24.1 Characteristics of Fungi

Question 1

Cell structure & Function

Answer 1

• Eukaryotic (with some having structures similar to plastids)
• Pigmented (to protect from U.V)
• Thick chitin & glucan cell wall (polysaccharides)
• Ergosterol and NOT cholesterol in the cell membrane
• Mostly non-motile

Question 2

Fungal growth

Answer 2

• Vegetative body is a thallus (can be multi or unicellular)
• Dimorphic fungi can shift between multi-uni cellular depending on the enviornment
• most unicellular fungi are yeasts

Question 2

Morphological states

Answer 2

Vegetative (nutrition and growth) & Reproductive

Question 3

Vegetative state

Answer 3

• slender thread-like hypha(e)
• the mass of all hyphae is the mycelium
• they can grow in soil, decay, liquid, living tissue or any surface.

Question 4

Hyphae structure

Answer 4

• divided by “endwalls” known as septa or septum

Question 5

Perforated septa

Answer 5

holes in the septa, most phyla have these.

Question 6

Coenocytic hyphae

Answer 6

large multinucleated cells without septa (not preffered by evolution)

Question 7

Optimal Growth Enviornment

Answer 7

• Slightly acidic
• Moist
• Light (optional)

Fungi can be either
Obligate aerobes
Obligate anaerobes
Facualtice anaerobes (such as yeast)

Question 8

Fungal Nutrition

Answer 8

Saprobes (Heterortophic) for dead/decomposing matter
- no carbon or nitrogen fixing, only consumption
- digestion before ingestion

Question 9

Fungal Digestion

Answer 9

• Exoenzymes secreted by hyphae
• Nutrients absorbed by mycelium

STORED AS GYLCOGEN NOT STARCH
- way of breakdown and nutrition uptake can be used in bioremediation (diesel oil, PAH, heavy metal uptake)

Question 10

Parasitic fungi

Answer 10

Have specialized hyphae = Haustoria
- it penetrates tissue of the body and absorbs or releases digestive enzymes

Question 11

Types of reproduction of fungi

Answer 11

Perfect fungi = Asexual and sexual
Imperfect fungi = Asexual
- both produce & disperse spores

Question 12

Asexual reproduction

Answer 12

1) Budding
2) Producing spores
3) Fragmentation

Question 13

Budding

Answer 13

Asexual
-> mitosis adjecent (no even split cytokinesis)

Question 14

Producing spores

Answer 14

Asexual
-> Mitotis by one parent /genetically identical to them
-> spores are released from the thallus either outside or from the sporangium

Question 15

Sporangium

Answer 15

reproductive sac

Question 16

Types of asexual spores

Answer 16

Conidiospores => directly from tip of hypae
Sporangiospores => from sporangium
- spores can also bud or fragment off the thallus

Question 17

Sexual Reproduction

Answer 17

Homothallic = Both mating types are present in the same mycelium (so it is self-fertile)
or
Heterothallic = 2 different but compativle mycelium are together.
-> sexual reproduction often occurs in response to adverse enviornmental conditions

Question 18

Steps of sexual reproduction

Answer 18

1) plasmogamy (fusion of cytoplasm)
2) karyogamy (fution of 2 haploid nuclei)
3) meiosis (occurs in gametangia organs)
4) dispersal of spore and germination

Question 19

Gametangia organs

Answer 19

• Makes gametes
• Disseminates spores