MYCOLOGY DOWNLOAD AS [PDF]. CLICK HERE Yeasts and Molds These fungi grow as saprophytes, parasites, or both by using specific proteolytic, glycolytic, or lipolytic enzymes to extracellularly break down substrates and to absorb the products of digestion through the fungal cell envelope. Cell Wall The fungal cell wall gives shape and form, protects against mechanical injury, prevents osmotic lysis, and provides passive protection against the ingress of potentially harmful macromolecules. Filamentous Fungi and Filamentous Bacteria Fungi are different from the Actinomycetes, a group of prokaryotic filamentous bacteria having peptidoglycans in their cell walls and an absence of nuclear membranes and organelles, but the two groups of microorganisms are usually considered together in texts. Hyphal and Yeast Morphogenesis Hyphal extension growth occurs apically by a sophisticated organization of tip-growth-related organe...