Most fungi are a mass of intertwined filaments known as hyphae that are surrounded by a rigid cell wall. Each hypha cell has a distinct nucleus. Individual cells may be separated by walls called septa. The hyphae form a radially expanding network called the mycelium. Cytoplasm flows freely throughout hyphae, passing through major pores present in the septa. Because of this streaming, proteins synthesized throughout the hyphae may be carried to their tips, which are actively growing. As a result, fungal hyphae may grow very rapidly when food and water are abundant and the temperature is optimum.
Which organelle is absent in fungi?
Fungi: Centrioles, which divide and organize the spindle filters during mitosis and meiosis, are lacking in all fungi. The nuclear envelope does not break down and reform; instead, a spindle apparatus is formed within the envelope. Fungi regulate the formation of microtubules during mitosis with small, amorphous structures called spindle plaques.
What main carbohydrate is stored by fungi?
The main carbohydrate stored by fungi is glycogen, which is also the main storage carbohydrate of animals. This fact suggests that fungi are more closely related to ani- mals than plants, which store starch as their main carbohydrate.
What are imperfect fungi?
Imperfect fungi are also called deuteromycetes or conidial fungi. They are an assemblage of distinct fungal species that are known to reproduce only asexually; the sexual reproductive features have not been identified and are not used as the basis for classification. In this group, sexual reproduction has not been observed. Most imperfect fungi are thought to be ascomycetes that have lost the ability to reproduce sexually. The best-known members of the deuteromycetes are the genera Penicillium and Aspergillus. Whenever a mycologist discovers a sexual stage in one of these fungi, the species is reclassified from the imperfect category to a particular phylum; the phylum selected depends on the type of sexual structures.
What is a fruiting body?
Macrofungi such as mushrooms and toadstools produce fruiting bodies. A fruiting body is a structure that enables the dispersal of spores for reproduction. It is the structure of a fungus that is visible above the ground. Fruiting bodies are found in a variety of shapes, ranging from the common cap-and-stem mushrooms to the more exotic, antler-like, coral-like, cage-like, trumpet-shaped, or club-shaped mushrooms. The method of spore dispersal for the various types of macrofungi is related to the shape of the fruiting body.
Are all large fungi shaped like mushrooms?
The fruiting bodies of fungi come in a seemingly endless array of forms and colors. Many are variations on the familiar stalk-and-cap pattern of the common mushrooms sold in stores, although some have minute spore-bearing pores instead of gills on the undersides of their caps. Many fungi do not resemble mushrooms at all. Puffballs are solid, fleshy spheres. Bird’s nest fungi form little cups containing "eggs" packed with spores. One kind of fungus looks like a head of cauliflower, and others resemble upright, branching clumps of coral. Some protrude from tree trunks like shelves, while others look like glistening blobs of jelly.
How do bacterial and fungal spores differ?
The main purpose of bacterial spores (known as endospores) is to protect bacterial cells so they can survive extreme, harsh conditions. Fungi reproduce both sexually and asexually through the formation of spores. Asexual spores are formed by the hyphae of one organism; the organisms that form from these spores are identical to their parents. Sexual spores result from the fusion of nuclei from two strains of the same species of fungus. Organisms from sexual spores derive characteristics from each parent.
What are the main types of asexual spores?
The main types of asexual spores among the fungi are arthrospores, chlamydospores, sporangiospores, and conidia (from the Greek word conidios, meaning "dust"). Conidia and sporangiospores are produced from a fruiting body. Neither arthrospores nor chlamydospores involve a fruiting body. Arthrospores (from the Greek term arthro, meaining "joint") are formed by fragmentation of the hyphae. Chlamydospores are formed along the margin of the hyphae.
They are thick-walled spores. What do spores look like?
Spores vary greatly in size, shape, color, and surface texture. They are generally small. On average, they are usually less than 20 µm, and rarely exceed more than 100 µm— approximately one-tenth the thickness of a dime!