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The informal name of the "kingdom" of mostly unicellular eukaryotes. (Not really a kingdom, it's a paraphyletic group because it leaves out some descendents. Protista is no longer valid as a kingdom.)
A cell with a nucleus and organelles. More complex than prokaryotic cells, which lack a nucleus and organelles.
endosymbiosis (serial endosymbiosis theory; SET)
Endosymbiosis is the process in which unicellular organisms engulf other cells, which become "endosymbionts" and ultimately organelles in the host cell. SET says that the endosymbionts transferred some of their own DNA into the host cell's nucleus over time. Example of endosymbiosis: uptake of mitochondria.
symbiosis today - Mixtotricha paradoxa, cyanobacteria
Plastids evolved by endosymbiosis of a photosynthetic cyanobacterium (primary endosymbiosis). This led to the evolution of red and green algae. The algae were then engulfed by other heterotrophic eukaryotes (secondary endosymbiosis), resulting in photosynthetic eukaryotic cells.
Membrane-bound bodies within a cell that carry on specific functions, such as chloroplasts, mitochondria, etc.
Animal-like protists. May have:
- pseudopodia (i.e., amoeba)
or none of the above (i.e., Plasmodium)
- Photosynthetic: "phototrophs" ("eat light")
- Have flagella
Fungus-like protists. Heterotrophs.
Absorb nutrients from the environment.
autotrophs - ex. phototrophs
Create their own food. Phototrophs: photosynthetic.
Refer to a unicellular, eukaryotic protist moving (and eating) by using pseudopodia. Amoebas reproduce ASEXUALLY by binary fission. Amoebas can be shelled (with tests) or unshelled.
Temporary projections of eukaryotic cells. Cells having this faculty are generally referred to as amoeboids. Pseudopodia extend and contract by the reversible assembly of actin subunits into microfilaments. Filaments near the cell's end interact with myosin which causes contraction. The pseudopodium extends itself until the actin reassembles itself into a network. This is how amoebas move, as well as how they engulf their food.
The cellular process of engulfing solid particles (i.e., food) by the cell membrane to form an internal phagosome by protists. Phagocytosis is a specific form of endocytosis.
A cavity within the amoeba in which food is digested.
Breaks down the amoeba's food within the food vacuole.
Foraminiferans (forams) named for porous, multichambered shells called tests. Pseudopodia extend through pores in the test. Tests form an extensive fossil record.
Porous, multichambered shells of foraminiferans that have created a huge fossil record. Radiolarians also have tests.
Have tests fused into one delicate piece. Use pseudopodia to engulf microorganisms through phagocytosis.
Have one or more flagellum to move.
Tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and functions in locomotion.
Protist that causes sleeping sickness.
Diseased caused by Trypanosoma (which is passed by the tsetse fly). The tsetse fly bites a human and makes a blood meal, and injects metacyclic trypomastigotes into the bloodstream, which multiply by binary fission in various body fluids and cause disease.
When a tsetse fly makes a blood meal (i.e., bites THAT person), the fly ingests the metacyclic trypomastigotes, which transform into procyclic trypomastigotes and multiply by binary fission. Procyclic trypomastigotes leave the fly's midgut and transform into epimastigotes, which multiply in the salivary gland and transform into metacyclic trypomastigotes. The tsetse fly makes a blood meal and it starts over again ...
See "sleeping sickness."
An organism that can carry a parasite, and is responsible for infecting other organisms (host) with that parasite. Not harmful on its own.
Examples: tsetse fly (Trypanosoma/sleeping sickness); Anopheles mosquito (Plasmodium/malaria).
A group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Water currents generated by the flagellum push free-swimming cells along, as in animal sperm. In contrast, most other flagellates are pulled by their flagella.
A group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella. Ciliates tend to be large and very complex. Example: paramecium.
A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body.
9 + 2 pattern of microtubules
A eukaryotic flagellum/cilia is a bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules. The so-called "9+2" structure is characteristic of the core of the eukaryotic flagellum/cilia called an axoneme.
Ciliates have a micronucleus, which functions during conjugation (a sexual process that produces genetic variation).
Ciliates also have a macronucleus. During asexual reproduction (binary fission), the macronucleus disintegrates and a new is formed by the cell's micronuclei. The macronucleus contains multiple copies of the cell's genome.
Conjugation: Two compatible ciliates (i.e., paramecium) align and partially fuse. Meiosis of micronuclei produces four haploid micronuclei in each cell. Three micronuclei in each cell disintegrate. The remaining divides by mitosis. The cells swap one micronuclei. The cells separate.
Reproduction: Then the two micronuclei in one cell fuse. Three rounds of mitosis produce eight micronuclei. Four micronuclei become macronuclei. Two rounds of cytokinesis yield four daughter cells, each with one micronuclei and one macronuclei.
The pellicle is a thin layer supporting the cell membrane in various protozoa, protecting them and allowing them to retain their shape.
A structure in the cortex of certain ciliate and flagellate protozoans consisting of a cavity and long, thin threads that can be ejected in response to certain stimuli. Trichocysts may be widely distributed over an organism or restricted to certain areas (e.g., tentacles, papillae, around the mouth).
P. Apicomplexa / Sporozoa
Apicomplexans are parasites of animals, and some cause diseases in humans. Most have asexual and sexual stages that require 2 or more different host species for completion.
parasitic w/complex life cycles
Apicomplexans have both asexual and sexual life cycle stages.
infective spore stage
The parasite spreads through the host as tiny infectious cells called sporozoites.
Protist that causes malaria. Requires both mosquitoes and humans to complete its life cycle. Not photosynthetic, but has a modified plastid, most likely from a red algae.
Disease caused by Plasmodium. Kills 2+ million people every year.
Infected Anopheles mosquito bites a person, injecting Plasmodium sporozoites through its saliva. Sporozoites enter the person's liver cells. After several days, the sporozoites (which are haploid) undergo divisions and become merozoites.
Merozoites (also haploid) use their apical complex to penetrate red blood cells, then divide asexually inside the RBCs. After 48 or 72 hours, merozoites exit the RBCs, causing chills and fever. Some merozoites infect other RBCs. Some form gametocytes (also haploid).
The activated, intracellular feeding stage in the apicomplexan life cycle. After gorging itself on its host, the trophozoite undergoes schizogony and develops into a schizont, later releasing merozoites.
Another Anopheles bites the infected person and picks up the gametocytes (along with blood). Gametocytes form gametes. Fertilization occurs in the mosquito's digestive tract, forming a DIPLOID zygote (only diploid stage). The zygote develops into an oocyst, which releases 1000s of sporozoites, which migrate to the mosquito's salivary gland. The mosquito bites another person and the process begins again ...
The type of mosquito that carries Plasmodium (the parasite that causes malaria).
PLANT LIKE (algae)
Has a pocket at one end of the cell from which one or two flagella emerge. Many species are mixtotrophs: autotrophic in sunlight, but w/o light available, become heterotrophic, absorbing nutrients from environment. Some engulf prey by phagocytosis. Has a pellicle to provide form; lacks a cell wall. Euglenas reproduce ASEXUALLY only.
The CV pumps excess water out of the cell. In freshwater environments the concentration of solutes inside the cell is higher than outside the cell (i.e., the environment is hypotonic). Under these conditions water flows from the environment into the cell by osmosis. The CV serves as a protective mechanism that prevents the cell from absorbing too much water and possibly exploding. Euglena contains this.
stigma/eyespot - photopositive
Eyespot: Euglena's pigmented organelle that functions as a light shield, allowing light from only a certain direction to strike the light detector.
Light detector: Detects light that is not blocked by the eyespot, so Euglena moves toward light of appropriate intensity (enhances photosynthesis).
Unicellular, photosynthetic algae with a unique, two-part wall of hydrated silica. Usually reproduce asexually, occasionally sexually.
During asexual reproduction, one of the diatom daughter cells is smaller than the other. This continues until a certain size is reached, and then sexual reproduction happens (can't go below a certain size).
Photosynthetic algae. Components of both marine and freshwater phytoplankton. Have 2 flagella. Each species has a characteristic shape; often is reinforced by internal plates of cellulose.
algal blooms (red tides)
Caused by dinoflagellates (we often don't know why). VERY poisonous nerve toxin secreted; can't swim in the water or eat shellfish when this happens.
Largest and most complex algae; all are multicellular. Include many species commonly called "seaweeds." Giant seaweeds called kelps live in deep parts of the ocean. Body is plant-like. Have flagella.
holdfast, stipe, blade
The holdfast is the root-like part of the brown algae; it anchors the stem-like stipe, which in turn supports the leaf-like blades.
Genus of brown algae; also the namesake of the Sargasso Sea: place in the North Atlantic where there are no prevailing winds, and thus large beds of seaweed.
Heliobacterium and brown algae have similar pigments.
Usually reddish; not always. Smaller, more delicate than brown algae. Most abundant large algae in coastal waters of the tropics. Have flagella.
Made from red algae.
Cyanobacteria have similar pigments to red algae.
Named for their green chloroplasts. Plants are descended from green algae. Two main groups: chlorophytes and charophyceans. There are unicellular, filamentous, colonial, and multicellular species.
Examples: volvox, sea lettuce (ulva). Have flagella.
Prochloron and green algae have similar pigments.
cellular slime molds (P. Acrasiomycota)
Form MULTICELLULAR aggregates (unlike SINGLE CELL plasmodial slime molds). Cells are separated by membranes. Cells feed individually, but can aggregate to form a fruiting body (which releases haploid spores, which form into emerging amoeba, which then can aggregate). Reproduce both ASEXUALLY and SEXUALLY, with a diploid zygote. Experimental model for studying the evolution of multicellularity.
Multicellular aggregates of cellular slime molds form a multicellular slug.
plasmodial slime molds (P. Myxomycota)
Brightly pigmented slime molds. Composed of a true plasmodium.
Massive body of a plasmodial slime mold. Made of one large single cell containing scores of nuclei. Extends pseudopodia through decomposing material, engulfing food by phagocytosis. Heterotroph (absorbs organic material). Reproduces SEXUALLY.
Spore-releasing body of a plasmodial slime mold.
Plasmodium's haploid spores (released by sporangium) germinate, resulting in haploid amoeboid cells, which fertilize (sexual reproduction) and form a diploid zygote. This zygote forms the feeding plasmodium.
A.k.a. oomycetes; includes water molds, white rusts, and downy mildews. Most are decomposers or parasites. Have filaments (hyphae) that faciliate nutrient uptake. Reproduce ASEXUALLY and SEXUALLY. Can have great ecological impact.
Type of water mold that causes potato blight and kills trees.
Disease that wiped out potato population in Ireland; still remains; still haven't found way to prevent/eradicate.
protistan ancestor of animals - P. Mastigophora
Single-celled protozoans (such as zooflagellates) are protistan ancestors of animals.
protistan ancestor of fungi - P. Rhodophyta
Red algae is the protistan ancestor of fungi.
protistan ancestor of plants - P. Chlorophyta
Land plants descended from a prostitan green algae. Heterotrophic protist acquired a cyanobacterial endosymbiont; photosynthetic descendents developed into red and green algae.
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