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 specific trait, yet does not express the associated phenotype. This means that while the individual carries the genetic information for the recessive trait, it is masked by the presence of a dominant allele.

For example, if we consider the trait for a genetic condition that is recessive, a carrier would have one allele responsible for the condition and one normal allele. Since the normal allele is dominant, the individual does not show the symptoms of the condition. This concept is crucial in understanding how recessive traits can persist in a population, as carriers can pass on the recessive allele to their offspring, potentially leading to the expression of the trait if the offspring inherit two copies of the recessive allele (one from each parent).

Understanding the role of carriers is significant in genetic counseling, family planning, and studying the inheritance patterns of certain diseases.