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APS 137 Plant Physiology, Reproduction and Growth > Lecture 10: Growth & sexual reproduction > Flashcards

Lecture 10: Growth & sexual reproduction Flashcards

1
Q

spore:

A

small, reproductive structures.

DORMANT

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2
Q

hyphae:

A

long, branching filamentous structure. Main mode of vegetative growth

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3
Q

Mycelium:

A

collective name for mass of hyphae

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4
Q

Mycelium are great of ___, bad for ____

A

great for ABSORPTION

bad for WATER LOSS

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5
Q

fungal diversity is highest in

A

tropics

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6
Q

Germination (Spore –> hyphae) only occurs when conditions are right

A

moisture & nutrients

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7
Q

Hyphae structure:

A

chain of cells:
CONTAINING: golgi, vacuole, lipid body, nucleus, mitochondrion, cell wall, plasma membrane.

CELLS SEPARATED BY SEPTUM

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8
Q

cells in hyphae are surrounded by a

A

tubular cell wall

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9
Q

the major structural polymer in fungal cell walls is typically

A

CHITIN - long chain polymer, v tough

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10
Q

glucans –>

A

really long glucose polymers, crosslink the chitin

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11
Q

4 layers to the fungi cell wall: (INNER TO OUTER)

A
  • Chitin microfibrils & protein
  • Mainly protein
  • The reticulum - glucans and protein
  • outer mixed glucans
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12
Q

FUNCTIONS of the fungi cell wall

A
  • maintain cell shape
  • Barrier to external world (e.g. prevents osmotic lysis)
  • molecular sieve
  • cellular protection (melanised for UV protection)
  • physiology (binding site for enzymes)
  • antigenic properties (regulates interactions with other organisms)
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13
Q

septa are?? (septum)

A
  • divide some fungal cell by internal cross-walls
  • usually perforated by large pores (large enough for organelles to flow between cells) -> movement/ communication between cells
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14
Q

hyphae grow from the

A

TIP

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15
Q

branching:

A

outgrowth a little way behind the tip

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16
Q

hyphae deposition of organelles:

A

at growing tip:

  • mitochondrion more abundant (ENERGY)
  • vesicles adding new section to the cel wall
  • denser cytoplasm in younger plants

further in from tip:

  • storage granule(for lipids, glycogen etc)
  • less dense cytoplasm in older parts
  • vacuole
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17
Q

fungi are heterophiboc/ homophobic?

A

heterotrophic: most acquire external sources of food (like animals)

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18
Q

whats ‘food’ to fungi ?

A

simple sugars, polypeptides and more complex carbohydates.

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19
Q

how do fungi get there food?

A

EXTRACELLULAR DIGESTION

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20
Q

2 types of substances carried in vesicles

A
  • carrying digestive enzymes

- cell-wall components

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21
Q

Extracellular digestion:

A
  • golgi apparatus packages proteins into membrane-bound organelles
  • vesicles carrying precursors are transported to the tip along microtubules & actin filaments
  • vesicles fuse and released digestive enzymes (e.g. amylases, lipase, proteases)
  • resulting organic molecules are taken via plasma membrane proteins
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22
Q

fungal colony structure:

A
  • extension zone
  • productive zone
  • fruiting zone
  • aged zone
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23
Q

extension zone:

A

hyphae are extending into the unexploited medium, seeking out fresh nutrients

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24
Q

productive zone:

A

hyphae linked by anastomososis into a network. Net increase in biomass

25
Q

Anastomosis:

A

fusion between hyphae. Means of communication with itself

26
Q

fruiting zone:

A

Initiation of fruit bodies. Turnover of storage reserves

27
Q

aged zone:

A

Decline phase. Hyphae become vacuolated and empty of protoplasmic contents. Autolysis (self-digestion) occurs

28
Q

indeterminate growth:

A
  • Each ring is a single genototype of Armillaria bulbosa
  • Largest colony found is over 600m in diameter -Growth rate consistently ~ 0.2m per year
  • Age ~ 1500 y
  • Estimate that the fresh weight is at least 10,000kg
  • Communication over large distance maintained by anastomosis
29
Q

a spore germinated to form a

A

hyphae

30
Q

collection of hyphae is called a

A

mycelium (huge SA)

31
Q

hyphae grow at the __ and branch __

A

Hyphae grow at the tip, branch just behind

32
Q

Fungi mating types:

A

are +/- NOT sexes (m/f)

33
Q

do all fungi reproduce sexually?

A

Notallfungireproducesexuallyand many that do are isogamous; thus, the terms “male” and “female” do not apply.

34
Q

isogamy:

A

gametes similar size & structure

35
Q

homothallic species:

A

able to mate with themselves (mate type switching)

36
Q

heterothallic species:

A

only isolates of opposite mating types can mate.

37
Q

4 types of fungi (phylogeny)

A
  • zygomycota (zygomycetes)
  • imperfect fungi
  • Ascomycota (ascomycetes)
  • Basidiomycota (basidiomycetes)
38
Q

2 “higher fungi” (subkingdom Dikarya)

A
  • Ascomycota (ascomycetes)

- Basidiomycota (basidiomycetes)

39
Q

how are the major phyla classified

A
  • mainly on the basis of their sexual reproductive structures
  • also hyphae structure
40
Q

imperfect fungi explanation

A
  • no sexual stage known

- polyphyletic group of species not yet placed in any existing group. 25,000 species

41
Q

non-septate hyphae

A

(aka coenocytic)

  • ZYGOMYCOTA
  • more primitive
  • one cell with many nuclei
42
Q

septate hyphae

A
  • Ascomycota (ascomycetes)
  • Basidiomycota (basidiomycetes)
  • more advanced
  • dividers (septa) between the cells
43
Q

Basidiobycota

-a.k.a Club fungi

A

-Includes these groups: Mushrooms, puffballs, stinkhorns, bracket fungi, jelly fungi ,boletes, chanterelles, earth stars, smuts, bunts, rusts
~31,500 series described

44
Q

Basidium (pl. basidia) are

A

microscopic, spore-producing structure. The presence of basidia is one of the main characteristics of the Basidiomycota

45
Q

each basidium usually bears

A

4 sexual spores (basidiospores)

46
Q

Basidiomycota: Sexual reproduction

A

1.Spores land and germinate. =HAPLOID (n)
2. Hyphal union. Hyphae fuse and PLASMOGAMY occurs =Dikaryotic (n+n)
3. Fruiting body (BASIDIOCARP) develops aboveground. Gills are lined with HYMENIUM (the tissue layer where the cells develop into basidia)
4. KARYOGAMY occurs (fusion of haploid nuclei) in the basidium
= DIPLOID (2n)
5. Meiosis occurs. Basidiospores are formed and released =HAPLOID (n)

47
Q

bioluminescence aids???

A

spore dispersal??

  • prosthetic LED-illuminated acrylic mushrooms can be used to study insect behaviour
  • insects that can disperse fungal spores are attracted to light at night
  • Bioluminesecence peaks at night when it is most visible and thus saves energy
  • Why in tropical forests? Little wind flow
48
Q

plasmogamy:

A

cytoplasm of two parent cells fuses together without the fusion of nuclei

49
Q

Dikaryotic:

A

the two nuclei of two cells pair off and cohabit without fusing (neither truly diploid or haploid) *CONDITION UNIQUE TO THE FUNGI *

50
Q

karyogamy:

A

final step in the process of fusing together two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei

51
Q

Ascomycota a.k.a Sac fungi. includes:

A
  • yeasts, truffles, morrels and Penicillium, also many animal & plant pathogens
  • Largest phylum of fungi (>64000 sp)
52
Q

Ascus (pl. Asci)

A

microscopic, sac-like, sexual structure i which spores are formed; defining feature of the Ascomycota

53
Q

typically how many spores per ascus

A

8

54
Q

Ascomycota: sexual reproduction

A
  • ascospores (n) release (active or passive)
  • formation of GAMETANGIA
  • nuclei migration
  • dikaryotic mycelium (n+n)
  • fruiting body (ascocarp) forms, including HYMENIUM
  • karyogamy occurs (2n)
  • meiosis
  • mitosis (n)
55
Q

Ascomycota: specific mating structure interaction

A

-A very fine hyphae (trichogyne) emerges from one gametangium (ascogonium)
• It merges with a gametangium (antheridium) of the other fungal isolate.
• The nuclei in the antheridium then migrate into the ascogonium

56
Q

HYMENIUM:

A

the tissue layer where the cells develop into asci in the bottom of the cup

57
Q

Zygoymcota a.k.a conjugating fungi.

includes:

A
  • molds, plant symbionts, pathogens to plants and animals (e.g Fly death fungus)
  • Small phylum of fungi (>1050 sp) and most primitive
58
Q

Zygomycota: sexual reproduction

A
  • hypha of two different mating types (+/-) come together
  • Gametangia formed (n)
  • Plasmogamy occurs gives zycosporangium
  • fertilisation (karyogamy)
  • DIPLOID (2n) multinucleate zygospore are within zygosporangium
  • meiosis occurs
  • sporangium forms on top of sporangiophore
  • releases spores AND REPEAT
59
Q

when does dikaryotic stage occur in all fungi

A

between plasmogamy and karyogamy (fertilisation)

APS 137 Plant Physiology, Reproduction and Growth (18 decks)

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