Unit 2 Flashcards
Kingdom Fungi
-decomposers
-heterotrophs (w/ extracellular digestion)
*saprobes
*symbionts
-chitin-based cell wall
Saprobes
nutrients from dead organic matter
Symbionts
nutrients from living organic matter
General Morphology of Kingdom Fungi
-thallus/mycelium-body of fungal organism
-hyphae-filaments that make up thallus/mycelium
*septate or coenocytic
-haustoria-specialized hyphae that release exoenzymes for extracellular digestion
Septate
cell walls partition cells
Coenocytic
no cell wall partitions
Reproduction of Fungi
1) fertilization (syngamy) occurs with fusion of cytoplasm from 2 different cell types (plasmogamy)
2) however, in many fungi mitotic cell divisions begin before nuclei fuse (karyogamy) creating a transition ploidy “n+n” or dikaryon/heterokaryon b/c 2 haploid nuclei are from different individuals
3) karyogamy occurs which allows meiosis to occur to produce genetically unique spores
Phylum Zygomycota
-spores dispersed by air
-hyphae w/ few or no septa (coenocytic)
-rhizopus=black bread mold
Reproduction of Phylum Zygomycota
1) mycelia have various mating types (-) or (+)
2) neighboring mycelia of different mating types form hyphal extensions (gametangia), each of which encloses several haploid nuclei
3) plasmogamy occurs, which creates a zygosporangium (heterokaryotic) that contains multiple haploid nuclei from the 2 parents
4) zygosporangium develops a rough, thick-walled coating that can resist harsh conditions for months
5) when conditions are favorable, karyogamy occurs, then meiosis
6) zygosporangium germinates into a sporangium on a short stalk
7) sporangium disperses genetically diverse haploid spores
8) spores germinate and grow into new mycelia
9) mycelia can also reproduce asexually by forming sporangia that produce genetically identical haploid spores (meaning they have undergone mitosis)
Phylum Ascomycota
-largest class
-free-living and symbiotic
-spores dispersed by air
-septate hyphae w/ preforations
-ascus/spore sac forms ascocarp
-representatives-peziza, saccharomyces/yeast, claviceps & rye ergot, penicillin (first antibiotic), morels and truffles, cheese, wine, and bread
Reproduction of Phylum Ascomycota
1) ascomycete mycelia can reproduce asexually by producing pigmented haploid spores (conidia)
2) neurospora can also reproduce sexually by producing specialized hyphae. conidia of the opposite mating type fuse to these hyphae
3) dikaryotic hyphae that result from plasmogamy produce many dikaryotic asci
4) karyogamy occurs within each ascus, producing diploid nucleus
5) each diploid nucleus divides by meiosis, yielding 4 haploid nuclei
6) each haploid nucleus divides once by mitosis, yielding 8 nuclei. cell walls and plasma membranes develop around the nuclei, forming ascospores (LM)
7) ascospores are discharges forcibly from the asci through an opening in the ascocarp. germinating ascospores give rise to the new mycelia
Phylum Basidiomycota
-spores dispersed by air
-septate hyphae
-basidium->basidiocarp
-representatives-mushrooms, toadstools, puffballs, bracket fungi, world’s largest organism (fairy rings)
Reproduction of Phylum Basidiomycota
1) two haploid mycelia of different mating types under plasmogamy
2) dikaryotic mycelium forms, growing faster than, and ultimately crowding out, the haploid parental mycelia
3) environmental cues such as rain or changes in temp induce the dikaryotic mycelium to form compact masses that develop into basidiocarps
4) basidiocarp gills are lined with terminal dikaryotic cells called basidia
5) karyogamy in each basidium produces a diploid nucleus which then undergoes meiosis
6) each diploid nucleus yields 4 haploid nuclei, each of which develops into a basidiospore
7) when mature, the basidiospores are ejected than disperses by wind
8) in a suitable environment, the basidiospores germinate and grow into short-lived haploid mycelia
Phylum Deuteromycota
-imperfect fungi
-sexual reproduction not observed
-asexual condiospores produced
-representatives-molds, ringworm, predatory fungus
Mycorrhizae
mutualistic relationship with roots of most plants and fungi. host plants provide food for the fungus while water and mineral uptake by plants are enhanced by fungal hyphae
Lichens
mutualistic relationship with fungi and algae/cyanobacteria. algae provide food while fungi provide structural positioning for photosynthesis mostly outside of aquatic environments
-lichens are important pioneer species that establish terrestrial ecosystems
-crustose-crust like
-fruiticose-shrub like
-foliose-leaf like
Kingdom Plantae
photosynthetic autotrophs and cellulose-based cell wall
-land colonization by plants occurred about 400 mya
-green algae is a likely ancestor (charamycean)
Alternation of Generations
-fertilization (syngamy) of 2 different gametes/cell types (plasmogamy)
-immediately (before mitotic cell divisions), creating diploid zygote
-development of diploid plant goes through mitotic cell divisions that create structures that will go through meiosis (spores)
-these spores collectively produce the sporophyte
-haploid spores germinate and develop (via mitosis) into gametophytes which produce identical gametes via mitosis
-sporophyte and gametophyte alternate
Homospory
sporophyte produces only one kind of spore that germinates into gametophyte individual that produces both egg and sperm
Heterospory
sporophyte produces two kinds of spores
-megaspore-germinates into gametophyte that only produces eggs
-microspore-germinates into gametophyte that only produces sperm
Gametophyte and Sporophyte
-isomorphic-gametophyte and sporophyte are indistinguishable, rare
-heteromorphic-gametophyte and sporophyte are distinct
Gamete Evolution
developed in many plant-like protists
-isogamy-gametes identical in size and motility
-anisogamy- gametes differ in size but both motile
-oogamy-large immotile gamete = egg; small, motile gamete=sperm
Reproduction of Kingdom Plantae
1) the gametophyte produces haploid gametes by mitosis
2) 2 gametes unite (fertilization) and form diploid zygote
3) zygote develops into multicellular diploid sporophyte
4) sporophyte produces unicellular haploid spores by meiosis
5) spores develop into multicellular haploid gametophytes
New Problems Facing Land Plants
-obtaining water
-transporting water and nutrients
-water loss
-gas exchange
-gravity
-reproduction
-temperature flux
Land Plant Features
-chlorophyll A & B
-starch storage
-gametes protected
-stomata
-wax surfaces
-root system
-conduction tissue
-support tissue
Nonvascular Plants
-lack vascular tissues
-gametophyte->sporophyte
-small and live in moist environments
-phylum byrophyta-mosses
-phylum heptatophyta-liverworts
-phylum anthocerophyta-hornworts