In mushrooms the basidia are found along the gills or pores on the underside of the cap. Some mushrooms produce toxins that are lethal to humans. Glomeromycota mycorrhizae Most are mycorrhizal fungi that form a mutualistic symbiosis with the roots of plants. Microsporidia Obligate intracellular parasites of fish, humans and insects. Rachel Watson, M. AG Cell: rwatson uwyo. Classification of Fungi Fungi have been classically characterized and classified by the appearance of their colony color, size, etc , hyphal organization septate or coenocytic , and the structure and organization of reproduction spores.
Ascomycetes also cause plant diseases, including ergot infections, Dutch elm disease, and powdery mildews. This and other Saccharomyces species are used for brewing beer. Figure 7. The life cycle of an ascomycete is characterized by the production of asci during the sexual phase.
The haploid phase is the predominant phase of the life cycle. The Basidiomycota basidiomycetes are fungi that have basidia club-shaped structures that produce basidiospores spores produced through budding within fruiting bodies called basidiocarps Figure 8. They are important as decomposers and as food. This group includes rusts, stinkhorns, puffballs, and mushrooms. Several species are of particular importance. Cryptococcus neoformans , a fungus commonly found as a yeast in the environment, can cause serious lung infections when inhaled by individuals with weakened immune systems.
The edible meadow mushroom, Agricus campestris , is a basidiomycete, as is the poisonous mushroom Amanita phalloides , known as the death cap.
The deadly toxins produced by A. Figure 8. The life cycle of a basidiomycete alternates a haploid generation with a prolonged stage in which two nuclei dikaryon are present in the hyphae. Finally, the Microsporidia are unicellular fungi that are obligate intracellular parasites. They lack mitochondria, peroxisomes, and centrioles, but their spores release a unique polar tubule that pierces the host cell membrane to allow the fungus to gain entry into the cell.
A number of microsporidia are human pathogens, and infections with microsporidia are called microsporidiosis. One pathogenic species is Enterocystozoan bieneusi , which can cause symptoms such as diarrhea, cholecystitis inflammation of the gall bladder , and in rare cases, respiratory illness.
Histoplasma capsulatum Aspergillus niger Basidiomycota Basidia. Amanita phalloides Cryptococcus neoformans Amanita phalloides Microsporidia Lack mitochondria, peroxisomes, and centrioles.
Spores produce a polar tube Enterocystozoan bieneusi Enterocystozoan bieneusi Microsporidia unidentified Zygomycota Mainly saprophytes. Zygospores Rhizopus stolonifera Mucor spp. Rhizopus sp. Think about It Which group of fungi appears to be associated with the greatest number of human diseases? Eukaryotic Pathogens in Eukaryotic Hosts When we think about antimicrobial medications, antibiotics such as penicillin often come to mind.
Penicillin and related antibiotics interfere with the synthesis of peptidoglycan cell walls, which effectively targets bacterial cells. These antibiotics are useful because humans like all eukaryotes do not have peptidoglycan cell walls. Developing medications that are effective against eukaryotic cells but not harmful to human cells is more difficult.
Despite huge morphological differences, the cells of humans, fungi, and protists are similar in terms of their ribosomes, cytoskeletons, and cell membranes. As a result, it is more challenging to develop medications that target protozoans and fungi in the same way that antibiotics target prokaryotes.
Fungicides have relatively limited modes of action. Because fungi have ergosterols instead of cholesterol in their cell membranes, the different enzymes involved in sterol production can be a target of some medications.
The azole and morpholine fungicides interfere with the synthesis of membrane sterols. These are used widely in agriculture fenpropimorph and clinically e. Some antifungal medications target the chitin cell walls of fungi.
Despite the success of these compounds in targeting fungi, antifungal medications for systemic infections still tend to have more toxic side effects than antibiotics for bacteria. Anthony is relieved the ringworm is not an actual worm, but wants to know what it really is. The physician explains that ringworm is a fungus. He tells Anthony that he will not see mushrooms popping out of his skin, because this fungus is more like the invisible part of a mushroom that hides in the soil.
While not all fungi form mushrooms, most do form a network of hyphae, tube-like structures that allow the fungus to search out and absorb new food sources. Non-septate hyphae are generally single-cell organisms.
A fungus starts from a spore and the initial hypha grows out from that germ. The first hypha grows out, extending at the tip, or apex, and then begins to branch out into richer areas of food, forming a body of hyphae, the mycelium.
The hyphae exude digestive enzymes and absorb nutrients. As the mature fungus exhausts its food supply, it cannibalizes old hyphae and expands. Hyphae form more branches in areas that are richer in nutrients. Depending on the type of fungus, hyphae can be one large multi-nucleated cell, when they are called non-septate hyphae, or can have dividers between the individual cells, when they are called sepate hyphae. Septate hyphae have dividers between the cells, called septa singular septum.
The septa have openings called pores between the cells, to allow the flow of cytoplasm and nutrients throughout the mycelium. Hence, partitions or distinct cells are not present in aseptate hyphae. Due to the absence of cross walls, there are many nuclei together in aseptate hyphae. Thus, aseptate hyphae are generally multinucleated.
Primitive fungi mostly possess aseptate hyphae. Zygomycetes fungi are aseptate fungi. Furthermore, Mucor and Pythium are two more genera of aseptate fungi. Septate hyphae consist of septa between cellular compartments while aseptate hyphae lack septa or cross walls. So, this is the key difference between septate and aseptate hyphae.
Furthermore, septate hyphae are an advanced form of hyphae which is at low risk of damaging the entire fungus upon damage to a hypha while aseptate hyphae are a form of primitive hyphae that is at a higher risk of damaging the entire fungus upon damage to a hypha. Therefore, this is also a difference between septate and aseptate hyphae.
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