The Fungi Flashcards
What is one description of the body plan of a fungus.
A fungus may be a unicellular yeast or a filamentous, multicellular mold. The body of most multicellular fungi consists of hyphae that branch and form mycelium.
Describe the distinguishing characteristics of fungi.
Fungi are eukaryotic heterotrophs that secrete digestive enzymes onto their food source and then absorb the predigested food. They also have cell walls that contain chitin.
What is another description of the body plan of a fungus?
In most fungi, perforated septa, or cross walls, divide the hyphae into individual cells. In some fungi, the hyphae are coenocytic, that is, they form an elongated, multicellular cell.
How do fungi reproduce?
Most fungi reproduce sexually & asexually through spores produced on aerial hyphae. The germinate after landing on suitable reproduction spots.
What is plasmogamy?
It is a process that happens when two different mating types of fungi meet and their hyphae fuse, but nuclei remain separate.
What is karyogamy?
It is the fusion of the nuclei between different mating types of fungi.
Describe the life cycle of a typical fungus.
The cytoplasm fuses through plasmogamy, then the fungi enters a dikaryotic stage where new cells has a nucleus of each type. Karyogamy takes place in the hyphal tip and results in a diploid zygote nucleus. Meiosis produces four genetically different haploid nuclei. Each nucleus becomes part of a spore. When they germinate, they form new mycelia by mitosis.
What argument supports that fungi are closely related to animals?
Like animals, some fungi have flagellate cells that propel themselves with a single posterior flagellum. They also have platelike cristae.
What argument supports that chytrids may have been the earliest fungal group to evolve?
Chytrids produce flagellate spores at some stage in their life cycle; the most recent common ancestor of all fungi was a flagellate protist.
What is an example of a chytrid?
A common chytrid is a Allomyces.
List distinguishing characteristics of a chytrid.
Chytrids reproduce both sexually and asexually; their gametes and zoospores are flagellate.
Describe the life cycle of a chytrid.
A Chytrid spends part of its life as a multicellular haploid thallus and part as a multicellular diploid thallus. The haploid thallus produces two types of flagellate gametes that fuse. Both plasmogamy and karyogamy occur, producing a flagellate zygote. The diploid thallus bears zoosporangia that produce diploid zoospores and resting sporangia in which haploid zoospores form by meiosis. The haploid zoospores form new haploid thalli.
What is an example of a zygomycetes?
The black bread mold called Rhizopus or Microsporidia
What are some distinguishing characteristics of a zygomycetes?
Zygomycetes form a haploid thallus that produces both asexual spores and sexual spores.
Describe the life cycle of a zygomycetes?
Asexual spores germinate and form new thalli. In sexual reproduction, hyphae of two different haploid mating types form gametangia. Plasmogamy occurs as the gametangia fuse. Karyogamy occurs, and a diploid zygote is formed; the zygote develops into a zygospore. Meiosis produces recombinant haploid zygospores. When zygospores germinate, each hypha develops a sporangium at its tip. Spores are released and develop into new hyphae.
What is an example of a glomeromycetes?
Because they extend their hyphae into root cells, glomeromycetes are endomycorrhizal fungi, such as the arbuscular mycorrhizae.
List distinguishing characteristics of glomeromycetes.
They have coenocytic hyphae which reproduce asexually with blastospores.
What are examples of ascomycetes?
Yeasts, cup fungi, morels, truffles, and blue-green, pink and brown molds
What are some distinguishing characteristics of ascomycetes?
Some form mycorrhizae; others form lichens. They produce asexual spores called conidia; they produce sexual spores called ascospores in saclike asci.
What is the life cycle of a ascomycetes?
In ascomycetes, haploid mycelia of opposite mating types produce septate hyphae. Plasmogamy occurs, and nuclei are exchanged. A dikaryotic stage occurs in which hyphae form and produce asci and ascocarp. Karyogamy occurs, followed by meiosis. The recombiant nuclei divide by mitosis, producing eight haploid nuclei that develop into ascospores. When the ascospores germinate, they can form new mycelia.
What are examples of basidiomycetes?
Mushrooms, puffballs, bracket fungi, rusts, and smuts
What are distinguishing features of a basidiomycetes?
Basidiomycetes produce basidiospores on the outside of a basidium. Basidia develop on the surface of gills in mushrooms; mushrooms are a type of basidiocarp.
What is the life cycle of a basidiomycetes?
Hyphae in the basidiomycetes have septa. Plasmogamy occurs with the fusion of two hyphae of different mating types. A dikaryotic secondary mycelium forms. Then a basidiocarp develops, and basidia form. Karyogamy occurs, producing a diploid zygote nucelus. Meiosis produces four haploid nuclei that become basidiospores. When basidiospores germinate, they form haploid primary mycelia.
Why are fungi important as decomposers?
Most fungi break down organic compounds in dead organisms, leaves, garbage, and wastes into simpler nutrients that can be recycled.
