Fungus commonly known as sac fungi or ascomycetes, constitute the largest taxonomic group within the Eumycota. These fungi form meiotic spores called ascospores, which are enclosed in a special sac-like structure called an ascus. This phylum includes morels, a few mushrooms and truffles, unicellular yeasts (e.g., of the genera "Saccharomyces", "Kluyveromyces", "Pichia", and "Candida"), and many filamentous fungi living as saprotrophs, parasites, and mutualistic symbionts (e.g. lichens). Prominent and important genera of filamentous ascomycetes include "Aspergillus", "Penicillium", "Fusarium", and "Claviceps". Many ascomycete species have only been observed undergoing asexual reproduction (called anamorphic species), but analysis of molecular data has often been
Chlorophyll the last step, the conversion of protochlorophyllide to chlorophyll, is light-dependent and such plants are pale (etiolated) if grown in darkness. Non-vascular plants and green algae have an additional light-independent enzyme and grow green even in darkness. Chlorophyll itself is bound to proteins and can transfer the absorbed energy in the required direction. Protochlorophyllide occurs mostly in the free form and, under light conditions, acts as a photosensitizer, forming highly toxic free radicals. Hence, plants need an efficient mechanism of regulating the amount of chlorophyll precursor. In angiosperms, this is done at the step of aminolevulinic acid (ALA), one of