What is a 'carrier' in terms of genetics?

In genetics, a 'carrier' refers to an individual who possesses one copy of a recessive allele for a particular trait while having a dominant allele as well. This means that although the individual does not express the recessive trait phenotypically, they can pass the recessive allele on to their offspring. For instance, if the trait in question is a genetic disorder that is recessive, a carrier will not show symptoms of the disorder but can still transmit the allele responsible for it to the next generation.

This concept is fundamental in understanding heredity, particularly in the context of autosomal recessive diseases, where two recessive alleles are necessary for the trait to manifest. Thus, carriers play a crucial role in the inheritance of genetic traits, even if they themselves do not exhibit any signs of being affected.