Fungi 1 Flashcards

Question

Medicines: Statins

Answer 1

Used to lower low density lipoproteins (e.g. Lovastatin and Squalestatin)

Answer 2

Used to lower blood pressure

Answer 3

Single-celled fungal form -Require moist environments (plant sap, animal tissues) with a ready supply of soluble nutrients (sugars and amino acids)

Answer 4

Multicellular fungal form -Most prevalent form of fungi -Typically form a network of tiny filaments

Answer 5

Each of the fungal filaments that make up the body of a fungus -Consist of tubular cell walls surrounding the plasma membrane and cytoplasm of the fungal cells

Answer 6

An interwoven mass of hyphae -Infiltrates the material on which the fungus feeds -maximizes surface-to-volume ratio to make feeding very efficient

Answer 7

The above groud spore-bearing fruiting body of a fungus ("mushroom") -The mushroom and its subterranean mycelium are a continuous network of hyphae

Answer 8

Cross-walls that divide hyphae into cells -Typically fungal septa have pores large enough to allow ribosomes, mitochondria, and nuclei to flow from cell to cell

Answer 9

Fungi that lack septa -Consist of a continuous cytoplasmic mass having hundreds or thousands of nuclei -Result from the repeated division of nuclei without cytokinesis

Answer 10

Reproductive structure -adapted for dispersal and survival -may be generated asexually or sexually -germinate in moist, nutrient-rich places, to produce a new mycelium -some species can produce and release billions of spores in a single dispersal event

Answer 11

Sexual signaling molecules -Bind to cellular receptors -Trigger the growth of hyphae toward the source -Result in cellular fusion between the two compatible partners

Answer 12

The sexual union (fusing) or two haploids (n) parent mycelia -produce heterokaryotic cells: genetically different nuclei co-existing in the same cell -not diploid (2n) because the genetic material from each parent is maintained in separate nuclei (Described as n + n)

Answer 13

Fusing of the two nuclei on a heterokaryotic cell -May occur hours, days, or centuries after plasmogamy -Produces a temporary diploid cell (zygote)

Answer 14

A diploid cell resulting from the fusion of two haploid nuclei

Answer 15

Muclei of fungal hyphae are haploid (n)

Answer 16

Temporarily during sexual reporudction

Answer 17

Producing spores

Answer 18

1. Pheromones secreted by two different mating types cause hyphae to grow close together 2. Plasmogamy occurs, producing heterokaryotic cells (typically diplokaryotic) 3. Karyogamy occurs, producing a temporary zygote (diploid) 4. Meiosis occurs creating four haploid nuclei from the diploid zygote 5. Spores are created when hard walls form around each haploid nucleus; the durable meiospores are then released upon maturity and dispersed by the wind 6. Germination occurs when the spores land in a hospitable environment (moist and nutrient-rich), resulting in new haploid hyphae that grow into a new mycelium

Answer 19

1. A diploid parent cell produces a small protuberance that grows to form a bud 2. Mitosis occurs, duplicating the parental nucleus, and one nucleus migrates into the developing bud 3. The bud continues to grow until it separates from the mother, forming a new cell

Answer 20

1. A diploid cell can undergo meiosis to create Mat a and Mat α haploid cells 2. Two haploid cells of different mating types secrete pheromones 3. Reception of the opposite pheromone causes cells to change shape and enter the Schmoo stage 4. Cells come together; cytoplasms fuse and then nuclei fuse to form a diploid zygote 5. The cell then reenters the cell division cycle and gives rise to its first diploid bud 6. The bud matures into a fully formed daughter cell and separates from the mother Note: the diploid zygote can undergo sporulation, but only under high-stress conditions (e.g. nutrient starvation); these spores can later germinate to produce Mat a and Mat α haploid cells

Answer 21

A group of organisms that consist of a common ancestor and all its lineal descendants

Answer 22

Meaning: posterior flagella Common ancestor: unicellular flagellated ancestor Lineal descendants: Animals, Flagellated protists, Fungi

Answer 23

Fungi may have colonized land before plants -probably existed along with cyanobacteria and algae as among the first terrestrial colonizers  405 million year old plant fossils show evidence of mycorrhizal relationships  The earliest land plants lacked roots, limiting their ability to extract nutrients from the soil  Fungal partners likely helped transfer soil nutrients to the early land plants via extensive mycelia

Answer 24

Phylum: Chytridiomycota Primarily aquatic (lakes, moist soil, and marine) One of the earliest fungi to diverge from the protists Possess flagellated spores (Zoospores) The only fungi with true motility Reminiscent of protist ancestry During sexual reproduction they produce a globular fruiting body that forms multicellular, branched hyphae The name, Chytrid, comes from this globular fruiting body (chytridion = “little pot”) Ecological roles  Most are decomposers  Some are mutualists (e.g. ruminants)  Some are parasites o 1999: Batrachochytrium dendrobatidis described o Infects the skin of amphibians o Has resulted in devastating population declines and species extinctions o “Chytridiomycosis”

Answer 25

Phylum: Zygomycota Coenocytic hyphae Form characteristic Zygosporangia Formed through the fusion (“zygos”) of two gametangia (specialized hyphal strands) The name of this group, Zygomycota, refers to this structure, zygosporangium, formed during sexual reproduction Form characteristic zygosporangia Thick-walled structure Desiccation- and chemically-resistant Germinates into a sporangium on a short stalk Roles  Primarily terrestrial living in soil or on decaying plant or animal material  Includes many of the fast-growing molds that cause breads and fruits to rot  Primarily terrestrial living in soil or on decaying plant or animal material  Includes species (Pilobolus sp.) that can aim and shoot sporangia toward light o Grow in animal dung o Clear subsporangial vesicle acts as a lens to heat up and direct the fruiting structure toward light o Explodes to spread spores toward sun-drenched grass, away from dung  Can cause disease in humans and animals o Allergies (Sinusitis) o Skin and GI infections, but only in immunocompromised hosts

Answer 26

Phylum: GlomeromycotaGlomus (latin): “ball” Refers to its characteristically shaped Glomerospores Newly defined phylum Previously assigned to Zygomycota Reclassified based on DNA sequence Only observed to replicate asexually, but appears to have the genes for meiosis, suggesting an as yet unobserved sexual reproductive mechanism Nearly all form arbuscular mycorrhizae with plants  Fungus mycelia extend into soil to dissolve and uptake minerals (PO4, Zn, Cu, etc.) o Nourishes plant root cells via haustoria  Plant provides sugars and amino acids Recent studies regarding mycorrhizal associations  >80% of terrestrial plants have a mycorrhizal relationship with Glomeromycetes  Most Glomeromycetes are dependent on the plant- fugus relationship; unable to grow independently Recent studies regarding mycorrhizal associations  Many plants depend on the mycorrhizal association and fail to thrive without the fungal symbiont

Answer 27

 Phylum: Ascomycota  Range in size from unicellular yeasts and filamentous molds to elaborate cup fungi and morels  Include: o Saccharomyces species o Cup fungus o Morel o Penicillium species o Aspergillus species  Reproduction  Asexual reproduction is the dominant form of propagation o Spores (conidia) form on the ends of specialized hyphae (conidiophores)  Sexual reproduction o The heterokaryotic hyphae that result from plasmogamy produce many dikaryotic asci o The heterokaryotic hyphae that result from plasmogamy produce many dikaryotic asci o Karyogamy occurs within each ascus producing a diploid nucleus o Each nucleus divides by meiosis yielding four haploid nuclei o Each haploid nucleus divides once by mitosis, yielding eight nuclei; cell walls develop around the nuclei forming ascospores o The ascocarp (a collection of asci) forms and, when fully developed, discharges the ascospores forcibly  Named for the characteristic ascus structure formed during sexual reproduction  Roles  Important decomposers of plant material  Includes edible species (morels, truffles, and beneficial yeasts)  Some form beneficial Ectomycorrhizal associations with plants  Some serve as the fungal partner in lichens  Includes many animal and plant pathogens  Aspergillus -> Aflatoxins (toxin in peanuts, hay, & grains)

Answer 28

 Phylum: Basidiomycota  Reproduction  Primarily sexual reproduction o After plasmogamy, the dikaryotic mycelium grows faster than, and ultimately crowds out, the haploid parental mycelia o Environmental cues (rain, temperature changes, etc.) induce the dikaryotic mycelium to form compact masses that develop into basidiocarps o Environmental cues (rain, temperature changes, etc.) induce the dikaryotic mycelium to form compact masses that develop into basidiocarps o Karyogamy in each basidium produces a diploid nucleus, which undergoes meiosis with each diploid nucleus yielding four haploid nuclei, each of which develops into a basidiospore o When mature, the basidiospores are ejected and dispersed by the wind o When mature, the basidiospores are ejected and dispersed by the wind o Basidiospores germinate in suitable environments to form haploid mycelia  Includes the mushrooms, puffballs, and shelf fungi  Some are edible  Some are deadly  Some are hallucinogenic  Includes many of the rusts and smuts  Cause billions of dollars in damage to crop plants  Responsible for Fairy rings  Once the fruiting bodies are constructed, mushrooms rapidly absorb water & “pop” up over night  Mycelium grows at a rate of ~30 cm/year  Some giant fairy rings are centuries old  Often produce rings of enhanced grass growth  Important decomposers of wood  Wood is a complex mixture of cellulose, hemicelluloses, and lignin  Lignin serves as a cement, a stiffening agent, and a barrier to enzymatic degradation  Makes wood recalcitrant to decomposition  Basidiomycetes are one of the few organisms that can completely mineralize wood, including the lignin component

Answer 29

 Note: Classical taxonomy classifies fungi based on structures formed during sexual reproduction  Chytridiomycota: chytridion = “little pot” Contains its zoospores  Zygomycota = zygosporangium holds its sporangiospores  Ascomycota = ascus holds its ascospores  Basidiomycota = basidium holds its basiospores  Deuteromycetes are those fungi that do not reproduce sexually and have no sexual reproductive features  ...or, at least, contains those whose sexual reproduction has not yet been observed.  Deuteromycetes is not a true phylum  Only a temporary holding group  Probably includes members of each identified fungal phylum...and maybe