Lecture 7- Fucking Mushrooms

Question 1

Examples of fungi and their products

Answer 1

Bread, pizza crust (rising)
Mould on bread
Mushrooms
Beer, wine, spirits (alcohol flavours)

Question 2

Characteristics of all fungi

Answer 2

• heterotrophs
• main body is haploid
• no sexes
• multicellular (except yeast)
• cell wall made of chitin
• external digestion of food
• no males or females, just have +/- gamete types that are the same size

Question 3

Structure of of Multicellular fungi

Answer 3

hypha: main body, haploid. basic unit of fungi
mycellcium: branching mass of hyphae

Question 4

Two kinds of hyphae

Answer 4

One has cell wall divisions. Other one doesn’t. Both have cell walls

1) Septate hyphae
- Have cell wall called septum that separates individual cells
- divide nuclei, have pores that allows nucleus to squeeze through it

2) Coenocytic hypha
- “common cell”
- Doesn’t have septum separating cells
- aseptate
- just nuclei and cytosol

Question 5

Specialized hyphae

Answer 5

most fungi are saprobes: eat dead matter
Some are adapted to kill animals ex: haustoria
haustoria extend itself into cell walls of other organisms like plants, doesn’t surpass membrane.
-associated with roots in land plants

Question 6

Growth in fungi

Answer 6

-digest food externally and then grow into it by cell elongation and cell division

Question 7

General Life Cycle of a Fungi

Answer 7

Most undergo asexual reproduction: mycellium, spore producing structure, spores, germination: hypha grows out of spore

Some undergo sexual reproduction
mycellium, Then two different fungi fuse their cytoplasm called plasmogamy.
After plasmogamy it reaches the HETEROKARYOTIC STAGE: this is where the fungi has two different nuclei in the same cytoplasm that has not yet fused (n+n)
After heterokaryotic stage is karyogamy, when the two individual nuclei fuse together to form a diploid zygote
Zygote then undergoes zygotic meiosis producing haploid spores. Zygote just undergoes meiosis, (doesn’t go off to become some diploid structure)
The spore then germinates: hypha body grows out of it
Then enters asexual life cycle

Question 8

Fungi Spores

Answer 8

-Resistant, last a long time
-single haploid cells (n)
-very small, less than 20 um
-Each contain a nucleus, dehydrated cytoplasm, and protective coat
-Some remain dormant for a long time
Produced by
Asexual reproduction : mitosis
Sexual reproduction: zygotic meiosis

Question 9

Function of spores

Answer 9

Main way how fungi get around:

• Move to a new food source
• avoid or “wait out” bad environment
• sexual reproduction

Question 10

3 types of Asexual reproduction in Fungi

Answer 10

Asexual reproduction can occur in 3 ways:

1) Spores in sporangia: created by the fungal body making spores at tip of hypha
2) Conidia (spores) in Conidiophores: Spores/conidia born on extensions called condiophores. ex: penicillin
3) Budding: only happens in single celled fungi: yeasts
- parent cell buds of daughter cell, has a scar at that point and cannot produce another daughter cell at that point

Question 11

Fungi are closely related to

Answer 11

animals

Question 12

There are ….. phyla of fungi

Answer 12

1) Chytridmycota
2) Zygomycota
3) Glomeromycota
4) Ascomycota
5) Basidiomycota

Question 13

Phylum Chytridmycota

Answer 13

• 1,000 species
• single cells or colonies with hyphae
• single cell has flagellated “zoospore”: haploid and “zoo: because it swims
• Aquatic or soil environment
• Mutualistic decomposers/parasites commensals (benefits itself but doesn’t affect others)

Question 14

Spore release in a chytrid

Answer 14

• converted entire contents of its thallus: flasked-shaped body into flagellated asexual zoospores
• Single cell, made a whole bunch of mitotic divisions of its nucleus
• puts a cell wall around each and releases them all to environment

Question 15

Chytrids are parasites

Answer 15

Responsible for 1/3 amphibian decline

-infects skin

Question 16

Phylym Zygomycota

Answer 16

-1,000 species
-Coenocytic (nonseptate) hyphae
-Decomposes, parasites, commensals
-zygosporangium
ex black bread mould
-produce asexual spores

Question 17

Zygomycota life cycle

Answer 17

1) Mycelium comes out of spore and sends up a stalk. At end of each stalk is sporangium
2) Sporangium produces ASEXUAL spores
3) Occasionally undergoes sexual reproduction, when it does, 2 different fungi fuse cytoplasm through plasmogamy.
4) Plasmogamy produces zygosporangium
5) 2 nuclei fuse in karyogamy (have +/- gamete types) forming diploid nuclei.
6) Diploid nuclei immediately undergo meiosis producing sporangium and spores

Question 18

Phylum glomeromycota

Answer 18

• 160 species
• associated with plant roots that are mutually beneficial, can’t live without them
• non-septate
• called arbuscular mycorrhizae: when they enter plant root, they form a branching structure that is shrub like.
• doesnt break membrane, helps plant cell pick up phosphorous
• in 90% land plants roots

Question 19

Phylum Ascomycota

Answer 19

• “sac” fungi
• 65,000 species
• Unicellular (yeast)
• Multicellular (truffles, cup fungi, morels)
• produces acrospores
• blue cheese (blue spores) and penicillin (asexually reproduced spores)

Question 20

mycorrhizae

Answer 20

association with roots

Question 21

Truffles

Answer 21

• associated with oak roots
• found underground
• ectomycorrhizae

Question 22

Asexual reproduction in ascomycota

Answer 22

unicellular asexual reproduction: budding (yeast)

multicellular asexual reproduction: formation of conidia (spores) on conidiophores

Question 23

Sexual reproduction in ascomycota

Answer 23

makes 8 haploid spores in each ascocarp: “fruiting body”
produces spores called ascospores
fruiting body looks like cup

Question 24

Life cycle of ascomycota

Answer 24

• Asexual reproduction by condo
• spores created at ends of mycelium, clones of parent
• If organism undergoes sexual reproduction: 2 mating types fuse cytoplasm in plasmogamy creating a DIKARYOTIC HYPHAE. 2 nuclei fuse in karyogamy producing diploid nucleus
• Diploid nucleus undergoes meiosis producing 4 haploid cells
• 4 haploid cells undergo mitosis to produce 8 acrospores in the fruiting body

Question 25

Ex of ascomycota: ergot alkaloids

Answer 25

• claviceps purpurea
• several kinds
• turns rye seed/flour into container of spores
• restrict blood flow: gangrenous ergotism
• St.anthonys fire: feel like u are on fire
• Causes hallucinations, believed to cause salem witch trials
• Medical uses
• led to discovery of LSD

Question 26

other examples of ascomycota

Answer 26

boytris: creates crop destructruction, strawberries and wine

Question 27

Budding/Brewer’s/Baker’s yeast

Answer 27

used to raise bread, used in spirits and wine

Question 28

Candida albicans

Answer 28

• normal part of human gut, skin and oral cavity, genital tract
• transmitted from mother to child in birth
• pathogenic
• 2 morphological forms: yeast and hyphae

Question 29

Phylum Basidiomycota

Answer 29

-30,000 species, second biggest division
-fruiting body is basidiocarp (where sexual reproduction occurs)
-mushrooms and puffballs
-decomposes forests and ectomycorrihizal: on the outside of roots
-long lived dikaryotic mycelium (mycelium with two individual nuclei floating around)
-club fungi
ex shittake, amanita
basidium = pedestal

Question 30

Life cycle of a basidiomycete

Answer 30

1) plasmogamy with plus and minus mating type
2) Produces dikaryotic mycelium that reproduces sexually: undergoes karyogamy
3) Diploid nuclei undergo meiosis
ALL HAPPENS IN THE GILLS OF THE MUSHROOM
4) produces 4 products called basidiospore, released from gills

Question 31

Distinguishing features of morphology and life cycles

Answer 31

Chytridiomycota: flagellated zoospores
Zygomycota: resistant zygosporangium as asexual stage
Glomeromycota: form arbuscular mycorrhizae with plants
Ascomycota: Sexual spores (Acrospores) borne internally in sacs called asci, produces a lot of asexual spores (conidia)
Basidiomycota: fruiting body/basidiocarp containing many basidia that produce sexual spores (basidiospores)