carrier

1. A person 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; e.g., cytochromes are electron carriers; homocysteine is a methyl c.. 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. SEE ALSO: label, tracer. 4. A large immunogen that, when coupled to a hapten, will facilitate 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.

- amalgam c. an instrument used to transport triturated amalgam to a cavity preparation and to deposit it therein.

- convalescent c. an individual who is clinically recovered from an infectious disease but is still capable of transmitting the infectious agent to others.

- genetic c. a person heterozygous for a mutant allele that, in homozygous form, causes a recessive condition.

- hydrogen c. a molecule that, in conjunction with a tissue enzyme system, carries hydrogen from one metabolite (oxidant) to another (reductant) or to molecular oxygen to form H₂O. SYN: hydrogen acceptor.

- incubatory c. an individual capable of transmitting an infectious agent to others during the incubation period of the disease.

- latent c. a person, typically a prospective parent, bearing the appropriate genotype of a trait (homozygous for recessive, homozygous or heterozygous for dominant, hemizygous or homozygous for X-linked) that manifests the trait only under certain conditions, e.g., age, an environmental insult, etc.

- manifesting c. SYN: manifesting heterozygote.

- translocation c. a person with balanced translocation.

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car·ri·er 'kar-ē-ər n

1 a) a person, animal, or plant that harbors and transmits the causative agent of an infectious disease esp one who carries the causative agent systemically but is asymptomatic or immune to it <a \carrier of typhoid fever> compare RESERVOIR (2), VECTOR (2)

b) an individual possessing a specified gene and capable of transmitting it to offspring but not expressing or only weakly expressing its phenotype esp one that is heterozygous for a recessive factor

2) a usu. inactive substance used in association with an active substance esp. for aiding in the application of the active substance: as

a) a support for a catalyst

b) a vehicle serving esp. as a diluent (as for an insecticide or a drug)

3) a substance (as a catalyst) by whose agency some element or group is transferred from one compound to another

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n.

1. a person who harbours the microorganisms causing a particular disease without experiencing signs or symptoms of infection and who can transmit the disease to others.

2. (in genetics) a person who bears a gene for an abnormal trait without showing any signs of the disorder; the carrier is usually heterozygous for the gene concerned, which is recessive.

3. an animal, usually an insect, that passively transmits infectious organisms from one animal to another or from an infected animal to a human being. See also vector.

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car·ri·er (karґe-ər) 1. an instrument or apparatus for carrying something. 2. an individual who harbors the specific organisms of a disease without manifest symptoms and is capable of transmitting the infection. 3. a chemical substance that can accept one or more electrons and then donate them to another substance (being reduced and then reoxidized). Called also electron carrier. 4. in genetics, an individual who is heterozygous for a recessive gene and thus does not express the recessive phenotype but can transmit it to offspring. In humans, only females can be carriers of X-linked recessive traits. 5. a substance that carries a radioisotopic or other label, as in a tracer study. A second isotope mixed with a particular isotope is also referred to as a carrier; see carrier-free. 6. a transport protein that attaches to and carries a specific substance, particularly one that transports the substance across the cell membrane. 7. in immunology, a macromolecular substance to which a hapten is coupled in order to produce an immune response against the hapten, immune responses being usually produced only against large molecules capable of simultaneously binding both B cells and helper T cells. Called also Schlepper.