Topic 11 Flashcards
What is the kingdom fungi?
molecular data place fungi much closer to Animalia
likely colonized land around the same time as plants (possibly even as symbionts of plants)
myco = fungus
What are the challenges faced by fungi?
no organs for digestion (no gut cavity), food must pass through cell wall
solution: extracellular digestion
no ability to move (terrestrial forms)
solution: they grow and expand themselves into new areas
What are the basic characteristics of fungi?
fungi secrete powerful enzymes (exoenzymes) outside their bodies
external digestion (saprophytes), break down large complex organic molecules –> absorb small simple ones
digests cellulose and lignin from plant tissues, and chitin and keratin from animal tissues
simple organic molecules absorbed by body of fungus, could be decomposers, parasites, or mutualists
How do fungi speed up the carbon cycle?
saprophytes are fungi that make their living by digesting dead plant material
the carbon cycle on land has two basic components:
- The fixation of carbon by land plants
- The release of CO2 from plants, animals, and fungi as the result of cellular respiration
for most carbon atoms, fungi connect the two components
What is the structure of fungi?
cell walls made of chitin
bodies of most fungi composed of hyphae, delicate tubes surrounding cytoplasm
interwoven hyphal mat called mycelium, acts as feeding network
grow in direction of food source
What are the two main types of hyphae?
septate: cross-walls (septa) dividing cells into separate chambers (holes in walls to allow cytoplasm and even nuclei to travel through)
coenocytic: lack cross walls (continuous cytoplasm with hundreds or thousands of nuclei
Why do fungi delay karyogamy?
has do with:
- Location of fertilization (fusion)
- Location for dispersal
What is fungal reproduction?
fungi produce spores asexually or sexually
spores always haploid (n), and produce hyphae
“spore” of fungi is different from the “spore” of plantae in that they are produced by both mitosis and meiosis , not just by meiosis as they are in plants
some do both at different times
other species only asexually
spores: resistant to desiccation and act as dispersal stages
What is the phylum chytridiomycota?
mainly freshwater, some in soil, estuaries, or on/inside guts of animals
free-living chytrids digest dead organic matter
parasitic chytrids digest tissues of living hosts
depending on chytrid species, host is plant, animal, or other fungus
chytrids implicated in global decline of amphibians
What is the phylum zygomycota?
live in soil and organic remains
few are parasites or predators
morphologically rather monotonous
What is the phylum glomeromycota?
all species engage in symbiotic relationships with roots of plants
90% of vascular plants species involved
supply minerals, nutrients, + H2O to roots in exchange for sugar (photosynthesis)
only asexual reproduction
What is the phylum ascomycota?
“sac-fungi”
largest phylum of fungi (~65,000 species)
range in size from single-celled yeasts to fist-sized truffles
defining feature is production of sexually produced spores in sac-like asci
What is the phylum basidiomycota?
“club-fungi”
sexual structures the classic mushrooms and toadstools
very important decomposers of dead plant matter (especially lignin)
many parasites of plants
cap contains thin vertical sheets of tissue called gills
gills lined with millions of basidia (spore production)
single mushroom can release a billion spores
What is mycorrhizae mutualisms with plants?
mycorrhizae represent mutualistic symbiosis of plant roots and fungi
fungus helps plants absorb minerals from soil, plant gives fungus carbohydrates
almost all vascular plant species have mycorrhizal associates
What is lichen?
symbiotic mixture of fungal hyphae and photosynthetic partner
green algae (chlorophyta) or cyanobacteria --> carbon, organic nitrogen fungi --> place to grow, protection, retains water and minerals
