Protist Quiz
Dinoflagellates
("whirling flagellates") are mostly marine single-celled alveolate protists. Some are predators or parasites; others are photosynthetic members of the plankton or symbionts in corals. Blooms of certain species cause "red tides" that can sicken humans and kill aquatic organisms. Some of these toxins kill directly
Flagella
A long threadlike appendage
The Alveolates
Ciliated protozoans, dinoflagellates, and apicomplexans are single-celled photoautotrophs, predators, and parasites. Their shared trait is a unique layer of sacs under the plasma membrane
Stramenopiles
Colorless filamentous molds, photosynthetic single cells, and large seaweeds belong to the stramenopile lineage. Most are photosynthetic, with a brown accessory pigment (fucoxanthin) • Major components of phytoplankton
Cilia
Hair like projections that extend from surface of the cell
Cyclic AMP
In the cellular slime mold Dictyostelium, the nucleotide cyclic AMP is the signal that induces solitary amoeboid cells to stream together • Triggers gene expression which causes cells to differentiate into components of a stalk or spores. Also functions in signaling pathways of multicelled organisms
Single-celled
Most protists are __________________, but some are colonial or multicelled
autotrophs or heterotrophs
Protists can be _______________________, and a few can switch between modes
Chloroplasts
Red and green algae share a common ancestor with ___________ derived from cyanobacteria. Red algae and green algae are photosynthetic single cells and multicelled seaweeds.
Dormant Cyst
Some single-celled protists can develop into a nonmotile, _______________ during hard times
Pseodopod
Temporary Projection of the cytoplasm
Slug
When food runs out, thousands of cells form a "_____" that migrates, forms a fruiting body, and produces spores and new diploid amoeboid cells • Example: Dictyostelium discoideum
Most and some
________ ciliates are free-living predators that hunt bacteria, other protists, and one another in freshwater habitats and the oceans. Example: Paramecium ________ ciliates are parasites of animals • Balantidium coli is a parasite of humans
Amoebozoans
amoebas and slime molds
Slime molds
are "social amoebas" • Plasmodial and cellular slime molds
Protists
are eukaryotic organisms that are not fungi, plants, or animals. based on gene sequences, were grouped into many lineages of mostly single celled eukaryotes. no single trait is unique to them other than the presence of the nuclear envelop.
Euglenoids
are flagellated protists related to kinetoplastids that do not infect humans • Most prey on bacteria • Some have chloroplasts that evolved from green algae and can detect light with an eyespot • Most live in freshwater and have contractile vacuoles that expel excess water
Kinetoplastids
are flagellated protozoans with a single large mitochondrion
Radiolarians
are heterotrophic protists with silica (glassy) shells beneath their plasma membrane, most are part of the marine plankton - vacuoles filled with air keep them afloat. single celled and cytoplasm extends through many pores
Ciliates
are heterotrophic single cells that move about with the help of cilia, reproduce asexually by binary fission or sexually by conjugation
Red algae
are mostly multicelled marine algae that live in clear, warm waters. Red accessory pigments (phycobilins) allows them to live at greater depths than other algae. Life cycles vary and are often complex, with both asexual and sexual phases; there is no flagellated stage
Brown algae
are multicelled protists that live in temperate or cool seas; ranging from microscopic filaments to giant kelp. Some are used commercially: Thickeners (algins), food, fertilizer, herbal supplements (bladderwrack)
Apicomplexans
are parasitic alveolates that spend part of their life inside host cells. infect a variety of animals from worms to insects to humans where the lifecycle may involve more than one species
Green Algae
are photosynthetic single-celled and multicelled protists. Like land plants, they have cellulose in their cell walls, store sugars as starch, and have chloroplasts descended from cyanobacteria. Most are chlorophytes Chlorella: Single celled, grown as health food • Chlamydomonas: Single celled, freshwater alga • Volvox: Colonial, freshwater alga • Cladophora: Forms long filaments • Ulva: "Sea lettuce" • Codium fragilis: Branching marine alga
Foraminiferans
are single celled protists that make calcium carbonate shells from CO2, heterotrophic single celled and cytoplasm extends through many pores • Helps stabilize atmospheric CO2 levels and buffers pH of seawater • Shells accumulate as chalk or limestone Most live on the seafloor; others drift as part of the plankton
Diatoms
are single-celled or colonial protists that have a two-part silica shell • Shells accumulate on the seafloor (diatomaceousearth)
Flagellated protozoans
are single-celled protists covered by a pellicle. They swim in lakes, seas, and the body fluids of animals. They are typically heterotrophic and reproduce asexually by binary fission. Includes single-celled predators and some human parasites
Diatoms and Brown Algae
are stramenopiles, most of which are photoautotrophs
Plasmodium
causes malaria
Toxoplasma gondii
causes toxoplasmosis
Green Algae
chlorophyte algae, charophyte algae, and land plants
Alveolates
ciliates, dinoflagellates, apicomplexans
Flagellated Protozoans
euglenoids, diplomonads, parabasalids, and trypanosomes
Water molds or oomycotes
form a mesh of filaments made up of diploid cells with cellulose cell walls. They decompose organic matter in aquatic habitats, are aquatic parasites (Saprolegnia), or infect plants. include economically and ecologically important plant pathogens that infect a wide variety of crop plants, as well as forest trees • Phytopthora infestans ruined Irish potato crops • Phytopthora ramorum recently infected North American Forests
Sargassum
forms large floating mats • Important Atlantic habitat (Sargasso Sea)
Alternation of generations
haploid and diploid multicelled forms
Diplomonads and parabasalids
have multiple flagella and live in oxygen-poor waters (anaerobic flagellates) • Hydrogenosomes produce ATP anaerobically Some infect humans and cause disease • Giardia lamblia is an intestinal parasite • Trichomonas vaginalis causes a sexually transmitteddisease
Trypanosomes
include human pathogens that are transmitted by insects examples: • African sleeping sickness (T. brucei) is spread by tsetse flies • Chagas disease (T. cruzi) is spread by bloodsucking bugs
Chlorophyte Algae
include several lineages that form a clade with land plants • Desmids: A single-celled, freshwater group • Spirogyra: Forms long filaments • Stoneworts (Chara): Closely related to land plants
Giant kelp or Macrocystis
is the largest protist • Life cycle: alternation of generation with multicellular haploid and diploid bodies and a dominant sporophyte generation • Ecologically important kelp forests (Pacific)
Amoebas
live as single cells • Example: Amoeba proteus, a freshwater predator
Diploid-dominated life cycle
only gametes are haploid
Pellicle
proteins that help cells retain shape
Amoebozoans
send out pseudopods, move about, and capture food. Most have no cell walls, shell, or pellicles. They are the closest living protistan relatives of fungi and animals
Plasmodial slime molds
spend most of their lives as a plasmodium • A streaming multinucleated mass that feeds on microbes and organic matter • Undergoes mitosis many times without cell division • Develops into spore-bearing fruiting bodies
Cellular slime molds
spend most of their lives as individual amoeboid cells that feed on bacteria and reproduce by mitosis
Stramenopiles
water molds, diatoms, brown algae
Haploid-dominated life cycle
zygote is the only diploid cell