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Lecture 16

BIO SCI 94 Lecture 16: Ch 32 FungiPremium

Biological Sciences
Course Code
Brad Hughes

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Fungi- mostly multicellular eukaryotes
Feeding method-absorb nutrients from living/dead organisms
Feed on dead=most important decomposers
Unique ability-absorb cellulose/lignin that make up wood
Some fungi parasites
Absorb host’s nutrients→ lower host’s fitness
Mutualists-fungi live with other organisms, benefit hosts
Mutualistic fungi colonize roots of land plants
Fungi get sugar from plants→ give plant water/nutrients
Fungi produce toxic compounds→ repel herbivores
Fungi live in guts of insect→ help with digestion
Insects grow fungi→ cultivate/feed on fungi
Fungi-master traders/recyclers
Some release nutrients from dead plants/animals
Some transfer to plants
Recycle/transfer nutrients→ influence productivity/biodiversity
Why Do Biologists Study Fungi?
Some fungi cause horrible diseases in humans/crop plants
Some fungi nourish plants we eat
Fungi important to carbon cycle→ affect climate change
Fungi Have Important Economic Impacts
2000 parasitic fungi species- cause human illness
Includes athlete’s foot, vaginitis, diaper rash, ringworm, pneumonia, thrush
Fungal infections uncommon compared to other illnesses caused by other
Major destructive impact on food supply
Fungi cause fruit/vegetable spoilage
Fungi-rusts, smuts, mildews, wilts, blights-cause billions of dollars of crop
losses each year
Fungi-cause of epidemics
Killed 4 billion chestnut trees
Tens of millions of American Elm Trees
Fungi- many beneficial impacts too
Source of antibiotics, including penicillin
Many cultures eat mushroom
Yeast used to make bread, cheese, soy sauce, tofu, beer, wine, other food
Fungi ferment cacao seeds to make chocolate
Fungi enzymes improve foods like fruit juice, candy,

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Fungi Provide Nutrients for Land Plants
Mycorrhizal association between fungi and plants roots help plant growth
Experiments reveal without fungi plant growth suffers
Plants grow better alongside mycorrhizal fungi
Fungi Accelerate the Carbon Cycle on Land
Saprophytes-fungi digest dead plant material
Carbon cycle- two basic components:
Fixation of carbon by land plants
Release of CO2 from plants, animals, fungi from cellular respiration
Fungi connect two components
Fungi digest lignin/cellulose→ carbon atoms recycle into glucose/CO2
Without fungi, carbon atoms stuck in wood for millennia
How Do Biologists Study Fungi?
110,000 fungi species discovered
Hundreds more found every year
Known species tiny fraction of estimated total of 1.5 millions species
650 fungi species found in guts of 27 species of beetle
Analyzing Morphological Traits
Fung- simple bodies
Two growth forms exist
Single celled forms- yeasts
Multicellular filamentous forms mycelia
Some species have both forms
The Nature of the Fungal Mycelium
Mycelium are dynamic
Grow in food sources, die when food runs out
Hyphae- long, narrow, branching filaments that make up mycelium
Septa- cross walls separating filaments into cells
Pores-gaps in septa, allows materials to flow between compartments
Nutrients move through pores- from regions of uptake to regions of
Some fungi coenocytic-lack septa
Species are single, gigantic, multinucleate cell
Mycelia Have a Large Surface Area
Hyphae thin→ mycelium penetrate tiny fissure in soil→ absorb nutrients plant
roots can’t get
Mycelia made of network of thin hyphae
Fungi-largest area to volume ratio in multicellular organisms
Efficient nutrient/water absorption
Fungi prone to dying out
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