Bio 204 Lecture Final
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- What are the 4 Phyla of Fungi?
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1)Chytridiomycota
2)Zygomycota
3)Ascomycota
4)Basisiomycota - What are some defining characteristics to the Phylum Chytridiomycota?
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-flagellated, motile cells
-predominalntly aquatic group
-only group of fungi with motile reproductive cells (zoospores and gametes)
-most are coenocytic, with few septa at maturity
-parasitic and saprophytic
-several spp are plant pathogens causing minor diseases such as brown spot of corn and crown wart of alfalfa - What are some defining characteristics to the Phylum Zygomycota?
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-form Zygospores in Zygosporangia
-mostly have coenocytic mycelia
-asexual spores are generally formed in sporangia
-zygospores develop within thick walled structures called zygosporangia - What are some defining characteristics to the Phylum Ascomycota?
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-form ascospores internally in Asci
-protoplasts of male and female gametangia fuse, and the female gametangia produce specialezed hyphae that are kikaryotic
-ascus forms near the tip of a dikaryotic hypha
-ascospores are generally forcibly expelled
-asci are incorporated into comple spore producing bodies called ascomata
-typically, asexual reproduction is by formation of usually multinucleate spores known as conidia - What are some defining characteristics to the Phylum Basidiomycota?
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-form basidiospores borne externally on basidia
-include mushrooms, puffvalls, rusts, smuts, etc.
-has basidium (produced at the tip of a kikaryotic hypha and is the structure in which karyogamy and meiosis occur) - What is the most likely ancestor of Fungi?
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-colonial protists
-Chytridiomycota earliest because flagellated - What is a DOLIPORE SEPTUM?
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-the pore of the septum has an inflated doughnut like or barrel shaped margin called a DOLIPORE
-any fungus with a dolipore belongs to the basidiomycota
-on either side of the dolipore may be membranous caps called PARENTHESOMES, because in profile, they resemble a pair of parentheses - Why are Lichens so successful at surviving?
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-due to their ability to dry out very rapidly
-no water = no photosynthesis = slow growth - Is the relationship b/w MYCOBIONT and PHOTOBIONT mutualistic or parasitic?
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-mycobiont parasitizes the photobiont
-mycobiont controls the division rate of the photobiont
-mycobiont provides the photobiont with a suitable physical environment in which to grow and aborbs needed minerals from the air in the form of dust or from rain
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At the lichen level, the relationship is mutualistic - What are MYCORRHIZAE?
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-are intimate and mutually beneficial symbiotic associations between fungi and roots, and they occur in the vast majority of vascular plants, both wild and cultivated
-benefit their host plants by increasing the plants ability to capture water and essential elements (eg: phophorous, zinc, manganese, copper, etc.)
-in return, the fungus gets host plant carbohydrates and vitamins essential for it's growth
-Increase effective surface area for water/mineral absorption
-Secrete growth substances to keep root branches juvenile and absorptive - What are the 2 types of MYCORRHIZAE?
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Endomycorrhizae:
-penetrate root cells
-more common
-penetrate the cortical cells of the plant root, where they form highly branched structures called ARBUSCLES and in some cases, terminal swellings called VESICLES
-most, or perhaps all, exchange between plant and fungus takes place at the arbuscles
Ectomycorrhizae:
-surround root cells, do not penetrate
-extomycorrhizal association makes the trees more resistant to the harsh, cold, dry conditions that occur at the limits of tree growth
-in conifers, the hyphae grow between the cells of the root epidermis and cortex, forming a characteristic highly branched network, the HARTIG NET, which eventually surrounds many of the cortical and epidermal cells
-the hartig net functions as the interface between the fungus and the plant
-in addition to the Hartig net, ectomycorrhizae are characterized by a MANTLE or sheath, of hyphae that covers the root surface
-mycelial strands extend from the mantle into the surrounding soil - What are 4 common features of fungi?
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Absorptive nutrition
-Cell walls
-Extracellular digestion
-Investment before payoff
Modular organization
-Dispersal by fragmentation – short term
-Totipotent cells
Dispersal by spores
-Developmental adaptation
-Long term survival
Chemical warfare
-Toxins associated with sporulation
-Competition to preserve food source - What's the diff between Holobasidia and Heterobasidia?
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Holobasidia
-aseptate
-eg: Coprinus
Heterbasidia
-septate
-eg: Puccinia - What are some advantages of Deuteromycetes?
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-speed (of reproduction, ~1 day)
-flexibility (can maintain a well-adapted genome)
-can maintain (lethal?) mutations in haploid nuclei, since hyphae are multinucleate - What are the roles of sporulation?
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-Dispersal
-Genetic recombination
-Dormancy
--limited (asexual)
--long term (sexual)
-Analogous structures --sclerotia
-Taxonomically informative - What's the main difference between SPORANGIA and CONIDIA?
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Sporangia comes from preexisting cytoplasm
Conidia comes from newly synthesized cytoplasm - In what 3 Kingdoms would you find fungi?
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1) Protista
2) Chromista
3) Eumycota - What are some defining characteristics to the PROTISTAN FUNGI?
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-nutrition by ingestion
-live as individual cells or colonies
-sexual reproduction by spore formation (only walled stage)
-spore walls have peptidoglycan
**Dictyostelium (cellular slime molds) have cellulose in the spore wall** - What are the basic steps to ATTACHMENT, INFECTION AND COLONIZATION?
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-In nature, infective stage is motile flagellated zoospores – primary and secondary
-Zoospores find food a source by chemotaxis
-Attachment is followed by shedding flagella
-Infection requires growth of a penetrating hypha - What are the general roles of mycorrhizae?
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Essential for plant colonization of terrestrial environment
Mycorrhizal plant can exploit several times the volume of soil available to a non-mycorrhizal plant
-Environment to plant
-Plant to/from fungus
-Between plants – ecological integration
Pathogen relations
-Physical protection
-Antibiotics
-Increased plant vigour - What is ARBUSCULAR MYCORRHIZAE?
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-Common especially on herbaceous plants; some trees e.g. sycamore
-Formerly Zygomycota/Glomales
(now Glomeromycota)
-Large sorocarps and spores produced adjacent to roots, but subterranean
-Obligate biotrophs, each interaction temporally limited days to weeks
-Penetrates plant roots /cells - What are the main differences between Ectomycorrhizae and Endomycorrhizae?
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Ectomycorrhizae
-Deuteromyctes
-Mantle
-Root cells are surrounded but not invaded
Endomyccorhizae
-Zygomycete affinities
-No mantle
-Direct penetration of root cells - What is required for tip growth?
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Cell polarity (spatial specialization)
-localized wall deposition and maturation
Cell coordination
-cell growth and cytoplasm movement
Environmental responsiveness - What is Chytridium?
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-that thalloid/rhizoid thing
-attacks pine pollen
-super simple structure - Compare the zoospore encystment between Oomycetes, Chytridiomycetes and Plasmodiophoromycetes.
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Oomycetes
-land flagella first, and penetrate
Chytrids
-land body firts, crawls to location and then penetrates
Plasmodiophoromycetes
-lands body first and then invades (ie: no hyphal penetration)
**all zoospores end up losing flagella** - What are Neocallimastigales?
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-rumen fungi
-essential for cellulose breakdown
-possible control of rumen pathogens like nematodes
-Obligate anaerobes
-Distinctive multiflagellate zoospores that beat in unison
-Zoosporogenesis by cytoplasmic cleavage
-Flagella and basal bodies are shed during encystment - What are some beneficial roles of Chytridiomycota? Detrimental?
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Beneficial
-rumen fungi
-cellulose breakdown in soil
-Insect parasites as potential biocontrol agents
-Coelomyces – mosquitoes
Detrimental
-plant pathogens (ie: potatoe wart) - What is Synchitrium endobioticum?
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-Chytrid, particularly common on wet soil
-Resting spores long lived, ≥ 10 years
Spread on:
-warted seed potatoes
-soil in which they were grown (carried on tires, boots)
-manure from animals grazed on contaminated fields - What orders are found in Phylum Zygomycota? 3
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Mucorales
-No morphological genders
-Mating is determined by biochemical interactions: mating-type genes
-Zygos and ascos have two mating types: a/a, +/-
-Basidios have many mating types a & b loci, each with multiple alleles: Schizophyllum has ~28000 genders!!
Entomophthorales (insect fungi)
-Conidia attach
-Penetrate by enzymatic digestion
-Growth in insect as yeast or plasmodium or hypha (sp dependent)
-Conidia form at exoskeleton junctions
-Infection can induce positive phototropism
-Attack nervous system?
dying insects climb grass stems and cling there
--Improved spore dispersal
Glomales (mycorrhizae) - What are some characteristics to the order Kickxellales?
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-Discovered by
Prof. Kickx
-Saprobes with large asexual fruiting structures
-Probably for dispersal, like the seed coats of burr plants - What are Trichomycetes?
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-attached to the lining of the guts of living arthropods
-commensals and pathogens - Where can you find a hymenium layer?
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-Gills (Agaricus)
-Pores (Polyporales)
-Teeth (Hydnales) - What are the 3 form classes of Deuteromycetes?
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Blastomycetes – yeastlike, limited mycelium (e. g. Candida albicans)
Hyphomycetes – distinct mycelium limited conidioma (e. g. Aspergillus)
Coelomycetes – distinct mycelium with conidioma (e. g. Fusarium) - What is the progression of disease?
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1) Superficial – skin, hair, nails
2) Subcutaneous – peripheral tissues
3) Systemic – blood system, organs - In lichens, what are the advantages of the Mycobiont?
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-Transfer of carbohydrates from the photobiontglucose from cyanossugar alcohols from greens
-Some cyanobacterial photobionts will fix N2 supplying NH4+ - In lichens, what are the advantages of the Photobiont?
- -a place to live
- In lichens, are the some mutual benefits?
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-Some of the algalspecies are found free livingbut never in the lichen locationsIt is the fungal component that: a)allows the lichen to survive the extreme drying out
b) protects the algal cells from extreme light - What are some distinguishing characteristics of Foliose Lichens?
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-more or less flattened thallus
-upper and lower surfaces are easily identified - What are some distinguishing characteristics of Fruticose Lichens?
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-often grow erect
-no discernible upper or lower sides
-includes highly branched and shrubby forms - What are some defining characteristics to Crustose Lichens?
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-The somewhat classic form
-grow as crusts over substrate
-lower side is completely attached
-only removed with the substrate -
T/F
Lichens can have different numbers of PHOTOBIONTS. -
T
-The predominant photobiont determines the general morphology - What aspects about lichens make them so sensitive to pollution?
- -they soak up water like a sponge, therefor, if shit is polluted, they get polluted and die
- In class we discussed the ideas of mutualism and controlled parasitism with regards to the lichens. State your personal preference (mutalism vs controlled parasitism) for the description of the photobiont/mycobiont relationship. Give appropriate reasonin
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-be prepared to answer this
-book takes a mutualistic stance
-argue like the dickens
-best of luck - What are some major advances in Bryophytes, linking them to higher land plants?
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Antheridia and Aarchegonia -the male and female gametangia
Sporopollenin-walled spores -allows spores to resist decay and drying out
Multicellular Embryo
Multicellular Sporangia - What are some defining characteristics to HORNWORTS?
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-small phylum of about 100 speciessolitary chloroplasts, with pyrenoids
-thallus is relatively undifferentiated epidermis cells contain chloroplasts
-gametophyte is typically rosette shaped
-some species have extensive internal spaces often inhabited by Nostoc (cyanobacteria) - What are some defining characteristics to LIVERWORTS?
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-three main types based on gametophyte structure
-about 6000 species
-generally grow in moist shady areas some in water - How do LIVERWORTS asexually reproduce?
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-Some liverworts produce Gemma Cups
-Allows fragmentation for assexual reproduction
-Can be dispersed by rain or animals - Bryophytes and vascular plants share a number of characteristics that distinguish them from Charophytes and that adapt them for life on land. What are those characters?
- -be prepared to answer something like this...
- What are the 3 classes of Mosses?
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1)Sphagnidae: peat mosses
2)Andreaeidae: granite mosses
3)Bryidae: true mosses - How do mosses transport nutrients?
- -Many moss gametophytes and sporophytes have a central water conducting strand called a HADROM and a food conducting strand called the LEPTOM
- What is the INTERPOLATION HYPOTHESIS?
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-Gametophyte adapted to life in water
-Sporophyte evolved by delay of meiosisvas a response to life on land
-ie. it was inserted (interpolated) into the life cycle
Charophyte -> Bryophyte (Dependant Sporophyte Generation new on land) -> Vascular plants - What is the HOMOLOGOUS HYPOTHESIS?
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-Gametophyte and sporophyte generations are homologous (related by decent)to those of the algae
-therefore the sporophyte was present before the transition to land - Where did plants evolve from?
- -a Charophyte ancestor
- How do Bryophytes differ from eachother?
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differ in:
-stomata
-conducting tissue
-meristems - In your opinion, which of the bryophytes has the most highly developed sporophyte? Which has the most highly developed gametophyte? Why?
- -be prepared to answer this