AP Biology, Chapter 31
Fungi

Summary
Introduction

INTRODUCTION TO THE FUNGI
	Introduction
		1. List the characteristics that distinguish fungi from organisms in the other four 
		kingdoms.
			a. Nutritional mode
				i. Heterotrophs
				ii. Absorption after extracellular digestion
			b. Structural organization
				i. Many filamentous hyphae make up a mycelium
				ii. Nuclei may be separated by septa
				iii. Hyphae may be modified as haustoria for parasitism
			c. Growth: mainly by elongation of hyphae
			d. Reproduction
				i. Asexual by spores or fragmentation
				ii. Sexual by hyphal, followed by nuclear fusion
	Absorptive nutrition enables fungi to live as decomposers and symbionts
		2. Explain how fungi acquire their nutrients.
			a. Secrete exoenzymes for extracellular digestion
			b. Gain nutrients by absorption
			c. Roles: decomposers, parasites, mutualists
	Extensive surface area and rapid growth adapt fungi for absorptive nutrition
		3. Explain how non-motile fungi seek new food sources and how they disperse.
			a. Motile: spores and unicellular forms spread by wind, water, animals
			b. Non-motile
				i. Hyphae grow chemotatically
				ii. Fragments can be spread passively
		4. Describe the basic body plan of a fungus.
			a. Non-clade body plans: yeast, mold, lichen, mycorrhizae
			b. Most common form
				i. Hyphae, branched to form a mycelium
				ii. Tubes of cytoplasm with chitin cell walls and eukaryotic parts
				iii. May or may not (coenocytic) be divided into cells by septa
				iv. Haustoria have tips adapted for penetration
			c. Adaptations
				i. Many thin hyphae provide surface area for absorption
				ii. Each hypha can extend and branch to exploit a new resource
	Fungi reproduce by releasing spores that are produced either sexually or asexually
		5. Describe the processes of plasmogamy and karyogamy.
			a. Plasmogamy
				i. Fusion of cytoplasms
				ii. Dikaryotic (heterokaryotic) hyphae contain two types of haploid nuclei
			b. Karyogamy
				i. Fusion of nuclei
				ii. Pairs of nuclei in dikaryotic hyphae may fuse
				iii. Meiosis may then produce haploid spores

DIVERSITY OF FUNGI
	Introduction
		6a. What defines the clade including all fungi?
			a. Protein and nucleic acid sequence data
		6. Distinguish among the groups Chytridiomycota, Zygomycota, Ascomycota, and 
		Basidiomycota. Include a description of the sexual structure that characterizes each 
		group and list some common examples of each.
	Division Chrytidiomycota: Chrytids may provide clues about fungal origins
			a. General description
				i. Coenocytic hyphae with chitin cell walls
				ii. Mainly aquatic saprobes and parasites
			b. Sexual structure
				i. Only fungus with a flagellated zoospore
				ii. Evolutionary link between fungi and a flagellated protist 
	Division Zygomycota: Zygote fungi form resistant dikaryotic structures during sexual 
	reproduction
			a. General description
				i. Coenocytic hyphae
				ii. Saprophytic and mutualistic as mycorrhizae
			b. Sexual structure
				i. Resistant, dark zygosporangia form at the site of hyphal fusion
				ii. Under favorable conditions: karyogamymeiosisspore formation
				iii. See diagram of characteristic sexual structure in text
			c. Common examples
				i. Black bread mold, Rhizopus
				ii. Cow dung "shotgun" fungus, Pilobolus
	Division Ascomycota: Sac fungi produce sexual spores in saclike asci
			a. General description
				i. Sac fungi
				ii. Hyphae with septa
				iii. Marine, freshwater and terrestrial
			b. Sexual structure
				i. Antheridium of the male hypha transfers its nuclei to ascogonium of 
				the female
				ii. Ascogonium develops into mushroom-like ascocarp
				iii. Karyogamy occurs in hyphal tips
				iv. Meiosis produces haploid spores in saclike asci
				v. See diagram of characteristic sexual structure in text
			c. Common examples
				i. About half are in lichens
				ii. Morels are mycorrhizae
				iii. Truffles cost $600/lb.
				iv. Saccharomyces ferments bread and wine
				v. Rice blast fungus
				vi. Candida
	Division Bascidiomycota: Club fungi have long-lived dikaryotic mycelia and a 
	transient diploid stage
			a. General description
				i. Club fungi: mushrooms, shelf fungus, puffballs, rusts and smuts
				ii. Saprophytes, mycorrhizae, parasites
				iii. Especially adept at digesting wood
			b. Sexual structure
				i. Meiosis takes place in diploid, club-shaped basidia under the 
				mushroom cap
				ii. Haploid spores bud from the ends of the basidia
				iii. Entire fruiting structure = basidiocarp
				iv. See diagram of characteristic sexual structure in text
			c. Common examples
				i. Many edible forms and poisonous toadstools and Amanita
				ii. Stinkhorns
				iii. Rhodotorula, pink shower curtain yeast
	Molds, yeasts, lichens, and mycorrhizae represent unique lifestyles that evolved 
	independently in three fungal divisions
		7. Compare the structures and life cycles of molds, yeasts, lichens, and mycorrhizae.
			a. Molds
				i. Common name for mycelial forms
				ii. Fingi Imperfecti 
					.Old non-clade name Deutromycota
					.No sexual stage; incl. carnivores and Penicillium
			b. Yeasts
				i. Unicellular forms; some also have hyphal forms
				ii. Some reproduce by budding
				iii. Saccharomyces, Rhodotorula, Candida
			c. Lichens
				i. Mutualistic fungi and algae
				ii. Fungi provide structure and protection
				iii. Algae provide autotrophy and nitrogen fixation
				iv. Can co-reproduce asexually by soredia
				v. Important pioneer species; dissolves rock, makes soil
				vi. Indicator species of air pollution
			d. Mycorrhizae
				i. Mutualistic roots and fungi
				ii. 95% of plants participate

ECOLOGICAL IMPACTS OF FUNGI
	Introduction
		8. Describe the roles of fungi in ecosystems.
			a. Decomposers break up large dead organisms, release nutrients
			b. Bind soil: prevent erosion and hold water
			c. Diseases control population growth
	Ecosystems depend on fungi as decomposers and symbionts
	Some fungi are pathogens
		9. Explain how fungi can be dangerous and costly to humans.
			a. Human diseases: athlete's foot, Candidiasis, Aspergillosis, Pneumocystis, nail 
			infection, ringworm
			b. Poisonings: aflatoxin, ergot poisoning, toxic black mold
			c. Agricultural diseases: rusts, smut, rice blast
			d. Expensive corrosion
	Many animals, including humans, eat fungi
		10. Explain how fungi are commercially important.
			a. Fermentation in making bread, alcohol
			b. Antibiotics: Penicillium makes penicillin
			c. Flavorings in cheeses
			d. Genetically engineered to make eukaryotic glycoproteins
PHYLOGENETIC RELATIONSHIPS OF FUNGI
	Fungi and animals probably evolved from a common protistan ancestor
		11. Describe the evolutionary relationships between the four fungal groups.
			a. Represent progressive adaptations for reproduction and dispersal on land
			b. See cladogram in text
		12. Describe the nature of the common ancestor of fungi and animals.
			a. Relationship based on molecular evidence
			c. Both from a flagellated protist ancestor