Kingdom fungi

The members of the kingdom Fungi are mostly invisible to the human eye and live mostly in soil, dead matter or in symbiosis with plants, animals or other fungi. Fungi that are visible to the naked eye are that way through fruiting, as either mushrooms or molds. In most ecosystems fungi perform an essential role in decomposing organic matter and in the nutrient cycle. All fungi are eukaryotic organisms containing, membrane bound nuclei with chromosomes. Fungi cells also all have cell walls, composed of chitin, a polymer of nitrogen containing sugar. Members of the kingdom can be found in many habitats and survive in intense conditions, even space.

Fungi first developed over 1.2 million years ago and originated as aquatic organisms. Fungi like animals evolved from opisthokonts, organisms that started as single celled spores and propelled themselves with a single posterior flagellum. During the Cambian period some of these spores moved to land and grew into large fungal spores. Finally, by the late Carboniferous era all classes of fungi were present.

Fungi can either be unicellular or multicellular. Most yeasts are single celled, while most molds and other fungi are multicellular. An example of a single celled fungus is Candida albicans, which is a diploid cell that lives in the human mouth and can cause infections if large amounts exist. Most single celled fungi live in colonies. An example of a multicellular fungus is Amanita muscaria, which is a large red mushroom found in temperate conditions and is considered to be poisonous.

Fungi are chemoheterotrophic organisms that require preformed organic compounds as energy. Fungi usually get their energy by decomposing dead matter found in the soil. They do this by breaking down the nutrients found in the dead matter.

Fungi have complete extracellular digestion. This means that fungi live in their food and digest the food that surrounds their bodies. Fungi digest the complex nutrient material around them into simple, absorbable nutrients. This is done through the secretion of enzymes into the extracellular environment.

Fungi have no nervous system, but instead have an endocrine system. This system enables fungi to recognize and react to outside stimuli, in the form of available food sources.

Fungi have no hearts, but they do have a circulatory system made up of masses of connecting hyphae. Hyphae are long, branching filamentous cells surrounded by tubular cell walls. The hyphae grow at the tips and expand into the nutrients the fungi is decomposing. The hyphae assist in nutrient exchange and in nutrient and water absorption. The hyphae make up the circulatory system of fungi, since they are the cells that transport nutrients throughout the organism.

Fungi have no respiratory system, but their cells do go through cellular respiration, since they are heterotrophs.

Fungi reproduce both sexually and asexually. Fungi reproduce asexually via vegetative spores or mycelial fragmentation. Mycelial fragmentation is when a new organism grows from a fragment of the parent fungi. Asexual reproduction in fungi allows for a rapid dispersal and produces populations of fungi that are clones of the original spore. An example of a fungus that reproduces asexually is Conidia, which is an airborne haploid fungal spore. Sexual reproduction in Fungi is done in many different ways depending on the phyla of the species. In all sexually reproducing fungi, individuals combine by cell fusion of vegetative hyphae, which initiates the sexual cycle. An example of a sexually reproducing fungus is Xylaria, a fungi that grows on dead wood.

One example of a fungus is Neurospora crassa, which is a type of red bread mold that has a haploid life cycle. Another example is Pilobolus, a fungus which grows on animal dung.

Basidomycota

Basidomycota is the second largest phyla of fungi. Basidomycota are filamentous fungi composed of hyphae. This phyla is divided into three classes, which are Pucciniomycotina, Ustilaginomycotina and Agaricomycotina. Basidomycota produce both asexually and sexually. They produce sexually through the formation of special club shaped end cells called basidia, that extend out into four meiospores. They have no recognizable male or female counterparts and the compatible nuclei just migrate into each others mycelia and pair with the resident nuclei there. The Basidomycota that produce asexually do so through yeast stages, which use meiosis.

The giant puffball or Calvatia gigantea can be used as a food. If collected before spores form, while the flesh is still white, it can be cooked in slices fried in butter. It can also be used in some recipes as a substitute for eggplant.

One example is Bloxam’s entoloma.

source- http://www.arkive.org/media/DFD50765-0247-4B3E-8EDF-51E138749DEC/Presentation.Large/photo.jpg

Ascomycota

The Ascomycota fungi are most commonly known as sac fungi and are the largest group of fungi. Most sac fungi grow as a thallus, or twig like formation consisting of many hyphae. The sac fungi produce large amounts of asci, or sacs which bud off the ends of hyphae. Most Sac fungi produce asexually, but some produces sexually. The traits that keep these two groups in the same phyla are that they both contain similar DNA. Most Sac fungi digest dead biomass by sending out enzymes that break organic substances into small molecules. Other sac fungi act as parasites on plants and animals, attacking them and draining nutrients from their cell tissue. Asexual reproduction happens two ways in Sac fungi. One way is that a double dividing wall forms between cells and then the central layer dissolves, releasing spores to the environment. The other way is that the cell wall simply goes away, releasing the spores.

Penicillium chrysogenum is a fungi that was discovered by Alexander Fleming. Penicillium chrysogenum releases penicillin G, which is an antibiotic that kills and prevents the growth of bacteria. This fungi was used as an antibacterial agent and created a new age of antibiotics derived from microorganisms.

An example is cup fungi which is a mushroom that grows in the shape of a cup.

Source- http://library.thinkquest.org/17456/media/orangefungi.jpg

Zygomycota

Zygomycota are the smallest group of fungi. Members of Zygomycota are known for their growth on high sugar containing organisms, such as fruit, and for their rapid growth. They also are found as parasites on some plants and animals. They produce sexually through zygospores, following fusion of the gametes. Some also produce asexually through sporing. This group of fungi is the most diverse and has seven groups within it, all differing greatly in their makeup and their ways of obtaining nutrients.

Some Zygomycotas in the order Mucorales are used in the industrial world during the production of alcohol and citric acid.

An example is C. Dimargaris, which is a microscopic fungi that lives as a parasite on insects.

source- http://comenius.susqu.edu/bi/202/Fungi/zygomycota.htm

Deuteromycota

Deuteromycota is called the imperfect fungi group because they are yet to be fully classified. All members produce asexually by means of conidia. They all possess well-developed mycelia. There are 25,000 species of imperfect fungi.

Cercospora, a species of Deuteromycota, produces enzymes which degrade petroleum products and are used in oil spill clean ups.

An example of an imperfect fungi is Arthrobotrys, which is a nematode trapping fungi.

source-http://www.nikonsmallworld.com/images/gallery1985/fourbythree/17th1985large.jpg