Chapter 31- Fungi Flashcards
What are Fungi
Eukaryotic, Chemoheterotrophs that absorb (rather than ingest) nutrients
What does chemoheterotrophic mean?
Organisms who use organic forms of carbon as both an energy source and carbon source
How many species of Fungi are there
as many as 1.5 million
Whats the largest organism on earth
A fungus
How much of the worlds biomass is fungi
25%-33%
How much do we depend on fungi
Make up about 1/2 composition on our planet
How do Fungi get food
Secrete enzymes on organic material
-Chemical digestion takes place outside of the fungus
What is a Saprobe/saprophyte
A fungus that digests dead organic material
Fungal cells are diploid or haploid?
Haploid-contain only 1 of each chromosome
What are fungal cell walls made of?
Mannan or Chitin
What are unicellular Fungal called
Yeasts
Mycelial fungi are what?
Multicellular fungi
Mycelial cells are what type/called what
They are elongated, fliamentous in shape; called hyphae
What are the two types of Hyphae
Coenocytic Hyphae-multinucleate hyphae (non septate hyphae)
Septate Hyphae-porous partitions called septa, separate nuclei and organelles
What is the Mycelium
Mass of fungal hyphae in multicellular fungus
-equivalent to fungal body
What are the 3 types of Asexual Reproduction
- ) Unicellular-Budding or Binary Fission
- )Fragmentation-Breaking off into two or more pieces
- )Spore Formation-Occurs at tips of specialized hyphae or within Sporangia
What are the most common means of reproduction among fungi
Spores
How do Asexual Spores Form
1N Spore Mother cells undergo mitotic cell division to produce 2, 1N asexual spores
What are the tips of hyphae called in Fungi Sexual Reproduction
Gametangia (1N)
What do Gametangia do
They are the tips of hyphae in Fungi that fuse with opposite mating types
What is Conjugation?
The process of gametangia growing towards each other and fusing
What is the zygote and what are the 2 types?
The zygote is the product of conjugation
- can immediately be a diploid cell
- can go through a dikaryon (1N + 1N) stage before parental nuclei form a diploid nucleus
How does the Fruiting body in Fungi form?
The diploid or dikaryon zygote undergoes mitosis to produce it.
What are the 7 Fungi phyla?
- ) Microsporidia
- )Blastocladiomycota
- )Neocallismastigamycota
- )Chytridiomycota
- )Glomeromycota
- )Basidiomycota
- )Ascomycota
Are fungi Monophyletic?
Yes
Which phyla are animal parasites?
Microsporidia
Do Microsporidia contain Mitochondria?
No
A few characteristics of Chytridiomycota?
Aquatic, flagellated fungi
Motile zoospores
have been implicated in amphibian die off
Which phylum is not monophyletic?
Zygomycota
What are Zygomycetes?
Common bread molds, a few human pathogens, some plant pathogens, most are saprobes
Which form of reproduction is most common in Zygomycetes?
Asexual-Sporangiophores have asexual 1N sporangia that release 1N spores
Steps of Zygomycete Sexual Reproduction
- Fusion of 1N gametangia at tips of hyphae
- Haploid Nuclei fuse to form dikaryotic zygote nuclei
- Develops into 2N zygosporangium in which zygospore develops
- Meiosis occurs during germination of zygospore and it releases 1N zygospores
What Phyla contains the largest percentage of Fungi?
Ascomycota-75%
What type of fungi are in Phylum Ascomycota
Bread yeasts, common molds, cup fungi, truffles, and morels
What Fungi phylum produces Penicillin?
Ascomycota
What is the Phylum Ascomycota named for?
The ascus- a microscopic, saclike reproductive structure within the fruiting body
What is an ascocarp
The fruiting body of an Ascomycete
What type of Hyphae do Ascomycetes have?
Septate Hyphae
What is Karyogamy
The fusion of 1N (dikaryotic) nuclei after conjugation
What are conidia
Condidia appear in Ascomycetes
- Allow for asexual reproduction
- they are spore like structures formed at the ends of modified hyphae called conidiophores
What Phyla are Yeasts in
They are unicellular ascomycetes
How do Yeasts reprdouce
Asexually by budding
What are Basidiomycetes
Phylum Basidiomycota
- Most familiar fungi-mushrooms, toadstools, shelf fungi
- most are saprobes
What type of Hyphae do Basidiomycetes have
Septate
What is the phylum Basidiomycota named for
The basidium-a club shaped sexual reproductive structure in basidiocarp
-karyogami occurs here to form spore mother cell
How are basidiospores formed
Karyogami occurs within basidium to form 2N mother cell
-Meiosis follows and produces 4 1N products that become basidiospores
What are Mushrooms (basidiocarps) made of
formed entirely of secondary mycelium
-formed from basidiospores after they make a primary mycelium
What is another important role (besides decomposition) that fungi play
they recycle important elements such as carbon, nitrogen, and phosphorous
Obligate vs. Facultative symbiosis
Obligate-essential for fungus survival
Facultative-nonessential
Parasites
Cause harm to hosts without causing disease
What is a Lichen
Symbiotic associations between a fungus and a photosynthetic partner
-cyanobacteria, green algae
What Phyla makes up most of the Lichens
Ascomycota
Benefits of Lichens
Protect their partners from strong light and desiccation
-play role in soil formation from rock
Endophytic Fungi?
Live in intercellular spaces inside plants
- some parasitic, some commensalistic
- some protect their hosts from herbivores by producing toxins
What are Mycorrhizae?
Mutualistic relationships between fungi and plants (with root system)
Found on 90% of all vascular plant roots
Benefits of Mycorrhizae?
Increase soil contact and absorption for plant
What are Ectomycorrhizae
Fungal root partners
- most hosts are forest trees
- Hyphae surround but do not penetrate the root cells
What Phylum is associated with Ectomycorrhizae?
Basidiomycota
What negative effects do Fungi have on plants
They can be parasitic or Pathogenic
-May secrete substances making food carcinogenic, unpalatable, or poisonous
Why are fungul diseases difficult to treat
Because of the close phylogenetic relationship between fungi and animals
4 Positive aspects of Fungi
- ) Decomposition
- )Food source
- )Source of antibiotics
- )Fermentation by yeasts
