Fungi

Are Chytrids [phylum chytridiomycota] septate or aseptate? Do they have a dikaryon stage?

-Aseptate -Lack Dikaryon stage

What are the key features of Phylum Zygomycota?

-Aseptate EXCEPT when forming gametangia during sexual reproduction -Form sexual Zygosporangium -Form asexual sporangia on zygosphore

-What kind of associations do Phylum Glomeromycota form? -What is needed for their survival -Do they have septa -What kind of reproduction

-Association with plant roots [asbuscular mycorrhizae] -Need host plant to survive -Aseptate -No evidence of sexual reproduction

Where are conidia found? What are the benefits of Conidia?

-At tip of modified hyphae called conidiophore in phylum Ascomycota -Allow ascomycetes to inhabit a new food source quickly

Which ascomycetes are unicellular? How do they reproduce? How are they useful to humans?

-Baker's and Brewer's yeast -Asexually by budding -Ferment carbohydrates, convert glucose to CO2 and Ethanol in absence of oxygen [used for bread, beer, wine]

What makes fungi more closely related to animals than plants?

-Chitin in cell walls is not only found in fungi, but also in the shells of arthropods

Are Basidiomycetes septate? How do they reproduce?

-Septate -Asexually: budding -Sexually: Basidia/Basidospores

What are some shared characteristics among all Fungi that makes them different than other organisms?

-Single celled or multicellular -Cell walls of chitin -Some have Dikaryon stage -Exhibit nuclear mitosis -All heterotrophs -Produce sexually + asexually

Name three different pathogenic Basidiomycetes?

-Wheat rust -Corn smut -Brown rot

When do fungi reproduce asexually? When do they reproduce sexually?

-When conditions are favorable -When conditions are unfavorable and they want to increase genetic diversity to survive

Why are the mushrooms from Genus Amanita [Phylum Basidiomycota] poisonous?

-produce toxins that inhibit RNA Polymerase II + III which are needed for translation

Explain sexual reproduction in Phylum Basidiomycota

1. Begins with Basidiocarp 2. Before Karyogamy, basidium is dikaryotic 3. After Karyogamy, basidium becomes diploid 4. Diploid zygote forms inside of basidium and divides by MEIOSIS to produce FOUR basidiospores on the OUTSIDE of the basidium 5. Basidiospores give rise to Monokaryotic Primary Mycelium 6. During plasmogamy, Mycelium fuse to give become Secondary Mycellium

Name three different types of pathogenic diseases that Ascomycetes are responsible for

1. Chestnut blight [destroys bark] 2. Dutch elm disease: spread by elm bark beetles 3. Powdery mildew: creates powdery coating

Explain steps of Sexual reproduction in Phylum Zygomycota

1. Different hyphae mating types form gametangium containing several haploid nuclei 2. Hyphae of zygomycetes lack septa, except when reproducing sexually 3. Septa forms at base of each gametangium 4. Plasmogamy: cytoplasm of different hyphae fuse, without fusion of nuclei [dikaryotic gametangium] 5. Karyogamy: Haploid nuclei fuse to form diploid zygote 6. Diploid zygote divides by meiosis to produce haploid spores, released by Zygosporangium

Give a very general explanation of sexual reproduction in fungi

1. Haploid hyphae of different mating types fuse 2. Formation of diploid zygote when the haploid nuclei inside of different hyphae fuse 3. In some fungi, zygote forms after dikaryon stage

Explain sexual reproduction in Ascomycetes

1. Hyphae of 2 different mating types form dikaryotic hyphae 2. Dikaryotic hyphae + sterile hyphae =Ascocarp 3. Young ascocarp is dikaryotic and heterokaryotic BEFORE Karyogamy 4. After karyogamy, two haploid nuclei fuse to form diploid zygote 5. Diploid zygote divides by MEIOSIS AND MITOSIS to produce 8 ascospores INSIDE the ascus

What are the three features of fungi mitosis that makes it unique?

1. Nuclear envelope does not break down or reform 2. Spindle apparatus forms within nucleus 3. Spindle plaques take place of centrioles

Explain the formation of mycelium

1. fungal spore comes in contact with food source and germinates, forming a threadlike hyphae 2. Hyphae grows, branching 3. Mycelium is formed

Define mycelium

A mass of connected hyphae that grows through and digests its substrate

What does Phylum Ascomycota include?

Baker's and brewer's yeast, common molds, cup fungi, truffles, morels, penicillin producing fungi

In fungi, spores are what kind of reproduction?

Can be BOTH sexual and asexual

What five fungi are we studying?

Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota

The mature sporophyte of Phylum Chytridiomycota produces what?

Diploid zoospore by mitosis OR Haploid zoospore by meiosis

To what domain and kingdom do Fungi belong?

Domain: Eukarya Kingdom: Fungi

All fungi obtain food and energy from others [heterotrophs], explain the different ways they obtain their food

External digestion: secrete digestive enzyme into food and then absorb digested food Decomposed: feed on dead and decaying wood, leaves, and organic material [break down cellulose + lignin] Parasites: Obtain nutrients at expense of other organisms

Why are Basidiomycetes referred to as Club Fungi?

Form club-shaped sexual reproductive structure called basidium

Explain how fungi play a role in Zombie aunts?

Fungus takes control of their brain, changes their behavior and kills the aunt when the aunt reaches a favorable environment

Explain the difference between Homokaryotic vs Heterokaryotic

Homokaryotic: nuclei are genetically similar to one another Heterokaryotic: nuclei are from genetically different individuals

Since the nuclear envelope does not break down or reform in fungi, what does this cause?

It causes the spindle apparatus to form within the nucleus, moving the chromosomes to opposite poles of the NUCLEUS [instead of the cell, like animals and plants]

What is chitin?

It is a polysaccharide made of glucose molecules that is highly resistant to break down

Where did fungi evolve from?

Living protists

What does the Phylum Basidiomycota include?

Mushrooms, puff balls, jelly fungi, shelf fungi, and mirror yeasts

What is one pathogenic Basidiomycete?

Pathogenic yeast of Genus Cryptococcus, causes severe meningitis in people with HIV/AIDS

Aquatic fungi with flagellated zoospores belong to which phylum?

Phylum Chytridiomycota

Bread molds of the Genus Rhizopus, belong to which phylum?

Phylum Zygomycota

What is the function of the Annulus [Phylum Basidiomycota]?

Protects the gills

Explain septate hyphae in comparison to aseptate hyphae

Septa divide hyphae into individual HAPLOID cells containing one or more nuclei [have pores, allowing exchange of material] Aseptate hyphae form an elongated, multi nucleated giant cell

What kind of reproduction are Phylum Ascomycota capable of? Are they septate?

Sexual: by ascus Asexual: by conidia -Septate

Dikaryon stage is unique to fungi, explain what it means

When the hyphae of two different mating types fuse but the nuclei inside of them have not yet fused [represented by n + n]

Do phylum Zygomycota have a dikaryon stage?

Yes, briefly during plasmogamy when cytoplasms fuse and the nuclei don't. But this stage is followed by Karyogamy [fusion of nuclei]

Before karyogamy, the ascocarp of Ascomycetes is _______________ , __________________

dikaryotic, heterokaryotic

Monokaryotic hyphae can only be _______________, while Dikaryotic hyphae can only be ________________

homokaryotic heterokaryotic

Fungi are composed of long slender filaments called ____________, they can either be _____________ or ___________

hyphae septate Aseptate [coenocytic]

While cytoskeleton consists of microtubules, microfilaments, and intermediate filaments, the spindle apparatus is only composed of ________________

microtubules

Explain the difference between monokaryotic vs dikaryotic

monokaryotic: hyphae has one HAPLOID nucleus per cell Dikaryotic: hyphae has two HAPLOID nuclei per cell