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MED-109 Biology II ✅ > Topic 7B: Fungi ✅ > Flashcards

Topic 7B: Fungi ✅ Flashcards

(56 cards)

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1
Q

What are fungi?

A

Eukaryotic microorganisms

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2
Q

Fungal types

A

Unicellular: Yeasts (eg Saccharomyces cerevisiae)

Multicellular (eg mushrooms, molds)

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3
Q

Multicellular fungi characteristics

A

Non-motile

Usually live in moist, humid or aquatic environments

Growth temperature: 2-20 degrees

Heterotrophs: absorb nutrients from their external environment

*some are saprophtes (decomposers): obtain their nutrients from dead organic matter

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4
Q

Fungal morphology

A

Cell wall made of chitin

Body structures:
-Multicellular filaments
-Unicellular fungi

Dimorphism: some fungal species (eg Blastomyces) can grow both as filaments or yeasts depending on environmental conditions

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5
Q

Yeasts

A

Unicellular fungi

-usually form multicellular colonies

-reproduce using asexual reproduction (e.g. budding)

Eg Saccharomyces cerevisiae

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6
Q

Multicellular fungi

A

Filamentous structure: consist of mycelia

-filaments = hyphae (Septate, Coenocytic fungi [lack septa])

Mycelia: forma of branched hyphae => aid nutrient absorption and then become sporangia to produce spores

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7
Q

Fungal reproduction overview

A

By either sexual or asexual by producing spores

Asexual:
-simple cell decision (aka binary fission)
-Budding: new organism develops from outgrowth (bud) that separates from parent cell

Sexual reproduction:
-production of diploid zygote (2n) by fusion of haploid (n) fungi (hyphae)

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8
Q

How can haploid (n) sported be produced?

A

Sexually or asexually

Sexual: zygote (2n) —meiosis—> spores (n)
-called sexual spores

Asexual: spore (n) —mitosis—> spores (n)

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9
Q

Germination

A

Under favourable conditions, spores grow back to the vegetative cell (fungal cell)

Spore —germination—> vegetative cell

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10
Q

Fungal life cycle

A

SEXUAL REPRODUCTION
Plasmogamy (cytoplasmic fusion) (n)

-> Heterokaryotic stage (non-fused nuclei from 2 different parents)

-> Karyogamy (nuclear fusion), zygote (2n)

-> Meiosis, spores (n)

-> Germination

Through mycelium

Repeat

ASEXUAL
Through mycelium (n)

-> Spore producing structures

-> Spores

-> Germination
Repeat

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11
Q

Asexual reproduction

A

Yeasts: reproduce mostly asexually by simple cell division and budding

Molds- produce haploid spores by mitosis (e.g. conidia)
-> form mycelia

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12
Q

What are molds and yeasts called?

A

Deuteromycetes

-imperfect fungi

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13
Q

What is the origination of Fungi?

A

Fungi, animals and their protist relative form the Opisthokonts clade (part of the Uniconts Supergroups)

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14
Q
  1. Chytrids
A

Phylum Chytridiomycota

Characterized by zoospores: flagellated spores

Have hyphae

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15
Q
  1. Zygomycetes
A

Phylum Zygomycota

Named after characteristic zygosporangia (e.g. black bread mold)

Spore-producing structures=

-Sporangia: produce spores by asexual

-Zygosporangia:
contain sexually produced spores (by karyogamy and meiosis)
Resist drying and freezing => can survive unfavorable conditions

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16
Q
  1. Glomeromycetes
A

Phylum Glomeromycota

Mychoerrhizae: Mutualistic relationship between fungi and plant roots

Arbuscular mycorrhizal fungi: have specialized hyphae (called haustoria) that pentraate the cell walls of root cells

Mutualistic relationship: mycorrhizae fungi deliver phosphate ions and minerals to plants

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17
Q

What is Arbuscular mycorrhizae formed by?

A

Glomeromycetes

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18
Q

Ascomycetes

A

Phylum Ascomycetes
Sac fungi

Can produce spores by both sexual and asexual

Spore producing structures:

  1. Asci: -produced sexual spores (ascospores)
    -located in ascocarps (fruiting body)
  2. Conidiophores: specialized hyphae that produce asexual spores (conidia)

Eg bread mold Neurospora crasse, Morchella esculenta (tasty morel) and Tuubor melanosporum (truffle)

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19
Q

Fruiting body

A

Multicellular

Reproductive structure

Contains spore-producing structures

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20
Q
  1. Basidiomycetes
A

Phylum Basidiomycota

Club bacteria: characterized by a clublike structure called a basidium (transient diploid stage)

Basidia: spore-producing structures (only produce sexual spores [basidiospores])

Basidiocarp: fruiting body, has numerous basidia)
E.g. mushrooms

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21
Q

Fungi function roles

A
  1. As decomposers:
    -Nutrient recycling between living and non-living
  2. As mutualists:
    -fungi -> animals: in the digestive system
  3. Pathogenic fungi
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22
Q

Pathogenic Fungi

A
  1. Pathogenic Zygomycetes
    E.g. genera Mucor, Rhizopus, Absidia
    - causes skin and ear infections, bronchitis - pneumonia
  2. Pathogenic Ascomycetes
    I: Aspergillus flavus
    -produces mycotoxins such as aflatoxins
    -infects peanuts and wheat
    -Aflatoxin B1: liver cancer (due to p53 mutations)

II: Claviceps purpurea
-infects cereals (eg rye)
-produces ergotamine and lysergique acid (precursors fro LSD synthesis)
-> psychotropic effects (hallucinations, temporary insanity), convulsions, gangrene

  1. Pathogenic Basidiomycetes
    Amanita phalloides: poisonous mushrooms
    -contain lethal toxins (eg phalloidin, amanitin)

Amanita muscaria and Psilocybe cubensis aka magic mushrooms
-psychoactive mushrooms => causes hallucinations (psychotropic effects)

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23
Q

Mycoses

Study These Flashcards
A

Human fungal infections

Major types of human mycoses:

  1. Superficial: Cutaneous mycoses
  2. Subcutaneous mycoses
  3. Systematic mycoses
  4. Opportunistic mycoses
24
Q
  1. Superficial and cutaneous mycoses
Study These Flashcards
A

More common

Fungal infections of hair, nails and skin

-Microsporum furfur: ascomycete that causes ringworm

-Ascomycete genera Trichophyton and Epidermophyton: causes athlete’s foot (ringworm of foot)

25
2. Subcutaneous mycoses
Subcutaneous fungal infection due to trauma -Chromomycosis: caused by the fungi Hormodendrum pedrosoi, Hormodendrum compactum, Phialophora verrucosa -Sporotrichosis: caused by fungus Sporotrichum schenckii -Mycetoma: caused by fungi of the Aspergillus genus
26
3. Systemic mycoses
Fungal infection spread through blood stream to various sites/ organs of the body Commonly cause respiratory infections initially, then spread to other organs -Coccidioidmycosis: caused by Coccidioides immitis -> produces TB-like symptoms -Histoplasmosis: caused by Histoplasma capsulatum -Cryptococcosis: caused by Cryptococcus neoformans -Blastomycosis: caused by Blastomyces dermatitidis -Geotrichosis: caused by Geotrichum candidum
27
4. Opportunistic mycoses
More common Caused by fungi that are part of our normal flora (saliva, skin, digestive system) Normally non-pathogenic Become pathogenic and cause infections only in immunosuppressed individus -yeast Candida albicans: causes candidiasis -> mouth infection (thrush), skin & vaginal infections
28
Industrial and Therapeutic Applications of Fungi
Penicillium chrysogenum: produces penicillin (anti-bacterial anti-biotic) -Penicillium griseofulvum: produces griseofulvin (anti-fungal antibiotic) Production of alcoholic beverages, bread and cheeses Genetic engineering Antibiotic production by fungi: Ascomycetes of genus Penicillium
29
Production of alcoholic beverages, bread and chees
Yeast Saccharomyces cerevisae -production of enzymes used for alcohol fermentation => production of beer, wine etc Also used for baking yeast (CO2 production)
30
Genetic engineering and fungi
Insulin-like growth factor (IGF) can be produced by the fungus Saccharomyces cerevisae Study of genes involved in human diseases
31
Antibiotic production by fungi
Ascomycetes of genus Penicillium The fungus Penicillium chrysogenum produces penicillin which kills Staphylococcus => produces zone of inhibition of Staphylococcus growth around its colonies on nutrient agar
32
Septate
Hyphae type With septa Most fungi have hyphae divided into cells by septa Septa= rings of hyphae cell walls -pores allow cell-to-cell movement of organelles
33
Coenocytic fungi
Aseptate Hyphae type Lack septa Have continuous cytoplasmic mass with hundreds/thousands of nuclei
34
What are fungal nuclei normally?
Haploid Exception: transients diploid stages formed during the sexual life cycles
35
Sexual reproduction of fungi
Fusion of hyphae from different mating types Use sexual signaling molecules (pheromones) to communicate their mating types
36
Plasmogamy
Union of cytoplasm from 2 parent mycelia
37
Heterokaryon
Mycelium in which the haploid nuclei from each parent coexist (don’t fuse right away)
38
Karyogamy
Fusion of haploid nuclei => production of diploid cells
39
What is Penicillium?
Common mold Food decomposer
40
How many species of each type of fungal category are there?
Chytrids: 1,000 Zygomycetes: 1,000 Glomeromycetes: 160 Ascomycetes: 65,000 Basidiomycetes: 30,000
41
Mutualistic relationships examples
Fungi - plants: Mycorrhizae Fungi - animals: in digestive system Fungi - microorganisms: in lichens
42
Lichens
Symbiotic association between a photosynthetic microorganism (cyanobacterium/ green alga) and a fungus (eg an ascomycete) Leaflike = foliose Crustose = encrusting Fruticose = shrublike
43
Pathogenic Ascomycetes
1. Aspergillus flavus 2. Claviceps purpurea 3. Pathogenic Basidiomycetes
44
1. Aspergillus flavus
-produces mycotoxins such as alfaltoxins -infects peanuts and wheat -Aflatoxin B1: liver cancer (due to p53 mutations)
45
2. Claviceps purpurea
-infects cereals (eg rye) -produces ergotamine and lysergique acid (precursors for LSD synthesis) =>psychotropic effects (hallucinations, temporary insanity), convulsions, gangrene
46
3. Pathogenic Basidiomycetes
-Amanita phalloides: poisonous mushrooms -contain lethal toxins (eg phalloidin, amanitin) => alpha-amanitin: inhibits eukaryotic RNA pol II => Phalloidin: inhibits F-actin polymerisation -Amanita muscaria and Psilocybe cubensis: magic mushrooms =>psychoactive mushrooms -> cause hallucinations (psychotropic effects)
47
Mycoses
Human fungal infections
48
Major types of human mycoses
1. Superficial-cutaneous mycoses 2. Subcutaneous mycoses 3. Systemic mycoses 4. Opportunistic mycoses
49
Superficial and cutaneous mycoses
Fungal infections of hair, nails and skin Microsporum furfur: ascomycete, causes ringworm Ascomycete genera Tricophyton and Epidermophyton: causes athlete’s foot (ringworm of foot)
50
Opportunistic mycoses
Caused by fungi that are part of our normal flora (saliva, skin, digestive system) - normally non-pathogenic Become pathogenic and cause infections only in immunosuppressed individuals Eg Candida albicans: yeast, causes candidiasis => mouth infection (thrush), skin infection, vaginal infection etc
51
Industrial and Therapeutic applications of Fungi
Production of antibiotics: eg Ascomycetes of genus Penicillium Production of alcoholic beverages, bread and cheeses: eg the yeast Saccharomyces cerevisiae Genetic engineering: eg insulin-like growth factor (IGF) can be produced in the fungus Saccharomyces cerevisiae
52
Ascomycetes of genus Penicillium
-Penicillium chrysogenum: produces penicillin (anti-bacterial antibiotic) -Penicillium griseopfulvum: produces griseofulvin (anti-fungal antibiotic)
53
Production of alcoholic beverages, bread and cheeses
Eg the yeast Saccharomyces cerevisiae -production of enzymes used for alcohol fermentation =>production of beer, wine etc -also used in baking yeast (CO2 production)
54
Genetic engineering eg
Eg insulin-like growth factor (IGF) can be produced in the fungus Saccharomyces cerevisiae Study of genes involved in human diseases
55
Penicillium chrysogenum
Produces penicillin => kills Staphylococcus =>produces zone of inhibition of Staphylococcus growth around its colonies on nutrient agar
56
Which fungal phylum do mushrooms belong to?
Basidiomycetes

MED-109 Biology II ✅ (9 decks)

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