Fungi (Chapter 31)

Question 1

In general terms, describe the importance of fungal associations with plants.

Answer 1

• live in close association with plants
• Mututalism - x change mycorrhizal associations b/t fungi and plant roods = faster growth of plants supply plants with key nutrients carbon, nitrogen & Phosphorus
• decompose dead wood (absorbe cellulose and lignin) = master recyclers of nutrients in terrestrial environments increasing productivity and bodiversity

Question 2

How are fungi involved in nutrient cycling?

Answer 2

• release nutrients from dead plants and animals key recyclers of carbon, nitrogen, and phosphous
• = increase productivity and biodiversity
• mutualisim - sugars and CO2 for nutrients fro plant

Question 3

What negative impacts do fungi have on the human food supply?

Answer 3

diseases in crop plants fruit spoilage epidemics in trees -> chestnuts and elms

corn smut

saprophitic fungi

Human: diaper rash, ringworm, vaginitis, non bactrial phnemonia

Question 4

Identify Saccharomyces ceriviserae and several common ways humans use it.

Answer 4

bread yeast, beer, wine, cheese, tofu, whiskey

CO2 as a byproduct

Question 5

Fungi are a poorly studied branch of the tree of life with about 80,000 species described. What is one estimate for the actual number of fungal species?

Answer 5

1.65 Million

Question 6

Identify and describe the two common growth forms that occur among the fungi.

Answer 6

• Single-celled forms—yeasts.
• Multicellular, filamentous forms—mycelia.

Question 7

Discuss the characteristics of fungal hyphae and variation in septa.

Answer 7

• filaments that make up a mycelium are called hyphae.
• Each filament is separated into cell-like compartments by cross-walls called septa.
• Gaps in septa called pores enable materials to flow between compartments.

Question 8

Discuss the diversity of reproductive structures in fungi spores

Answer 8

• spores resistant to drying out
• Both the sexually produced gametes
• the asexually produced spores in the chytrids have flagella - only known motile fungal cells.

Question 9

Discuss the diversity of reproductive structures in fungi - swimming gametes

Answer 9

• flagella spores & gametes in wet environments
• only in Chytrids

Question 10

Discuss the Discuss the diversity of reproductive structures in fungi - zygosporangia

Answer 10

The zygomycetes have zygosporangia, formed when cells from two yoked-together haploid hyphae fuse.

Question 11

Discuss the diversity of reproductive structures in fungi d) basidia

Answer 11

Basidia are specialized spore-producing cells that form at the ends of basidiomycetes hyphae.

Question 12

Discuss the diversity of reproductive structures in fungi e) asci

Answer 12

Asci are sac-like spore-producing cells that form at the end of ascomycetes hyphae.

Question 13

Where do fungi appear on the phylogenetic tree of life? What morphological traits link fungi and animals?

Answer 13

1. DNA sequence data.
2. Both animals and fungi synthesize chitin.
3. Chytrid and animal flagella are similar in structure and function.
4. Both groups store glucose as glycogen.

Question 14

Deciphering the phylogeny of the fungi is very much a work in progress. Which fungal groups are monophyletic and which are presently paraphyletic?

Answer 14

• The Chytridiomycota and Zygomycota are paraphyletic. A single common ancestor did not give rise to all species within each phylum.
• The Glomeromycota, a group of zygomycetes, is monophyletic. The Basidiomycota (club fungi) and Ascomycota (sac fungi) are monophyletic, and are the most highly derived groups of fungi.

The two groups are both dikaryotic and together form a monophyletic group.

Question 15

Use experimental evidence to answer the question, “Are mycorrhizal fungi mutualistic?”

Answer 15

Experimental evidence indicates that mycorrhizal fungi and plants are mutualistic.

test via Carbon tagged air ( mychorrhizal in soil vs. without) - carbon moved through plant and was fed to the fungi

in soil tagged Phosphorus and Nitrogen

• went throught the fungi and found in the plant

Question 16

Compare and contrast the two main types of mycorrhizal associations (EMF and AMF/VAM)

Answer 16

• EMF doesn’t enter the root cells Basidiomycota and some ascomycetes, found in temperate regions
• AMF grow into the cells of root tissue and direct contact with the plasma membrane increasing SA found in glomeromycota, tropical habitat

Question 17

Characterize fungal endophytes, and lichens, including possible benefits to the partners in these associations.

Answer 17

Endophytes in some grasses produce compounds that deter herbivores - some commensal releationships - not noticeable effect

above ground

toxic to plant eaters

but prevents plant from reproducting

Question 18

Discuss extracellular digestion in the wood rot fungi including ‘enzymatic combustion’ in the degradation of lignin, as well as the role of cellulases.

Answer 18

Basidiomycetes can completely degrade both lignin and cellulose lignin peroxidase to get to cellulose via cellulases to form glucose

• extracellular digestion
• uncontrolled oxidation by lignin peroxidases - the oxidation of lignin cannot be harness to drive ATM prodution
• denegration of lignin gives access to cellulose and allows lignin peroxidases to expose cellulose
• exposed cellulos degrated by cellulases specifically transform stoage into glucose

Question 19

Fungal reproduction is varied. a) Explain why in the fungi we generally do not see eggs and sperm but instead have mating types.

Answer 19

• Chytridiomycota produce gametes, and no fungus produces gametes that are different enough in size to be called sperm and egg. In many fungi, fertilization occurs in two steps, which can be separated in both time and space:
• Fusion of cells.
• Fusion of nuclei from the fused cells.

Question 20

Fungal reproduction is varied. b) In most fungal groups, instead of fertilization, the concepts of plasmogamy and karyogamy are used instead. Explain.

Answer 20

• sexual reproduction begins when hyphae from two individuals fuse to form a hybrid hypha.
• Plasmogamy occurs when the cytoplasms fuse. If the nuclei remain independent, the mycelium becomes heterokaryotic.
• Karyogamy occurs when the nuclei fuse to form a diploid zygote.

Question 21

How does the life cycle of Chytrids differ from the generalized fungal life cycle?

Answer 21

• Chytridiomycota are the only fungi that produce gametes and exhibit alternation of generations.
• Swimming gametes are produced by mitosis in haploid adults.
• Gametes fuse to form a diploid zygote, which grows into a sporophyte.
• Haploid spores, which disperse by swimming, are produced by meiosis inside the sporophyte’s sporangium.

Question 22

List key features of Microsporidia Examples

Answer 22

• single celled
• parasitic with a polar tube
• reduced genome
• lack mitochondria

Question 23

List key features of Chytrids Example

Answer 23

• not monophyletic aquatic - typically fershwater environment spores with flagellum
• can digest cellulose
• lifestyles range from decomposers to parasites to mutialists

Question 24

List key features of Zygomycetes

Answer 24

• Zygomycota form yoked hyphae that produce a spore-forming structure.
• Soil dwellers
• Plasmogamy forms a zygosporangium that develops a tough, resistant coat. Inside the zygosporangium, nuclei from the mating partners fuse—meaning that karyogamy occurs many sprophytes

Question 25

List key features of Glomeromycota

Answer 25

• AMF are all members of Glomeromycota
• spores develop underground
• difficult to grow in lab
• Very important to grasslands and tropical forests

Question 26

List key features of Basidiomycota

Answer 26

• basidiomycete reproductive structures originate from the heterokaryotic hyphae of mated individuals
• Karyogamy occurs within the basidia.
• The diploid nucleus that results undergoes meiosis, and four haploid spores, which will eventually be ejected and dispersed by the wind,
• mature dikaryotic mycelia food sourses and boiolgical research

Question 27

List key features of Ascomycota

Answer 27

• Ascomycota have reproductive structures, which are produced by dikaryotic hyphae, with many spore-producing asci.
• After karyogamy occurs inside each ascus, meiosis takes place and haploid spores are produced.
• When the ascus matures, the spores inside are forcibly ejected and then dispersed by the wind.
• two major groups: lichen formers and non-lichen formers

Question 28

Which key features match to the appropriate lineage of fungi Have a dikaryotic stage; basidium is the site of meiosis – producing four spores; basidia often borne in large, above ground reproductive structures; some are ectomychorrhizal

Answer 28

2

Question 29

Which key features match to the appropriate lineage of fungi Single-celled intracellular parasites; infection by polar tube which penetrates the membrane of the host cell; highly reduced genome; lack functioning mitochondria

Answer 29

2

Question 30

Which key features match to the appropriate lineage of fungi Have a dikaryotic stage; ascus is the site of meiosis – producing eight ascospores; many are lichen-formers; some prey on microscopic animals and protists

Answer 30

2

Question 31

Which key features match to the appropriate lineage of fungi Common saprophytes and parasites in freshwater and wet soils; flagellated spores and gametes with a single flagellum; mutualists in the guts of ruminant animals

Answer 31

2

Question 32

Which key features match to the appropriate lineage of fungi Hyphae of differing mating types fuse to form a zygosporangium where nuclear fusion, then meiosis occurs; common in soil; asexual reproduction extremely common

Answer 32

2

Question 33

Which key features match to the appropriate lineage of fungi

Answer 33

2

Question 34

Which key features match to the appropriate lineage of fungi The only group that form arbuscular mycorrhizae (AMF); hyphae lack cross walls; produce large underground asexual spores; no sex evident

Answer 34

2

Question 35

Which class of taxa of do these fungi belong? Cup fungi, truffles, lichens, morels, yeasts (ex. Saccharomyces, Candida); Penicillium; nematophagus fungus Dreschslerella

Answer 35

Ascomycota

Question 36

Which class of taxa of do these fungi belong? Arbuscular mycorrhizal fungi Glomus, Gigaspora

Answer 36

2

Question 37

Which class of taxa of do these fungi belong? Mushrooms (ex. Agaricus), boletes, brackets, earthstars, puffballs, stinkhorns, bird-nest fungi, coral fungi, rusts, smuts

Answer 37

Basidiomycota

Question 38

Which class of taxa of do these fungi belong? Include common moulds Rhizopus, Mucor; coprophilic fungi Pilobolus, Spiromyces

Answer 38

2

Question 39

Which class of taxa of do these fungi belong? Parasites of insects and vertebrates, Nosema tractabile

Answer 39

2

Question 40

Which class of taxa of do these fungi belong? Batrachochytrium causes chytridiomycosis in amphibians; Spizellomyces are anaerobic gut fungi in ruminants

Answer 40

2

Question 41

uh oh

Answer 41

Fungi secrete enzymes so that digestion takes place outside their cells. Their morphology provides a large amount of surface area for efficient absorption.

Question 42

____________ occurs when the nuclei fuse to form a diploid zygote.

Answer 42

Karyogamy

Question 43

sexual reproduction begins when hyphae from two individuals fuse to form a hybrid hypha. ____________ occurs when the cytoplasms fuse.

Answer 43

Plasmogamy

Question 44

Many lichens reproduce asexually via the production of small “mini-lichen” structures called _________ that contain both symbionts

Answer 44

soredia