11 - Fungal biology*

Question 1

Fungi

Answer 1

Diverse group of eukaryotic organisms that are spore-bearing, have absorptive nutrition, do not photosynthesise, and normally reproduce both sexually and asexually. Vary greatly in size and shape (most fungi underground as hyphae)

Question 2

Structure of fungi cells

Answer 2

Contain nucleus, mitochondria, ER, ribosomes, microfilaments, microtubules, plasma membrane and cell wall

Question 3

Hyphae

Answer 3

• Tubular branching filament
• Can be either:
• Aseptate (coenocytic): protoplasm streams through the hyphae
  OR
• Septate: have a septum with pores to allow streaming

Question 4

Mycelium

Answer 4

• A mass of branching hyphae
• A type of thallus (body or vegetative structure of fungus) - extensionf

Question 5

Mold

Answer 5

Fungi producing filamentous growth

Question 6

Exceptions to characteristics of fungi

Answer 6

• Yeasts are unicellular, bud, and do not have a mycelial stage
• Some pathogenic fungi are dimorphic induced by temp change (mycelial form outside host, yeast form in host)

Question 7

What are hyphal cell walls composed of

Answer 7

• chitin (NAG)
• Glucan (polysaccharide)

Question 8

Heterotrophic nutrition

Answer 8

Use reduced, preformed organic molecules as carbon source

Question 9

Osmotrophic

Answer 9

soluble nutrients are absorbed through the cytoplasmic membrane

Question 10

Saprophytic

Answer 10

derive nutrition from degradation of dead organic matter

Question 11

Example of predatory fungus

Answer 11

Nermatode trapping fungus

Question 12

Production of Spores

Answer 12

• both sexual and asexual spores may be produced
• asexually on mycelium
• sexually following mating

Question 13

Motility

Answer 13

Most non motile (besides Chytridiomycota)
- exist in water or moist areas

Question 14

Life cycle of fungi

Answer 14

Have simple to complex life cycles involving vegetative growth (mycelium) interspersed with asexual and/or sexual reproduction

Question 15

Characteristics of fungi

Answer 15

• Eukaryotic
• Basic units called hypae
• Cell walls composed of chitin and glucan
• Heterotrophic and osmotrophic nutrition
• Produce spores
• Non motile

Question 16

Why are fungi hard to classify

Answer 16

due to having both sexual and asexual reproduction (same fungi has two different names)

Question 17

What are the six major groups (based on molecular analysis)

Answer 17

• Chytridiomycota
• Zygomycota
• Glomeromycota
• Ascomycota
• Basidiomycota
• Microsporidia

Question 18

types of asexual reproduction

Answer 18

• Also called anamorph
• Hyphal growth (vegetative growth)
• Hyphal fragments transplanted or broken from the body of the fungus can continue to grow
• Asexual spore formation
• Budding (yeasts)

Question 19

Types of asexual spore formation

Answer 19

• Sporangiospores (produced in a membrane enclosed structure called a ‘sporangium’)
• Conidiospores (spores born on tips or sides of ‘conidiophores’ – not enclosed in a membrane)

Question 20

types of sexual reproduction

Answer 20

• Also called telomorph
• Motile gametes
• Gametangial contact (Contact between egg and antheridium)
• Fusion of non motile male and female structures
• Fusion of compatable vegetative hyphaa

Question 21

Zygomycota

Answer 21

• Most are saprophytes
• a few are plant and animal parasites
• production of foods (e.g. tempeh), antibiotics and other drugs, meat tenderiser, and yellow food colouring

Question 22

Characteristics of zygomycota

Answer 22

• Form coenocytic hyphae containing numerous haploid nuclei
• Sexual reproduction requires compatible opposite mating types +/- (‘heterothallic’)
  and produces zygosporangium (contains zygospore)
• asexual reproduction is by formation of a sporangium that produces sporangiospores

Question 23

Example of zygomycota

Answer 23

Rhizopus stolonifera (bread mold)

Question 24

Ascomycota

Answer 24

• Cup shape
• Most are saprophytes
• A few are plant and animal pathogens
• Terriestrial and aquatic

Question 25

Characteristics of Ascomycota

Answer 25

- Septate hyphae - Sexual reproduction: heterothallic or homothallic (self fertile), produces ascospores - Asexual reproduction: formation of conidiospores on conidiophores

Question 26

Examples of Ascomycota

Answer 26

Aspergillus spp, yeasts and truffles

Question 27

Basidiomycota

Answer 27

- Most are saprophytes - A few plant and animal pathogens - Primarily terrestrial - includes edible mushrooms - many produce hallucinogenic compounds

Question 28

Characteristics of Basidiomycota

Answer 28

- Usually septate hyphae - Sexual reproduction: heterothallic, produces basidiospores - Asexual reproduction is rare

Question 29

Examples of Basidiomycota

Answer 29

Common mushrooms (club fungi)

Question 30

What are the ecological roles of fungi

Answer 30

- Decomposers - Disease agents - Symbiosis - Products and industry

Question 31

Fungi as decomposers

Answer 31

- Break down complex macromolecules to simple molecules (e.g. cellulose) - Mineralise organic matter, returning important nutrients (e.g. C, N, P) to the environment - Convert organic matter into fungal biomass (which becomes food for other organisms)

Question 32

Disease agents

Answer 32

- Plants - animals and humans (superficial, cutaneous, subcutaneous, systemic infections)

Question 33

Example of systemic fungal disease

Answer 33

Histoplasmosis

Question 34

Example of superficial fungal disease

Answer 34

Black piedra

Question 35

Example of cutaneous fungal disease

Answer 35

Tinea pedis (athlete's foot)

Question 36

Example of subcutaneous fungal disease

Answer 36

Sporothrix schenckii

Question 37

Two examples of symbiosis

Answer 37

- Lichens: association between Ascomycete + alga or cyanobacterium - Mycorrhizae: association between Ascomycete or Basidiomycete + plant

Question 38

Examples of fungus in products and industry

Answer 38

- Foods/beverages (bread, wine, beer, cheeses) - Industrial chemicals (organic acids, alcohols) - Pharmaceuticals e.g. antibiotics (penicillin)