BIOL 171 - Protist & Fungi

What are the major characteristics of fungi?

• heterotrophic

• usually nonmotile,

• chitin cell walls

• mostly multicellular, although some are unicellular.

Approximately how many fungal species are estimated to exist?

About 145,000 to 1 million species.

What are two major ecological roles of fungi?

Decomposers and mutualists.

Why are fungi important to ecosystems?

They decompose organic matter and recycle nutrients, while also forming important mutualistic relationships.

What is the fungal cell wall made of?

Chitin.

Are fungi autotrophic or heterotrophic?

Heterotrophic.

Are most fungi multicellular or unicellular?

Most are multicellular, although some, such as yeast, are unicellular.

What is the largest organism mentioned in the fungi lecture?

The honey fungus, which is about 2.4 miles in size and about 2,400 years old.

What are hyphae?

Filamentous fungal structures that make up the main body of many fungi.

What is a mycelium?

A network or mass of fungal hyphae.

What is a fungal fruiting body?

A reproductive structure made from hyphae.

What is the function of a fungal fruiting body?

Reproduction.

How do fungi obtain nutrients?

They perform external digestion, dissolving food outside their cells and then absorbing the nutrients.

What is external digestion?

The process in which fungi dissolve food outside their cells before absorbing it.

What are saprobes?

Fungi that obtain nutrients from decaying organic matter.

Why are fungi important decomposers?

They break down organic matter and allow nutrients to be recycled through ecosystems.

What is a mycorrhiza?

A mutualistic relationship between fungi and plant roots.

Approximately what percentage of plants have mycorrhizal relationships?

About 80–90% of plants.

What are endophytes?

Fungi that live inside plants.

What is one mutualistic relationship between fungi and ants?

Ants feed fungi and then eat the fungi.

What is a lichen?

A symbiotic relationship w/ a fungus and an alga, cyanobacterium, or protist.

What are some major mutualistic relationships involving fungi?

Mycorrhizae with plant roots, endophytes living in plants, lichens, and relationships with animals such as ants and ruminants.

What are some harmful roles of fungi?

Some fungi are pathogens or parasites.

Why are fungi important to nutrient cycling?

Their decomposition of organic matter releases and recycles nutrients in ecosystems.

What is the relationship between fungi and early plants supported by fossils?

Fossils provide evidence of mutualistic relationships between fungi and early plants.

What is the significance of fossil fungal hyphae from about 440 million years ago?

They provide evidence of ancient fungi and their presence early in the colonization of land.

What clade includes fungi, animals, and their protistan relatives?

Opisthokonts.

What did opisthokonts evolve from?

A unicellular flagellated ancestor.

Why were fungi important during the colonization of land?

Fungi were among the earliest organisms to colonize land and formed mutualistic relationships with early plants.

What are cryptomycetes and microsporidians?

A sister group representing a basal fungal lineage.

What is notable about cryptomycetes and microsporidians?

Both are parasites.

What are chytrids?

Fungi characterized by producing flagellated spores called zoospores.

What are zoospores?

Flagellated fungal spores.

What are zoopagomycetes?

Fungi that form filamentous hyphae and parasitize organisms such as insects, sometimes inducing behavioral changes in their hosts.

What are Mucoromycetes?

A fungal group that includes molds and species that can be decomposers, parasites, pathogens, or plant mutualists.

What is the primary ecological role of many molds?

Decomposition.

What percentage of plant species have mutualistic partnerships with arbuscular mycorrhizae?

About 85%.

What are Ascomycetes?

A diverse fungal group ranging from unicellular yeasts to cup fungi and morels.

Why are Ascomycetes called sac fungi?

They produce spores in saclike structures called asci.

What is an ascus?

A saclike structure in which spores are produced.

What is an ascocarp?

The fruiting body of an Ascomycete.

What types of organisms are included among Ascomycetes?

Plant pathogens, decomposers, and symbionts.

What symbiotic relationships can Ascomycetes form?

They can form lichens, mycorrhizae, and relationships with plants as endophytes.

What are Basidiomycetes?

The club fungi.

What is a basidium?

A club-shaped cell where karyogamy and meiosis occur.

What processes occur in the basidium?

Karyogamy and meiosis.

What is a basidiocarp?

The fruiting body of a Basidiomycete, such as a mushroom.

What are mushrooms in terms of fungal structures?

Basidiocarps, or reproductive fruiting bodies of Basidiomycetes.

What is an important ecological role of Basidiomycetes?

They are important decomposers of wood.

Where are basidia typically found on mushrooms?

On the gills underneath the cap.

What are protists?

All eukaryotes that are not classified as plants, animals, or fungi.

Are protists a monophyletic group?

No, protists are a paraphyletic group.

Approximately how many protist species are mentioned in the lecture?

More than 100,000 species.

Where do most protists live?

Mainly in aquatic environments.

What nutritional strategies can protists have?

They can be autotrophic, heterotrophic, or mixotrophic.

Are protists always unicellular?

No. Most are unicellular, some are colonial, and a few are multicellular.

Are protists always free-living?

No. They can be free-living or parasitic.

What is endosymbiosis?

A relationship in which one organism lives inside the cell or cells of another organism, the host.

What is secondary endosymbiosis?

Eukaryotic cell engulfs and retains another eukaryotic cell that has already undergone primary endosymbiosis

What are some major ecological roles of protists?

Producers, symbionts, and parasites.

What are phytoplankton?

Photosynthetic organisms that form the base of the marine food web.

Why are diatoms ecologically important?

They are phytoplankton and form an important base of the marine food web.

What is the symbiotic relationship between coral and dinoflagellates?

Corals have a symbiotic relationship with dinoflagellates called zooxanthellae.

What are zooxanthellae?

Dinoflagellates that live symbiotically with coral animals.

What is the role of parabasalids in termite guts?

They help break down cellulose.

What is carrageenan used for?

It is derived from red algae and used to thicken dairy products.

What is algin used for?

It is derived from brown algae and used to thicken processed foods.

What are some human uses of seaweed?

Seaweed is eaten as food.

What is diatomaceous earth used for?

Cleaning, teeth whitening, and as an insecticide(pest control).

What are some important parasitic protists?

Trypanosoma, Plasmodium, and Phytophthora infestans.

What diseases are associated with Trypanosoma?

Sleeping sickness and Chagas disease.

What disease is caused by Plasmodium?

Malaria.

What disease is associated with Phytophthora infestans?

Potato blight.

What is coral bleaching identified as in the lecture?

An important phenomenon associated with the relationship between coral and its dinoflagellate symbionts.

What are the three major groups within Excavata mentioned in the lecture?

Diplomonads, parabasalids, and euglenozoans.

What are some characteristics of Excavata?

They have a cytoskeleton, modified mitochondria, unique flagella, and some have an excavated feeding groove.

What is an excavated feeding groove?

A groove on one side of the cell used in feeding by some Excavata.

What do diplomonads and parabasalids have in common?

They lack plastids and have reduced mitochondria.

What is a mitosome?

A reduced mitochondrial structure found in diplomonads.

Where do many diplomonads live?

In anaerobic environments.

What is an example of a diplomonad parasite?

Giardia intestinalis.

What are hydrogenosomes?

Modified/reduced mitochondria found in parabasalids.

What is an example of a parabasalid?

Trichomonas vaginalis.

What are euglenozoans?

A group that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites.

What structure is found inside the flagella of euglenozoans?

A spiral or crystalline rod.

What are the two major groups of euglenozoans mentioned?

Kinetoplastids and euglenids.

What is a kinetoplast?

An organized mass of DNA located within the single mitochondrion of a kinetoplastid.

What are kinetoplastids?

Euglenozoans with a single mitochondrion containing a kinetoplast

What diseases can trypanosomes cause?

Sleeping sickness and Chagas disease.

What can Chagas disease lead to?

Congestive heart failure.

What are euglenids?

Euglenozoans with one or two flagella emerging from a pocket at one end of the cell.

What makes some euglenids mixotrophic?

They can switch between autotrophic and heterotrophic nutrition depending on environmental conditions.

What is SAR?

A monophyletic supergroup consisting of Stramenopiles, Alveolates, and Rhizarians.

What does SAR stand for?

Stramenopiles, Alveolates, and Rhizarians.

What are stramenopiles?

A SAR group containing some of the most important photosynthetic organisms on Earth.

What flagellar characteristic is common in stramenopiles?

Most have a hairy flagellum and a smooth flagellum.

What are diatoms?

Photosynthetic stramenopiles that are phytoplankton and have silica, or glass, encasings.

What are oomycetes?

Stramenopiles that include parasites, water molds, white rusts, and downy mildews.

What is an example of an oomycete-related disease?

Potato blight.

What are brown algae?

Photosynthetic stramenopiles that include seaweeds.