his chapter aims to present an overview of yeast cell biology, biochemical structure and composition of cell walls in various
yeast species, septal pore ultrastructure, and other subcellular characteristics, and a phylogenetic framework to these observations.
Yeast cells have ultrastructural features typical of other eukaryotic cells, which include the presence of membrane-bound
organelles. Through the use of microscopic techniques, yeast cells have been the topic of detailed structural research for
many decades. Because of their relatively small size, electron microscopy is an essential tool for the study of the cellular
ultrastructure of the cell. Yeast cells contain all subcellular structures typical of eukaryotes. These structures include
the cytoskeleton, a nucleus and various subcellular organelles such as the endoplasmic reticulum (ER), the Golgi apparatus,
mitochondria, and microbodies. Like plants, yeast cells contain a vacuole, and the plasma membrane is surrounded by a rigid
cell wall. However, chloroplasts are absent in all fungi, which include the yeasts. Fluorescence microscopy methods have become
an attractive tool for studying living yeast cells due to the availability of novel fluorescent dyes and the introduction
of genes that encode fluorescent proteins. Upon introduction of hybrid genes encoding a fluorescent protein fused to a yeast
protein, any subcellular structure can be specifically marked and its kinetics analyzed in real time in living yeast cells.