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.
