wlocation.
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