Chapter 31 Fungi Flashcards
Are fungi heterotrophic or autotrophic?
heterotrophic
How do fungi feed?
absorption
Describe the two ways fungi use absorption.
- secrete hydrolytic enzyme to break down compounds
- may use enzymes to penetrate the walls of the plant cells
What are the two possible body structures of fungi?
- single celled yeast
- multicellular filaments
What are hyphae?
threadlike chains of cells that make up the mycelium
What strengthens fungi cell walls?
chitin- nitrogen containing polysaccharide
What is the mycelium?
mass formed by hyphae that infiltrates the material that the fungus feeds on
How do mycelium grow?
Grows rapidly as proteins and compounds are channeled through cytoplasmic streaming
What are hyphae divided by?
hyphae are divided by crosswalks called septa- septa have pores
What are fungi without septa called?
coenocytic fungi
What are haustoria?
specialized hyphae used to extract nutrients from and exchange nutrients with their hosts
What are mycorrhizae?
mutually beneficial relationships between fungi and plant roots
What is the function of mycorrhizae?
can improve delivery of phosphate ion and other minerals to plants and provide fungi with carbohydrates
What are the two types of mycorrhizae?
ectomycorrhizal fungi and arbuscular mycorrhizal fungi
What do ectomycorrhizal fungi do?
form sheaths of hyphae over the surface of a root and grow into the extracellular spaces of the rot cortex
What do arbuscular mycorrhizal fungi do?
extend branching hyphae through root cell walls and into tubes protruding into the cell
How do fungi reproduce?
produce spores through sexual or asexula lifestyles
What are mycelia?
the vegetative part of a fungus
How do mycelia communicate?
they release pheromones
What is the compatibility test?
two identical mycelia will not fuse– ensures variation
What is plasmogamy?
union of cytoplasms of two parent mycelia
What is heterokaryon?
“different nuclei” when mycelia first fuse and contain coexisting genetically different nuclei
What is dikaryotic?
haploid nuclei pair off two to a cell, one from each parent and remain separate
What is karyogamy?
haploid nuclei fuse forming diploid cells
Describe how molds reproduce asexually.
grow as filamentous fungi that produce spores by mitosis
Describe how yeasts reproduce asexually.
reproduce as budding yeasts- pinching of small bud cells off of parent cell
What are deuteromycetes?
fungi with no sexual stage
Describe the ancestor of fungi.
aquatic single celled flagellated protist
What are opisthokonts?
Opisthokonts- clade of protists with flagellum in the posterior
What are nucleariids?
amoebas that feed on algae and bacteria (single celled protists very closely related to fungi)
What are microsporidia?
unicellular parasites of animals and protist
Name the 5 main types of fungi.
Chytrids, zygomycetes, glomeromycetes, ascomycetes, basidiomycetes
Describe Chytrids.
- Live in lakes and soil
- Have flagellated spores called zoospores
Describe Zygomycetes.
- Resistant zygosporangium as sexual stage
- Zygosporangium is multinucleate structure, first heterokaryotic with many diploid nuclei then with many diploid nuclei after karyogamy
- Hyphae are coenocytic with septa only where reproductive cells are formed
- Pilobolus can aim and shoot their sporangia toward bright light
Describe Glomeromycetes.
- Form arbuscular mycorrhizae with plants
- 90% of all plant species have mutualistic partnerships with glomeromycetes
Describe Ascomycetes.
Sexual spores? Sacs? Fruiting bodies? Asexual spores?
- Sexual spores (ascospores) borne internally in sacs called asci
- Bear sexual stages in fruiting bodies or ascocarps, spore forming asci are found in the ascocarps
- Produce vast numbers of asexual spores (conidia)
- Conidia are produced externally at the tips of specialized hyphae called conidiophores often in clusters or long chains which may be dispersed by the wind
What are three examples of basidiomycetes?
mushrooms puffballs shelf fungi
What are basidiomycetes more commonly known as?
club fungi
Describe basidiomycetes
- Elaborate fruiting body (basidiocarp) containing many basidia that produce sexual spores (basidiospores)
- Long lived dikaryotic mycelium
- Produce “fairy rings”
Why are basidiomycetes significant?
- Two groups of destructive plant parasites: rusts and smuts
- Important decomposers of wood, able to break down the polymer lignin
What is a function of fungi in the atmosphere?
Fungi decompose the cellulose and lignin of plant cell walls and replenish the atmosphere with inorganic nutrients
What are the three main roles of fungi?
mutualists, decomposers, parasites
What are endophytes? What fungi type are they mostly and what do they do?
- Endophytes- fungi that live inside leaves or other plant parts without causing harm
- Mostly ascomycetes
- Make toxins that deter herbivores and increase plant tolerance to heat drought or heavy metals
How do fungi have a relationship with cattle?
break down plant material in the guts of cattle and other grazing animals
How do fungi have a relationship with leaf cutter ants?
Leaf cutter ants feed leaves to fungi and then eat the hyphae of the fungi
What is a lichen?
a symbiotic association between a photosynthetic microorganism and a fungus in which millions of photosynthetic cells are held in a mass of fungal hyphae
Describe the location of fungi and algae or bacteria in lichen?
- Fungi gives lichen overall shape and appearance and hyphae form tissues making up most of the mass
- Algae or bacteria occupy a layer beneath the lichen surface
What do fungi and algae do in a lichen?
- Algae provide carbon compounds, cyanobacteria fix and provide nitrogen
- Fungi provide photosynthetic partners with an environment to grow
- Allows for gas exchange, protects partner with pigments, retains water and minerals, secrete acids which aid in uptake of minerals
Describe two ways lichen may reproduce.
- Lichen may reproduce as two separate organisms: algae by asexual cell division, and fungi sexually by ascocarps or basidiocarps
- Lichen may reproduce as a unit through fragmentation or the formation of soredia- small clusters of hyphae with embedded algae
Name five fungi that infect plants.
- Cryphonectria parasitica- chestnut blight
- Fusarium circinatum- pine pitch canker
- Puccinia graminis- black stem rust on wheat
- Aspergillus- infiltrates unproperly stored grain and produces toxin
- Claviceps purpurea- grows on rye plants forming ergots- causes hallucinations
Name three fungi that infect humans.
- Mycosis- fungal infections
- Skin mycosis- ringworm
- Systemic mycosis spread through the body and cause very serious illness- lung spores
- Candida albicans- yeast infections
Name three practical uses of fungi.
- Aspergillus to produce citric acid for sodas
- Saccharomyces cerevisiae are used to produce alcohol, bread and for research
- Penicillium
