Vegetative Organization
Yeasts are commonly egg-shaped, but some are spherical, lemon-shaped, pear-shaped, cylindrical, triangular, or even elongated forming false mycelium called pseudomycelium.

In general, they are larger than most largest bacteria. Yeasts considerably range from 1-5 µ m in width and from 5-30 µ m or more in length.

Yeasts can be differentiated from bacteria in that they are generally large in size, have distinct morphological characters and have chitin in their cell walls; from algal protists in that they do not have photosynthetic pigments and from protozan protists in that they have a rigid cell wall.