Lecture 21 Flashcards

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1
Q

Where did fungi evolve?

A

-also evolved in water, came out later as they needed something to decompose on land first -almost no fossil record of those= too soft

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2
Q

What is the mushroom we see above the ground?

A

it is just a reproductive structure, most underground

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3
Q

What are fungi often used for?

A

-medicine, antibiotics= attack living tissue as well

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4
Q

What is the structure of a fungi?

A

Fungi are heterotrophic food absorbers, and the vegetative (feeding) structure is a mycelium

  • Mycelium is a network of hyphae: monofilaments (cytoplasm in a tube) with large surface area/volume ratio • Cell walls are chitin microfibrils embedded in a matrix of polysaccharides, protein & lipids
  • Hyphae grow and branch, secrete and absorb, only at their tips.
  • Hyphae may be divided by cross walls called septa. Septa are incomplete, and allow cytoplasmic continuity -only tips grow and absorb= when chitin wall formed nothing gets in not even water -everything happens at the tips -lot of nuclei but not divided into cells= septasemic -septa= incomplete walls -we call it a cell= but not really
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5
Q

How do fungi act as pathogens to plants?

A
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6
Q

How do fungi grow?

A
  • Mycelia are capable of indefinite growth - large biomass!
  • Unicellular yeasts divide by budding
  • because of growing at the tips= indefinite growth
  • largest organisms- fungi 2000 ha large! based on tip growth as long as they have enough food
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7
Q

How do fungi reproduce?

A
  • By non-motile sexual and/or asexual spores (1N),which are long living Otzi boots= 5300 years,very resistent spores, always haploid, have sunscreen against sunlight -spores are everywhere -mushroom circles= usually will be the same mycelium)
  • In fungi, the zygote is the only diploid cell (2N).
• Hyphae can fuse at their tips, forming cells with
 mixed nuclei (heterokaryons).

• Dikaryons (n+n) formed by plasmogamy of
compatible mating types

–sex at the tips, zygote is the only diploid! everything else haploid(exact opposite of humans)

-when two hyphae meet (must be compatible) plus and minus strand at tips=they fuse at the tips= new hyphae with both nuclei = dikaryon and they continue like that and the nuclei don’t fuse till they’re in the mushroom and there fusion= myosis

sometime heterokaryon-more nuclei

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8
Q

What are zygomycota?

A

-phulum of fungi

• Hyphae are coenocytic (no regular septa)

  • Sexual spores are zygospores
  • Zygospores formed by gametangial fusion
  • Meiosis occurs during zygospore germination
  • Asexual spores are sporangiospores
  • e.g. fruit moulds, insect pathogens
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9
Q

List five features defiing the fungi kingdom?

A

• Heterotrophic food absorbers

• Mycelium of haploid hyphae that
grow only at the tips.

  • Walls of chitin
  • Reproduce by non-motile spores
  • Zygote is the only diploid cell
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10
Q

List three features that distinguish the Oomycetes and Fungi?

A
  • oomycetes have walls of cellulose while fungi= chitin
  • oomycete hyphae are diploid and fungal hyphae are haploid
  • oomycetes have flagellated zoospores fungi spores= non motile-thatś why people knew oomycetes were related to brown algae not fungi
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11
Q

How and where do Fungi live?

A

• Heterotrophs

• Secrete enzymes & digest
their food externally, then
absorbed it

• Reserves stored as
glycogen, fats & oils • Wide environmental tolerance

• Produce millions of non- motile spore

-sometimes specific, lot of them will only feed on just one type of thing while other can eat many decomposing things

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12
Q

What are saprophytic Fungi?

A
  • Major recyclers
  • Decompose cellulose, chitin & lignin
  • Environmental tolerance means they grow everywhere other organisms are found
  • major group of fungi
  • break down everything! they don’t usually break down their own chitin though
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13
Q

Whata are the applictaions of fungi?

A
  • Fungi will infect and recycle anything they land on!
  • Fungi can have a role in seed exposure & dispersal in fruits.(some fruits only germinate only if the outer wall of frtuit attacked by fungi)
  • • Suppress competitors using antibiotics and toxins (fungi compete with bacteria= for bodies= or with other fungi)= deadly toxins to prevent the other fungi from eating them
  • the ytry to get their spores far away from their body so they don’t self-fertilize
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14
Q

Are some fungi parasitic?

A
  • yes
  • • Specialised structures & nutrition

• Rusts, blights, wilts and rots of plants

-Parasitic Fungi are everywhere

  • Mycoses and allergies
  • Predators - nematode- trapping fungi

ergot poisoning= (on grains)-the reproductive bit looks like a grain

-basis for LSD, Joan of Ark and salem witches had ergot poisoning= grandiose speeches and so on

–we have a good immune system against fungi, if HIV often die of fungal infections

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15
Q

Who with do fungi form symbiotic associations?

A
  • Mycorrhiza=a symbiotic association between a fungus and the roots of a plant.(fungi forming association with plants -fungi break down bits and feed plant and plant gives ot photosynthetic products)
  • Endophytes
  • Lichens =symbiosis between a fungus and alga (or cyanobacteria)(-alga or cyanobacteria= photosynthetic bit feeding the

-fungi= completely different from animals)

  • Invertebrates
  • Vertebrates
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