Fungal kingdom and disease

Question 1

Nutrition

Answer 1

Heterotrophs

- specifically osmotrophs

Question 2

Osmotrophs

Answer 2

1. Digest food outside body
2. Secrete hydrolytic enzymes
3. Absorb organic nutrients

Question 3

Fungal lifestyles

Answer 3

Saprophytes
= live off dead matter
Pathogens
Mutualists

Can be more than one, depending on environment

Question 4

Cell wall

Answer 4

Chitin-based polysaccharide cell wall

Question 5

Aerobic or anaerobic?

Answer 5

Usually aerobic

Some yeasts are facultative or obligate anaerobes

Question 6

6 fungal kingdoms

Answer 6

Basidiomycota 
Ascomycota
Glomeromycota
Zygomycota
Chytridmycota
Cryptomycota

Question 7

Basidiomycota

Answer 7

Basidia

= structure that releases spores

Question 8

Ascomycota

Answer 8

Produce an ascus
= sac of 8 ascospores

Ascus develops on ascocarp

Question 9

Glomeromycota

Answer 9

Arbsucules

V large spores

Question 10

Zygomycota

Answer 10

Zygospores
- V resistant spores
Phototropism

Question 11

Chytridmycota

Answer 11

Motile flagellated asexual zoospores

Only motile fungi

Question 12

Cryptomycota

Answer 12

Highly reduced
No chitin in cell wall
Endoparasitic

Question 13

Fungi 1st to colonise land

Answer 13

> Generate soil
Nutrient transport
Nitrogen cycle

Consumed early bacteria + algae

Question 14

Lichen

Answer 14

Oldest example of a symbiosis

• Fungus provides structure/home
• Alga provides energy/sugar via photosynthesis

Colonisers of a new land

Question 15

Mycorrhizal fungi

Answer 15

(Glomeromycota)

Obligate symbionts
Associate w/ 80% of plants
Form highly branched ‘arbuscules’ within plant cells

Provides greater access to nutrients
Improved disease, pest + stress tolerance

Question 16

Ascocarp fruiting body variations

Answer 16

Apothecium
Perithecium
Cleistothecium

Question 17

Ascomycete life cycle

Answer 17

1. Ascogonia + antheridia fuse
2. Ascocarp with dikaryotic hyphae forms
3. Dikaryotic ascus -> into diploid ascus
4. Meiosis
   = 4 ascospores
5. Mitosis
   = 8 genetically distinct ascospores

Question 18

Basidiomycete morphology

Answer 18

Club fungi

Gills covered in basidia
which produce spores

Question 19

Basidiomycete life cycle

Answer 19

1. • and - hyphae fuse
     = eukaryotic mycelium
2. basidiocarp (fruiting body) forms
3. gills lined with basidia produce genetically distinct basidiospores
4. spores develop into + and - haploid mycelia

Question 20

Which factors contributed to the rise of mammals?

Answer 20

Fungal bloom at end of Cretaceous

Large reptiles susceptible to ecosystem disruption

Small mammals resistant to fungal disease

Question 21

Types of fungal pathogens

Answer 21

Opportunistic pathogens
= cause disease in immunocompromised individuals

Primary pathogens
= causes damage/ disease in healthy individuals

Question 22

When an opportunist becomes a pathogen

Answer 22

Fungi persist in symbiosis with host + bacteria

Disrupting the balance (via mucosal damage, antibiotics + immune defects) promotes fungal outgrowth + disease

Question 23

Candida albicans

= dimorphic

Answer 23

= unicellular yeast that replicates by budding but can switch to hyphal growth

Question 24

Candida albicans

= commensal org

Answer 24

= derives food from another org without harming it

e.g. member of the human microbiome

Question 25

Candida albicans | = obligate diploid

Answer 25

Generates genetic diversity in parasexual cycle Parasex = recombination of genetic material w/out meiosis or zygote formation via fertilisation

Question 26

Candidiasis | = thrush

Answer 26

Normally candida reside on mucous membranes w/out causing infection Switch to hyphal growth promotes disease

Question 27

Invasive candidiasis | = Candidemia

Answer 27

Systemic infection (=affects whole body) Penetrates layers of tissue - > enters bloodstream - > enters organs e.g. lungs

Question 28

Invasive candidiasis | - risk factors

Answer 28

``` Chemo Surgery Low-birthweight Catheters Neutropenia (=low level of neutrophils = type of WBC) ```

Question 29

Candida glabrata

Answer 29

``` V different to C.albicans: > haploid > asexual > doesn't form hyphae > don't know who it causes disease ``` Urinary tract + bloodstream infections

Question 30

Candida parapsilosis

Answer 30

``` >Diploid >Commensal on skin >Cannot form hyphae - exists in yeast/pseudohyphae form >Not obligate human pathogen >Associated w/ biofilm on implants ```

Question 31

Aspergillus fumigatus | = filamentous ascomycete

Answer 31

Food spoilage mould + mycotoxin producer Not a commensal org Optimum growth at 25-40*C - evolved to grow in compost heaps = similar temp to human bodies

Question 32

Aspergillosis

Answer 32

= balls of fungal fibres, blood clots + WBCs in lungs + sinuses caused by Aspergillus Source: abundance of airborne spores from compost heaps + dirty air con

Question 33

Cryptococcus neoformans | = basidiomycete yeast

Answer 33

Unicellular, haploid yeast - replicates by budding Forms polysaccharide capsule Sex + monokaryotic fruiting

Question 34

Cryptococcal meningitis

Answer 34

C. neoformans infection of the brain AIDS-defining illness Cause: airborne basidiospores + dried yeasts

Question 35

Cryptococcus gattii

Answer 35

Lives on trees Infects lungs by inhaling airborne, dried yeast cells or spores Travels via bloodstream

Question 36

Coccidiodes immitis | = primary pathogen

Answer 36

Desert soil dwelling Grows as hyphae - > fragments at ends - > into arthroconidia Dimorphic structures fill with endospores -> when mature, rupture + spread spores

Question 37

Coccidiomycosis | = Valley fever

Answer 37

Caused by Coccidiodes immitis Risk factors: activities associated with dust + airborne dirt Pulmonary + cutaneous

Question 38

Histoplasma capsulatum | = primary pathogen

Answer 38

Dimorphic fungus - in soil, low temp = grows as hyphae - in lungs, high temp = grows as yeast -> budding growth Found in bird + bat faeces

Question 39

Primary vs opportunistic pathogen

Answer 39

Primary = infecting healthy hosts Opportunistic = infecting immunocompromised hosts

Question 40

Life-threatening fungal infections

Answer 40

>2mil each year V high mortality rate

Question 41

Fungal infections commence from...

Answer 41

> Disruption of commensal association | > Acquired by breathing in fungal spores