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 a each type of chlorophyll molecule, and alters the absorption spectrum of light. Chlorophyll "a" has a long hydrophobic tail, which anchors the molecule to other hydrophobic proteins in the thylakoid membrane of the chloroplast. Once detached from the porphyrin ring, this long hydrocarbon tail becomes the precursor of two biomarkers, pristane and phytane, which are important in the study of geochemistry and the determination of petroleum sources. Chlorophyll "a" biosynthetic pathway utilizes a variety of enzymes. Genes code for the enzymes on the Mg-tetrapyrroles of both bacteriochlorophyll "a" and chlorophyll "a". It begins with glutamic acid, which is transformed into