BIOEE 1780 Lecture Notes - Lecture 13: Abnormal Posturing, Protist, Microorganism
7 May 2018
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Modern fungi evolved from a unicellular protist with a flagellum.
Multicellularity evolved multiple times in eukaryotes.
Opisthokonts: fungi, choanoflagellates, and animals
• These organisms share a common ancestor that isn't shared by other eukaryotes.
• Synapomorphy: the flagellum, if present, is posterior
o Note: the flagella of all other eukaryotes are anterior.
• Most species have lost the flagellum, or it is only present during certain stages of the life cycle
Fungi: unicellular or multicellular; usually found in moist environments
• Synapomorphy: absorptive heterotrophy, chitin
• Very diverse (>100,000 species)
• Chitin: strengthens the cell walls of hyphae
• Absorptive Heterotrophy: digestive enzymes are secreted to break down large food molecules in
the environment, and the products are absorbed through their cell membranes
• Yeasts: unicellular, free-living fungi
o Live in moist/liquid environments
o Absorb nutrients across their cell surfaces
o Reproduce asexually
• Mycelium: the body of a multicellular fungus
o Composed of a mass of tubular filaments called hyphae, which absorb nutrients and exchange
organelles
o Hyphae cell walls are strengthened by chitin.
o Provides fungi with an enormous surface area to volume ratio
• Improves absorptive heterotrophy
• Lose water rapidly in dry environments
• Can grow rapidly in favorable conditions
• Can survive in hypertonic environments
• Can grow in extreme temperatures (low and high)
• Fungal Lifestyles
o Saprobic Fungi: absorb nutrients from dead organic matter
• Secrete enzymes that digest cellulose, lignin, and keratin
• Major decomposers
• Recycle elements (ex. carbon cycle)
o Parasitic Fungi: absorb nutrients from parasitic interactions, with varying dependence on their
host
o Predatory Fungi: can trap and kill prey, such as roundworms
• Use adhesives and a constricting ring to kill prey
o Mutualistic Fungi (ex. lichens)
• Symbiotic Mutualism: two species are in close association and both parties benefit
• Mushrooms: spore-producing fruiting structures
Parasitic Fungi
• Facultative Parasites: can grow on living organisms or live independently
• Obligate Parasites: can grow only on a living host
• Plants and insects are common hosts for parasitic fungi.
Document Summary
Modern fungi evolved from a unicellular protist with a flagellum. These organisms share a common ancestor that isn"t shared by other eukaryotes. Synapomorphy: the flagellum, if present, is posterior: note: the flagella of all other eukaryotes are anterior, most species have lost the flagellum, or it is only present during certain stages of the life cycle. Fungi: unicellular or multicellular; usually found in moist environments: very diverse (>100,000 species, chitin: strengthens the cell walls of hyphae, absorptive heterotrophy: digestive enzymes are secreted to break down large food molecules in. Lose water rapidly in dry environments: can grow rapidly in favorable conditions, can survive in hypertonic environments, can grow in extreme temperatures (low and high) Fungal lifestyles: saprobic fungi: absorb nutrients from dead organic matter. Symbiotic mutualism: two species are in close association and both parties benefit: mushrooms: spore-producing fruiting structures. Parasitic fungi: obligate parasites: can grow only on a living host, plants and insects are common hosts for parasitic fungi.
