Lecture 17 Fungi

Question 1

what supergroup + subgroup are fungi in?

Answer 1

• Unikonts - Opisthokonts

- more closely related to animals than plants

Question 2

despite their diversity, what are the key traits of fungi? (esp. re: nutrition)

Answer 2

• fungi are chemoheterotrophs that absorb nutreints from outside of their body
• fungi secrete enzymes (exo enzymes) to break down a large variety of complex molecules into smaller organic compounds – external digestion
• versatility of these enzymes - can digest cellulose + lignin from plants; chitin + keratin from animal tissues
• simple organic molecules absorbed by body of fungus

Question 3

what are 6 body structures of fungi?

Answer 3

• most common: multicellular filaments and single cells
• chitin in cell wals
• mycelia
• septae (most) or coenocytic
• large SA:V – morphology good at absorbing nutrients
• grow very quckly

Question 4

what are mycelia?

Answer 4

• branched networks of hyphae adapted for absorption

Question 5

what are septae?

Answer 5

• fungi w/ hyphae divided into cells by septa-cross walls

- pores allow for cell-to-cell movement of organelles

Question 6

what are coenocytic fungi?

Answer 6

• continuous cytoplasmic mass with hundreds or thousands of nuclei

Question 7

what are haustoria?

Answer 7

specialized hyphae in unique fungi that allow to penetrate tissues of their host

Question 8

what are mycorrihizae?

Answer 8

• mutually beneficial relationships between fungi and plant roots
• deliver PO4 ions and minerals to plants
• in most vascular plants

Question 9

what are ectomycorrhizal fungi?

Answer 9

• fungi that form sheaths of hyphae over a root and also grow into extracellular spaces of root cortex
• don’t haustoria

Question 10

what are arbuscular mycorrhizal fungi (endomycorrhizae)?

Answer 10

• extend hyphae through cell walls of root cells and into tubes formed by invagination of root cell membrane

Question 11

how do fungi propagate themselves?

Answer 11

• produce a vast number of spores sexually or asexually

Question 12

why is the spore of fungi different than the spore of plantae?

Answer 12

• made via mitosis AND meiosis (only mei in plants)
• BUT always haploid
• resistant to desiccation and act as dispersal stages

Question 13

what are coenocytic hyphae usually?

Answer 13

homokaryotic – multiple, identical nuclei

Question 14

what are fungal nuclei usually?

Answer 14

haploid, with the exception of transient diploid stages formed during sexual life cylces
- nuclei of hyphae and spores are haploid

Question 15

what does sexual reproduction require?

Answer 15

fusion of hyphae form different mating types - use sexual signalling molecules called pheromones to communicate their mating type

Question 16

what is plasmogamy?

Answer 16

the union of cytoplasm form two parent mycelia

- in most fungi, haploid nuclei don not fuse right away, coexist in mycelium called heterokaryon

Question 17

what is the pairing of two haploid nuclei to a cell, such as a mycelium called?

Answer 17

• dikaryotic

Question 18

what is karyogamy?

Answer 18

nuclear fusion – diploid phase

Question 19

how long is the diploid phase in fungi?

Answer 19

short-lived, undergoes meiosis, producing haploid species

Question 20

how do fungi reproduce asexually?

Answer 20

• molds produce haploid spores by MITOSIS and form visible mycelia
• unicellular yeasts produce asexually by simple cell division –bud cells
• some can grow as yeasts and as filamentous mycelia
• many molds and yeast have no sexual stage known

Question 21

what are the five lineages of fungi?

Answer 21

Phylum:

1. Chytridiomycota
2. Zygomycota
3. Ascomycota
4. Glomeromycota
5. Basidiomycota

Question 22

what are chytridiomychota?

Answer 22

• found in freshwater
• diverged early in fungal evolution, prob PARAPHYLETIC
• have flagellated spores called ZOOSPORES
• cell walls - chitin, use external digestion
• decomposers, parasites, mutualists
• global decline of amphibians - eat their kerating omgalksfjsdka

Question 23

what are zygomycota

Answer 23

• very diverse
• Rhizopus stolonifer hyphae are coenocytic
• named for zygosporangia - site of karyogamy and then meiosis
• resistant to freezing and drying, can survive unfavourable conditions

Question 24

what are glomermycota?

Answer 24

• species forms symbiotic relationships with roots of plants

- form arbuscular mycorrhizae

Question 25

what are ascomycota?

Answer 25

- sac-fungi - larges phylum - separate hyphae - production of sexual spores in sac-like asci contained in fruiting bodies called ascocarps - reproduce asexually by spores called conidia - not formed in sporangia - produced asexually at tips of specialized hypha called conidiophores

Question 26

what are basidiomycota? (club fungi)

Answer 26

- mushrooms, puffballs, shelf fungi, mycorrhizae, plant parasites - decomposers of wood - defined by club like structure called basidium - transient diploid stage in life cycle - long dikaryotic mycelium - reproduces sexually by fruiting bodies called basidiocarps

Question 27

what are characteristics of basidiocarps?

Answer 27

- have thin vertical sheets of tissue called gills that are lined with millions of basidia

Question 28

what are yeasts?

Answer 28

- unicellular fungi that inhabit liquid/moist habitats - asexual rep - occasional sexual rep - asco or basidio

Question 29

what are molds?

Answer 29

- rapidly growing asexually reproducing fungi | - zygo, asco, basidio

Question 30

what are mycorrhizae?

Answer 30

- mutualistic symbiosis of plant roots AND fungi | - glomero, zygo, asco, basidio all involved

Question 31

what are 3 ways fungi interact with organisms

Answer 31

- decomposers - mutualists - pathogens

Question 32

what do fungi do as decomposers?

Answer 32

- break down complex organic compounds to inorganic (mineral) forms - bridge between living and non living world - C + N cycling form dead tissues - Fungi > Bacteria for cellulose & lignin decomp - Fairy Rings - outward growth of decomposer hyphae - mushroom when cond. favourable - release of nutrients form detritus

Question 33

what do fungi do as mutualists?

Answer 33

- plants: mycorrhizae | - animals: digestive services ex Chytrid: guts of sheep and cattle, ants

Question 34

what is a lichen?

Answer 34

- symbiotic association between a photosynthetic microorganism and a fungus - fungi provide enviro for growth, alga provide carbon compounds, cyanobact provide N - fungi of lichens can produce asexually (via soredia)/or sexually

Question 35

what are soredia?

Answer 35

asexual reproduction mechanism of lichen fungi that are small clusters of hyphae with embedded algae

Question 36

what do fungi do as pathogens?

Answer 36

Plants: wilt: hyphae block xylem; necroses: fungi digesting plant tissues Invertebrates: digest chitin, parasites

Question 37

contrast localized subcutaneous vs systemic things?

Answer 37

- LS: infection due to wounds | - systemic: infection widely spread inside host bodies