Mitosis in Unicellular Organisms. In unicelullar (single-celled) organisms, mitosis is a common and important form of asexual reproduction. It can also be called binary fission, and plays a role in a similar process called multiple fission.Organisms that reproduce through mitosis make exact copies of themselves.n unicellular organisms such as bacteria, mitosis is a type of asexual reproduction, making identical copies of a single cell. In multicellular organisms, mitosis produces more cells for growth and repair.