Fungus

A fungus (plural: fungi) is a living organism that includes yeasts, molds, mushrooms and others. Fungi have thin thread-like cells called hyphae that absorb nutrients and anchor the fungus in place. Some, such as mushrooms, also have a body containing many cells. Fungi lack chlorophyll to capture energy from sunlight unlike plants. Instead, they derive nourishments by digesting and absorbing dead organic matter around them. The study of fungi is known as  mycology.

The fungi belong to a kingdom of living things, seperated from animals and plants.

The cells of fungi have nuclei, unlike bacterial cells. Hyphae sometimes consist multiple nuclei. Their cell walls are  composed chitin, in contrast to the cellulose found in cell walls of plants. These and other differences show that fungi form a single group of related organisms. This group of fungi is referred to as the Eumycota or Eumycetes. They share a common ancestor, making them a monophyletic group. 

Fungi are saprophytic: a fungus breaks down dead organic matter around it and utilizes it as a source of food. It absorbs the food molecules through its cell wall.p107 Some fungi are parasitic or engage in symbiotic relationships.

Fungi reproduce both sexual and asexual means  in several ways. Many fungi produces spores that develop into new fungi.

Fungi came into existence approximately 1 billion years ago.Fossils from the Devonian period, contains evidence of fungi indicating they likely have an even old history. They scarcity in older fossils due to their rapid decay.

Structure

Reproduction 
Fungi reproduce both sexually and asexually. Some fungi give rise tomushrooms: which serves as fruiting bodies.  Under the cap of a mushroom, gills contain spores that disperse, and may eventually develop into new fungi. Alternatively, fungi use a sporangium to produce asexual spores through mitosis, or sexual spores through meiosis. The spores are haploid.

Fungi can exist as single - celled or multicellular organisms. Yeast is an example of a single-celled fungus that reproduces either sexually or asexually. Asexual reproduction occurs by simple budding (binary fission).

Mycelium 

The mycelium constitutes the vegetative (non-reproductive) portion of a fungus. Typically, it exists underground (or within some other substance and is compose of filaments called hyphae (singular: hypha).

Hyphae 
Hyphae resemble threads or tiny roots. The mycelium consists of a mat of hyphae, which the fungus uses to extract nutrients. Each hypha consists of a long cell enclosed within a tube-shaped cell wall that grows from the end.

Hyphae generally form syncytia, implying that their cell walls (septa) are mostly incomplete, and the cell nuclei are not separated from each other, as in typical cells. Specific details may differ among species.

Symbiosis 
Symbiosis denotes living together. Lichens exemplify a symbiosis relationship between a fungus and an alga or bacterium. In this partnership the algal cells live within the fungal tissue. The outcome is a new mat-like life-form which clings to rock and various surfaces. Approximately 20% of all fungi lives as lichen symbiosis.

Another significant kind of symbiosis is mycorrhiza, where a fungus lives inside plant roots. Most trees contain mycorrhizal roots, as do many crop plants. This benefits both the fungus and the plant.

Pathogens 

Some fungi cause crop diseases, while others induce several diseases in humans. Some are extremly poisonous.

Uses 
 Edible fungi are widely consumed as human food. Certain types of cheese require a fungal species. Examples include Blue cheese and Camembert cheese, which owe their unique flavor and texture to the cheese. 
 Some fungi produce psychotropic (mind-altering) substances. Some people use these fungi recreationally due to their psychedelic properties. These psychedelic mushrooms are often referred as magic mushrooms because of their ability to induce hallucinations. Like any drug, their effect are temporary typically lasting for 4 to 6 hours. Due to their mind-altering effects, many countries have prohibited them. However, scientists are also investigating ways to use "magic mushrooms" as medical applications.
 In modern times, certain fungi (for example, penicillin) have served as  a source of antibiotics. These antibiotics are naturally produced by many fungi as a defense mechanism against bacteria.

Related pages 
 Mycorrhiza
 Mould
 Lichen
 Candida

References