False-colour scanning electron micrograph (SEM) of yeast cells, Saccharomyces cerevisiae, commonly known as baker's yeast. Yeast is a kind of single- celled fungus. It is able to ferment sugar, producing alcohol & carbon dioxide in the process. It has long been used in the brewing of beer, the production of wine & in the baking of leavened bread (carbon dioxide causes the dough to rise). Medically, dried yeast is used as a source of vitamin B1, riboflavin, & nicotinic acid. Yeast cells divide rapidly by budding off new cells (visible here). They can also reproduce sexually. Magnficiation: x370 at 35mm size. Gold tint. Original is BW B250/171. Reference: MICROCOSMOS, figure 5.37, page 107.