Lecture 19 Fungi Flashcards

1
Q

How are the fungi, slime molds, and water molds grouped together phylogenetically?

A
  • They are grouped together based on 18S rRNA sequence comparisons.
  • Organisms are grouped together based on the molecular phylogeny of their nuclear SSU rRNA genes and the type of mitochondrial cristae present.
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2
Q

What makes a “true” fungi, well.. “true”?

A
  • Eukaryotic
  • Spore-bearing
  • Chemoorganoheterotrophs with absroptive metabolism
  • Reproduce sexually and asexually
  • Belong to kingdom Fungi (Eumycota) within domain Eucarya.
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3
Q

Define mycology.

A

The study of fungi

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4
Q

Define mycologists.

A

Scientists who study fungi

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5
Q

Define mycotoxicology.

A

The study of fungal toxins and their effects.

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6
Q

Define mycoses.

A

Diseases caused by fungi.

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7
Q

Where are fungi mostly found?

A
  • Mostly terrestrial. There are few aquatic species
  • Many are pathogenic in plants or animals
  • Some form associations
    • Mycorrhizae: associations with plant roots
    • Lichens: associations with algae or cyanobacteria
  • They are obligatoryily tied to terrestrial environments.
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8
Q

Define mycorrhizae.

A

Fungi that form associations with plant roots.

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9
Q

Define lichens.

A

Fungi that form associations with algae or cyanobacteria.

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10
Q

What are the beneficial importance of fungi?

A
  • Decomposers
  • Industrial fermentations
    • Fermented foods and beverages
    • Steroids, antibiotics and other drugs
    • Research
      • Model eukaryotic organisms
  • An abundance of our antibiotics come from fungi because they natrually produce (they are in a constant battle with bacteria to claim food sources)
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11
Q

What are the detrimental importances of fungi

A
  • Major cause of plant diseases
  • Cause of many animal, including human, diseases
  • Plants tend to be very very susceptible to fungal infections due to the lack of an immune system.
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12
Q

Define thallus.

[Fungi]

A
  • Body or vegetative structure of a fungus
  • Cell walls usually composed of chitin
    • Polysaccharide consisting of N-acetyl glucosamine residues
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13
Q

List and describe the two body forms fungi can take.

A

Yeasts

  • Unicellular fungi
  • Reproduce asexually, often by budding
  • Reproduce sexually by formation of spores.

Molds

  • Filamentous fungi
    • Hyphae
      • The filaments of a mold
      • May be coenocytic (no cross walls) or have septa (cross walls)
    • Mycelium: bundles or tangled masses of hyphae
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14
Q

Define hyphae.

A

The filaments of a mold. May be coenocytic (no cross walls) or have septa (cross walls).

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15
Q

Define mycelium.

A

Bundles or tangled masses of hyphae.

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16
Q

What is dimorphism?

A
  • Ability to exhibit multiple forms
    • Typical of pathogens
  • Some fungi change from yeast (Y) to mold form (M)
    • YM shift
  • In animals, Y in host and M outside host
  • In plants, M in host and Y outside host

Different fungal forms depending on the organism they are colonizing.

17
Q

Define saprophytes.

[Fungi]

A
  • Fungi that obtain nutrients from dead organic material.
  • Secrete hydrolytic enzymes.
18
Q

Describe the nutrition and metabolism of fungi.

A
  • Vast majority of fungi are saprophytes
  • Chemoorganoheterotrophs
  • Glycogen is their primary storage polysaccharide
  • Most are aerobic
    • Some are facultative anaerobes
    • Obligate anaerobic fungi are found in rumen in cattle
19
Q

Describe the asexual reproduction of fungi.

A
  • Both sexual and asexual forms
  • Asexual reproduction
    • Transverse fission: typical division into daughter cells.
    • Budding
20
Q

Describe the spore formation method of reproduction in fungi.

A
  • Spore formation:
    • Fragmentation via pseudospores (arthrospores)
    • Surrounding by thick cell walls prior to relese (chlamydospores)
    • May form within sacks (sporangiospores)
    • Produced at the tips of hyphae (conidiospores)
    • Produced from a vegetative mother cell by budding (blastospores)
21
Q

Describe the sexual reproduction method of fungi.

A
  • Involves union of compatible nuclei followed by formation of sexual spores
  • May be self fertilizing
  • Often has a dikaryotic stage with 2 haploids after cytoplasmic fusion.
  • Zygote formation:
    • Several mechanims
      • Fusion of gametes
      • Fusion of gametangia: gamete-producing bodies
      • Fusion of hyphae
  • Spores often very small for easy dispersal
    • Very resistant to environmental degradation
22
Q

List the characteristics of Division Zygomycota.

A
  • Zygomycetes
  • Form coenocytic hyphae containing numerous hapoid nuclei
  • Most are saprophytes
    • A few are plant and animal parasites
  • Some of industrial imrpotance
    • Foods (Rhizopus), antibiotics and other drugs, meat tenderizer, and food coloring.
23
Q

List the characteristics of Division Ascomycota.

A
  • Ascomycetes - sac fungi
    • During sexual reproduction produce ascus containing haploid ascospores.
  • Considerable human impact
    • Food spoilage and plant diseases
    • Edible mushrooms, and food and beverage production
    • Produces LSD!! (ala witch trials)
    • Research
  • Can be filamentous or yeast form
    • Filamentous forms have septate hyphae and asexual reproduction by conidiospores.
  • Includes our friend yeast
    • Most fall within the Ascomycetes due to mode of sexual reproduction
24
Q

List the characteristics of Division Basidiomycota.

A
  • Basidiomycetes - club fungi
    • Includes smuts, jelly fungi, puffballs, etc.
  • During sexual reproduction form basidium.
  • Human impact
    • Decomposers
    • Edible mushrooms
    • Pathogens of humans, other animals, and plants
25
Q

List the characteristics of Division Deuteromycota.

A
  • Deuteromycetes - Fungi Imperfecti
    • No known sexual reproduction
    • Mostly a JUNK TAXON; when sex is evidenced usually move to a new Division.
  • Most are terrestrial; a few are aquatic
  • Most are saprophytes or plant parasites
    • Some parasitic on other fungi
    • Some predatory
  • Human impact:
    • Some human pathogens (ringworm, athlete’s foot, histoplasmosis)
    • Production of antibiotics (e.g. penicillin), foods (Roquefort cheese), and organic acids (e.g. citric acid)
26
Q

List the characteristics of Division Chytridiomycota.

A
  • AKA the chytrids
  • The simplest of the fungi
  • Microscopic fungi that take different forms
    • Single celled
    • Multinucleate mass
    • True mycelium
  • Reproduce asexually by form of flagellated zoospore
  • Sexual reproduction often involves formation of resting spore or sporangium
  • Terrestrial or aquatic
    • Some saprophytic
    • Some parasites of algae, other fungi, and plants
      *
27
Q

What are slime molds and water molds?

A

Have some resemblance to fungi. Alas, are phylogenetically distinct…

28
Q

List the characteristics of Division Mycomycota (slime molds)

A
  • AKA acellular slime molds
  • Plasmodial slime molds
  • During portion of life cycle exist as plasmodium
    • Multinucleated protoplasm
    • Lacks cell wall
    • Exhibits amoeboid movement

Unlike other fungi that come together and form an aggregate, these guys arise from the single zygote. These guys tend to want to reproduce with someone else.

29
Q

List the characteristics of Divison Acrasiomycota.

A
  • AKA Cellular Slime molds
  • Exist as individual feeding myxamoebae
  • Under certain codnitions aggregate to form a pseudoplasmodium
  • Eventualy sorus (sorocarp) is formed
    • A mature fruiting body
30
Q

List the characteristics of Division Oomycota.

A
  • AKA oomycetes or water molds
  • Filamentous like fungi
    • Cellulose in cell walls rather than chitin
    • Tubular mitochondrial cristae rather than lamellar cristae
  • Usually saprophytic in freshwater habitats
    • Important decomposers
    • Some parasitic on plants and fish
  • Reproduce sexually
    • Form large egg cell, which is fertilized by small sperm cell or smaller antheridium
    • Zygote germinates to form asexual, flagellated zoospores.