BIS 2C Lecture Notes - Lecture 23: Saprotrophic Nutrition, Heterotroph, Choanoflagellate
Fungi in Evolution
Probably evolved from unicellular protist with flagellm
•
Common ancestor of fungi and animals is choanoflagellates
•
Forms clade with animals and choanoflagellates called opisthokont
Fungi have chitin in cell walls and absorptive heterotrophy
○
•
Fungal Structures
Made of hyphae
•
Body is a mycelium - composed of tubular filaments called hyphae
Some have incomplete cross walls called septa/septate
○
Without septa are called coenocytes
○
•
Yeast
Form of free living unicellular fungus
○
Not monophyletic
○
Live in moist environments and can absorb nutrients
○
Easy to culture which makes them model eukaryotic organism
○
•
Pros and cons of hyphae growth form
Pro
High surface area to volume ratio for efficient absorption/ secretion of enzymes on substrate
§
Directly in contact with environment
§
Forage by growth
§
○
Cons
More prone to dry out
§
Difficult to communicate with all cells
§
○
•
Absorptive Heterotrophy
Fungi digest food outside bodies by secreting digestive enzymes to break down large molecules then absorbing
produces
•
Many are saprobes that absorb nutrients from dead organic matter and others are mutualists
•
Importance of Fungi
Fungi are principal decomposers of cellulose lignin and keratin
•
Without fungus carbon cycle would fail and carbon would just be buried
•
Saprobic fungi return carbon to atmosphere
Contribute to decay of organic matter and recycling of elements
○
•
Bacteria do it too but can't penetrate like fungi can
•
Predatory fungi trap microscopic protists
•
Relationships with Fungi
Decomposers
•
Pathogenic fungi
•
Parasitic fungi
Insects and plants most common hosts
○
•
Symbiotic relationships
•
Mutualistic fungi (mycorrhizae)
•
Spore
Dispersal unit of Fungi is spore
Produce huge quantities of spores especially if low on nutrients, spores remain dormant and disperse in new
areas
○
Tiny and easily blown by wind
○
•
Fungi and Humans
Food
Mushrooms, blue cheese, beer
○
•
Toxins
Mycotoxins (Aflatoxin - chicken)
Important in pathogenicity or virulence, secondary impacts on humans or animals
§
Chronic toxicity: associated long term exposure to low threat toxins which might be associated with
higher liver cancer incidence
Asian regions - soy beans- can be affected by aflatoxin
□
§
○
•
Drugs
Penicillin, griesofluvin,
○
Pharmaceuticals
○
•
Decomposition
Wood - cellulose
○
White rot fungi breaks down lignin and cellulose
○
Brown rot fungi breaks down cellulose and bark
○
•
Fungi (23)
Tuesday, February 20, 2018
6:08 PM
Fungi in Evolution
Probably evolved from unicellular protist with flagellm
•
Common ancestor of fungi and animals is choanoflagellates
•
Forms clade with animals and choanoflagellates called opisthokont
Fungi have chitin in cell walls and absorptive heterotrophy
○
•
Fungal Structures
Made of hyphae
•
Body is a mycelium - composed of tubular filaments called hyphae
Some have incomplete cross walls called septa/septate
○
Without septa are called coenocytes
○
•
Yeast
Form of free living unicellular fungus
○
Not monophyletic
○
Live in moist environments and can absorb nutrients
○
Easy to culture which makes them model eukaryotic organism
○
•
Pros and cons of hyphae growth form
Pro
High surface area to volume ratio for efficient absorption/ secretion of enzymes on substrate
§
Directly in contact with environment
§
Forage by growth
§
○
Cons
More prone to dry out
§
Difficult to communicate with all cells
§
○
•
Absorptive Heterotrophy
Fungi digest food outside bodies by secreting digestive enzymes to break down large molecules then absorbing
produces
•
Many are saprobes that absorb nutrients from dead organic matter and others are mutualists
•
Importance of Fungi
Fungi are principal decomposers of cellulose lignin and keratin
•
Without fungus carbon cycle would fail and carbon would just be buried
•
Saprobic fungi return carbon to atmosphere
Contribute to decay of organic matter and recycling of elements
○
•
Bacteria do it too but can't penetrate like fungi can
•
Predatory fungi trap microscopic protists
•
Relationships with Fungi
Decomposers
•
Pathogenic fungi
•
Parasitic fungi
Insects and plants most common hosts
○
•
Symbiotic relationships
•
Mutualistic fungi (mycorrhizae)
•
Spore
Dispersal unit of Fungi is spore
Produce huge quantities of spores especially if low on nutrients, spores remain dormant and disperse in new
areas
○
Tiny and easily blown by wind
○
•
Fungi and Humans
Food
Mushrooms, blue cheese, beer
○
•
Toxins
Mycotoxins (Aflatoxin - chicken)
Important in pathogenicity or virulence, secondary impacts on humans or animals
§
Chronic toxicity: associated long term exposure to low threat toxins which might be associated with
higher liver cancer incidence
Asian regions - soy beans- can be affected by aflatoxin
□
§
○
•
Drugs
Penicillin, griesofluvin,
○
Pharmaceuticals
○
•
Decomposition
Wood - cellulose
○
White rot fungi breaks down lignin and cellulose
○
Brown rot fungi breaks down cellulose and bark
○
•
Fungi (23)
Tuesday, February 20, 2018
6:08 PM