Biological Science 2e

1
A fungus is not a plant.
2
(No Transcript)
3
Multicellular fungi consist of mycelium, which
are made up of strands called hyphae.
Hyphae have enormous surface areas. Absorbs food
from environment. Prone to drying out.
4
Most of body of fungus is feeding
structure. Only reproductive body typically
exposed to air. Thick, fleshy structure of
shroom prevents drying out.
5
Reproductive structure produces spores
6
Ascomycetes have spores in sacs.
Basidiomycetes have spores on clubs.
7
In fungi, cytoplasm of two individuals fuses,
but their nuclei may remain separate for a long
time.
8
Fungal phylogeny is a work in progress! No point
in learning this now, will change.
9
Importance of Fungi 1. Decomposers 2.
Mycorrhizae 3. Lichens 4. Economic Impacts
10
Fungi as decomposers Basidiomycete fungi are the
only organisms that can completely digest the
lignin in wood.
Fungi serve an essential role in the carbon cycle.
11

• Adaptations helping with decomposition
• Extracellular digestion
• Only small molecules can cross plasma membranes.
• Secreted enzymes break down large molecules.

12

• Adaptations helping with decomposition
• Lignin peroxidase
• Enzyme catalyzes removal
• of a single electron creating a
• highly reactive atom.
• Enzymatic combustion
• Uncontrolled oxidation reaction
• breaks up polymer.
• (Most enzymatic reactions very
• specific, but lignin itself highly
• random).
• Randomness of reaction means
• that E from oxidation cant be
• harnessed.

13

• Adaptations helping with decomposition
• Cellulose digestion
• By cutting up lignin, fungi
• gain access to cellulose.
• The cellulase enzymes
• digest cellulose into
• glucose, which can be
• used for food.

14
Importance of Fungi 1. Decomposers 2.
Mycorrhizae 3. Lichens 4. Economic Impacts
15
Fungi as partners with plants Mycorrhizae
Importance of mycorrhizae discovered in
70s. Failure of pine plantations key
observation.
16
Fungi as partners with plants Mycorrhizae
EM fungi on most trees in temperate boreal
forests. Hyphae penetrate dead leaves,
twigs. Release enzymes that cleave peptide
bonds. Provide N to plant in exchange for C.
17
Fungi as partners with plants Mycorrhizae
AMF important in tropics and grasslands, on 80
of plants. Ancient fossil from 400
mya. Provide phosphorus to plant in exchange for
C.
18
(No Transcript)
19
Importance of Fungi 1. Decomposers 2.
Mycorrhizae 3. Lichens 4. Economic Impacts
20
Fungi as colonizers lichens
21
Lichens are composed of fungal hyphae and a
layer of autotrophic green algae or
cyanobacteria Colonize bare rock following
glaciation. First stage in soil building.
22
Importance of Fungi 1. Decomposers 2.
Mycorrhizae 3. Lichens 4. Economic Impacts
23
Of course, the most important economic impacts
are those already mentioned.
24
Fungi rot crops.
25
A fungus called ergot is associated with
accusations of witchcraft.
Ergot poisoning causes convulsions, shaking, or
spasms and sometimes hallucinations or
gangrene. Ergot is the original source from which
LSD first isolated.
http//www.botany.hawaii.edu/faculty/wong/BOT135/L
ECT12.HTM
26
Fungi are thought to contribute to the
worldwide decline of amphibian populations.
27
A fungus has caused the virtual extinction
of the American chestnut. Note the man, to
show scale.
28
The first antibiotic was derived from Penicillium.
This is also the genus used to make blue cheeses.
Penicillium roquefortii is used in the
manufacture of blue cheeses e.g. Roquefort,
Gorgonzola, Stilton, etc. During the fermentation
process the fungus spores are injected into the
curd. By the way, the blue in the blue-cheese is
caused by the pigment in the spores of the
fungus. So, when you eat blue cheese you are
consuming spores by the million. http//www.virtua
lmuseum.ca/Exhibitions/Mushroom/English/Lives/inde
x.html
29
Yeast is the workhorse of eukaryote genetics.
Yeasts are also essential to the production of
wine, beer and bread.
30
Some fungi are just really cool.