CHARACTERISTICS OF FUNGIb. Yeasts—nonfilamentous, unicellular fungi that are spherical or oval in shape. They are widely distributed in nature and may make a white powdery coating on fruits and leaves. Some yeasts undergo binary fission to produce two cells of equal size and are called fission yeasts. Others, such as Saccharomyces reproduce by budding. The parent cell forms a bulge on the surface. The nucleus divides and one nucleus migrates into the bud. The cell wall divides the bud from the parent, and the bud eventually breaks away. One yeast cell can produce as many as 24 daughter cells by budding. Some yeasts produce buds that do not break away, and form a short chain of cells called a pseudohypha. Candida albicans, which causes thrush and vaginitis in humans, uses pseudohyphae to invade deeper into tissues. Growing on lab media, yeasts produce colonies similar in appearance to bacterial colonies.
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