Definition: In the context of genetics, a reagent is a biological substance that can be used to transfer genetic material from one organism to another. In the field of molecular biology, a reagent is used to transfer genetic information between two organisms or between two different species. For example, in the study of genetics, researchers may use a reagent to transfer DNA fragments from one cell to another for cloning purposes. In biotechnology, a reagent can be used to manipulate genes in living cells to produce desired