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Bio94 > Lecture 14 Fungi > Flashcards

Lecture 14 Fungi Flashcards

1
Q

What are FUNGI

  1. Definition
  2. What are Saphrophytes
  3. how many species/ How many can be found,
A
  1. “master” Decomposers, recyclers, and symbionts (type of heterotroph), Known as mutualist due to their Frequent mutualistic symbiosis
  2. Saprophytes- make their living by decomposing dead plants
  3. 110,000 species have been named and 6,00,000 can be found
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2
Q

Why are fungi important

  1. Why are fungal mutualisms important to plants?
  2. How do animals participate in fungal mutualisms too?
  3. Why else are they important?

Do fungi grow better with plants and vise versa?

A
  1. fungal mutualisms are very important to plants due to their ability to absorb nutrients and protect plants from herbivores
  2. Animals have fungal mutualisms too in our gut and in gardens
  3. nutrient cycling (carbon cycle)

YES!

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3
Q

List of reasons why people should care about fungi (7)

Are they always mutualist?

A
  1. Disease (Foot fungus aka Athletes foot)
  2. Essential for crop growth
  3. Essential for crop spoilage (spoilage of wheat, corn, barley)
  4. Food source
  5. Antibiotics
  6. Various foods
  7. Industrial enzymes

NO! they are not always mutualist

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4
Q

Are plants or animals closer to fungi? What is some evidence? Why are fungal infections harder to treat than bacterial?

A

Fungi are more closely related to animals than land plants:
1. DNA sequencing
2. Both synthesize chitin
3. Both contain flagella
4. Both store glucose as glycogen
5. Fungal infections harder to treat than bacterial due to shared ancestry in cells and molecules and drugs that disrupt fungal physiology damage humans

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5
Q

What are/what are the relationships among the major fungal groups?

(Go from top to bottom, Which are monophyletic, sister groups) (6 total)

A
  1. Singled-celled, parisitic eukaryotes called microsporidians are fungi (not distantly related sister to fungi)
  2. Chytrids and zygomycetes have not seperated greatly on the phylogeny and display polytomy
  3. Glomeromycota is monophyletic
  4. Basdiomycetes are monophyletic (club fungi)
  5. Ascomycetes (sac fungi)
    (Basdiomycota and ascomycota form a monophyletic group )
  6. Animals and chanoflagelltes are fungi sister groups
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6
Q

What are fungi’s 2 growth forms?

Are these species allowed to adopt both forms?

A
  1. Single celled fungi called yeasts
  2. Multicellular, filamentous forms called mycleia
    - filaments are called hyphae divided into septa (cross walls)

YES!

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7
Q

What is the result of mycelia having very thin hyphae?

A

Nutrient absorption very effecient!
- fungi have higher surface area to volume ratio of all multicellular organisms
HOWEVER, Prone to drying out!
- Most abundant in moist environments
- Reproductive spores resistant to drying out
- Spores can endure dry periods and then germinate

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8
Q

The Nature of Fungal mycelium

Are ALL mycelium static or dynamic? Explain?

A

All mycelia is dynamic
- They constantly grow in direction of food sources and die when food is running out
- Body shape can change throughout its life

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9
Q

Reproductive structures of fungi

How is mycelia an adaptation?
Explain the sexual features of fungi

A
  • Mycleia are an adaptation that supports external digesting and absorvative lifestyle of fungi
  • Produce dense, fleshy reproductive structures
  • Many species do not reproduce sexually (important morphological differences)
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10
Q

Coenocytic Hyphae

What are they?

A

Consist of multinucleate cells
- Lack septa!
- Nutrients move rapidly through septa pores or thru coenocytic fungi from uptake in growth areas

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11
Q

Generalized Fungal life cycle

Asexual and sexual

A

Asexual:
1. Mycelium (n) by MITOSIS creates spore producing struture (n)
2. by MITOSIS creates spres (n)
3. by MITOSIS created mycelium (n)
Sexual:
1. 2 Mycleium fuse via their cytoplasm (PLASMOGAMY) to create heterokaryotic mycelium (n+n) which is not diploid
2. undergoes KARYOGAMY (fusion of nuclei) to form zygote (2n)
3. Undergoes MEIOSIS to make spore producing strucutre (n)
4. These makes spores (n) and process repeats

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12
Q

Chytrids Life cycle (Kit-trids)

Is it motile/nonmotile? Is there a heterokaryotic phase?

A
  1. Haploid adults form gametangia which produce male and female swimming gametes
  2. Swimming gametes fuse (plasmogamy and karyogamy) to create zygote (2n)
  3. Zygote grows and undergoes mitosis into a diploid sporophyte
  4. Sporophytes sporangum undergoes Meiosis and haploid spores disperse by swimming

Motile via flagella! No heterokaryotic!

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13
Q

Zygomycetes life cycle

Define Zygosporongia. How can it reproduce assexually?

A
  1. Sexual reproduction starts when hyphae from different mating types fuse
  2. Plasmogamy forms spore forming zygosporangium that develops into tough, resistant coat
  3. Inside the zygosporngaium, nuclei from the mating partners fuse means that karyogamy occurs
  4. Mycelia can also reproduce assexually by making sporongia, which produce haploid spores by mitosis (dispersed by wind)

Zygosporangia: distinctive spore producing structures of zygomycetes

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14
Q

Basdiomycetes/Basidia

What are the sexually reproductive structures produced by basdiomycetes?
Where do basdiomycete reproductive structures originate from?
Basidia
How many spores does each basidium produce?

What are the sexually reproductive structures produced by basdiomycetes?

A

Basidiomycetes:
- Mushrooms are sexually reproductive structures produced by basidiomycetes
- All basidiomycete reproductive structures originate from dikaryotics hyphae of mated individuals
Basidia:
- Club fungi from basidia which are specialized club like cells at the end of hyphae
- each basidium produces 4 spores

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15
Q

Ascomycetes Life cycle/Asci definition

A

Ascomycetes
- Hyphae or specialized structures from different mating types fuse and forms a heterokaryotic cell with many nuclei
- Short dikaryotic hypha with cells containing two nuclei emerges (growts into reproductive structure with asci)
- After karyogamy, meiosis and one round of mitosis result in production of eight haploid spores
- When ascus matures, spores inside are forcibly ejected
Asci:
- Sac fungi form asci which are reproductive sac like cells at the end of hyphae

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16
Q

What themes occur in the diversification of fungi

A
  1. All fungi absorb food from their surroundings (dont photsynthesize)
  2. Evolution of absorbing nutrients from a wide array of food sources
17
Q

Why are fungi and the first land plants closely associated? What are the different types of symbiosis?

A
  1. The first plants in the fossil record are closely associated with fungal fossils as their ability to absorb nutrients from fungi have been crucial
  2. Fungi and land plants have a symbiotic relationship
    Types
    Mutualistic: benefits both
    Parisitic: one species benefits at the expense of the other
    Commensal: One species benefits, other is unaffected
18
Q

Mycorrhizal Fungi- (Definition, types)

What is the mutualism of plants and mycorrhizal fungi?

A

Plants symbioses via roots
- Ectomycorrhizal fungi (EMF) form sheats around roots and penetrate between root cells
Arbuscular mycorrhizal fungi (AMF) contact plasma membranes of root cells

Plants provide carbs. Mycorrhizal fungi supply plants w/ nutrients

19
Q

Ectomycorrhizal Fungi (EMF)

Where are the found? What do they do? What are the symbioses between host plants and EMF?

Where are they found,

A

-Found on many tree species in different temperature regions
-Form a dense network of hyphae that cover plant roots and extend into the soil but do not enter root cells
- hyphae penetrate decaying material and release peptidases (which cleave proteins, releasing amino acids that the hyphae transport to spaces between plant root cells)
- EMF also provide phosphate ions to the host plant and in return EMF recieve sugars

20
Q

Arbuscular Mycorrhizal Fungi

What do they do? How are they an adaptation? What do its hyphae form?

A

-Hyphae grow into the cells of root tissue (also grow inside root cell walls)
- Hyphae inside plant cell wall are an adaptation that increases surface area for exchange of molecules between fungus and host
- Hyphae form a pipeline from inside plant roots into the soil beyond the root

21
Q

Endophytes

What are the called? Where do they live? When were they found and what do they do?

A

“Inside plants”
- Organisms that live between and within plant cells
- Live in close association with roots or aboveground tissues of land plants
- Unknown before 1940’s but extremely common and highly diverse (increase drought tolerance, produce compounds that benefit plants by deterring or killing herbivores, absorb sugars)

22
Q

What adaptations make fungi such effective decomposers

A
  1. Given enough time, fungi can turn even the hardest, most massive trees into soft soils
  2. Large surface area of a mycelium makes nutrient absorption exceptionally efficient
  3. Saprophytic fungi can grow toward the dead tissues that supply their food
23
Q

Extracellular digestion

What is it? Where does digestion take place? What is the result of enzymation? Why is it important in terms of what it eats?

A

Fungi must digest their food before they absorb it (extracellular digestion)
- Digestion that takes place outside organisms
- Simple compounds resulting from enzymation action are absorbed by hyphae
- 2 most abundant organic molecules on Earth are digested by fungi (lingin and cellulose)

24
Q

Saphrophytes

Definition
How does it help carbon cycle
How does it speed up the carbon cycle

A

-Fungi that digest plant materials
-help cycle carbons through terrestrial systems (thru fixation of carbon by land plants and release of CO2 via cellular respiration)
- For many carbon atoms, saprophytic fungi connect the two components of fixation and release
- Fungi speed up the carbon cycle as they break down dead trees in terrestrial ecosystem

25
Q

Lingin/Cellulose Degradation

A

Lingin Degradation: Saprophytic fungi use lingin peroxidase to break down lingin and expose cellulose that can fuel growth and reproduction (fungi cant live on lingin alone)
Cellulose degradation: Fungi secrete cellulases into the extracellular environment and convert cellulose into glucose that fungus can absorb and use for food.

Bio94 (24 decks)

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