Genetics is the study of
genes — what they are, what they do, and how they work. Genes are made up of molecules inside the
nucleus of a
cell that are strung together in such a way that the sequence carries
information: that information determines how living
organisms inherit phenotypic traits, (features) determined by the genes they received from their parents and thereby going back through the generations. For example,
offspring produced by
sexual reproduction usually look similar to each of their parents because they have inherited some of each of their parents' genes. Genetics identifies which features are inherited, and explains how these features pass from
generation to generation. In addition to inheritance, genetics studies how genes are turned on and off to control what substances are made in a cell -
gene expression; and how a cell divides -
mitosis or
meiosis.