Dividing yeast cells. Coloured scanning electron micrograph (SEM) of Schizosaccharomyces pombe yeast cells dividing. S. pombe is a single-celled fungus that is studied widely as a model organism for eukaryotic cell division. It is a rod-shaped yeast that grows by elongation at its ends. It replicates by binary fission. When it reaches a certain size its genetic material (deoxyribonucleic acid, DNA) separates to opposite ends of the cell and a division septum (wall) grows across the centre of the cell, dividing it into two daughter cells that are identical to the parent cell. Magnification: x2000 when printed 10cm wide.