Chapter 28 - Protists Flashcards
Protist -
eukaryotes that are not plants, animals, or fungi.
Protists are __________
Unicellular
Contractile vacuoles -
pump excess water from the protistan cell
Ocelloid -
eye-like organelle with components resembling the lens and retina in the eyes of vertebrates and some other animals
Mixotrophs -
combine photosynthesis and heterotrophic nutrition
Gram-negative bacteria -
have two cell membranes, an inner plasma membrane and an outer membrane that is part of the cell wall
Secondary endosymbiosis -
organism is ingested in the food vacuoles of heterotrophic eukaryotes and becomes an endosymbiont itself
Excavata (the excavates) -
one of the four main groups of protists: a clade that was originally proposed based on morphological studies of the cytoskeleton, members of this diverse group have an “excavated” feeding groove on one side of the cell body.
Diplomonads -
one of the four main groups of protists: have reduced mitochondria called mitosomes so they get the energy they need from anaerobic biochemical pathways. Many are parasites
Mitosomes -
organelles lack functional electron transport chains and hence cannot use oxygen to help extract energy from carbohydrates and other organic molecules
Parabasalids -
one of the four main groups of protists: also have reduced mitochondria; called hydrogenosomes
Hydrogenosomes -
these organelles generate some energy anaerobically, releasing hydrogen gas as a by-product
Euglenozoans -
one of the four main groups of protists: a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites. The main morphological feature that distinguishes protists in this clade is the presence of a rod with either a spiral or a crystalline structure inside each of their flagella
kinetoplastids -
have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast. These protists include species that feed on prokaryotes in freshwater, marine, and moist terrestrial ecosystems, as well as species that parasitize animals, plants, and other protists
“bait-and-switch” defense -
the urface of a trypanosome is coated with millions of copies of a single protein. However, before the host’s immune system can recognize the protein and mount an attack, new generations of the parasite switch to another surface protein with a different molecular structure
A euglenid -
has a pocket at one end of the cell from which one or two flagella emerge
SAR
supergroup, also just SAR or Harosa, is a clade of eukaryotic organisms that includes stramenopiles, alveolates, and Rhizaria. The name is an acronym derived from the first letters of each of these clades
The stramenopiles -
one major subgroup of SAR that includes some of the most important photosynthetic organisms on the planet and is grouped due to their flagellums
In most stramenopiles, this “______” flagellum is paired with a shorter “_______” (nonhairy) flagellum
hairy; smooth
The three groups of stramenopiles:
diatoms, oomycetes, and brown algae
Diatoms -
unicellular algae that have a unique glass-like wall made of silicon dioxide embedded in an organic matrix
estimated ________ living species, _______ are a highly diverse group of protists
100,000; diatoms
Brown algae -
the largest and most complex algae, all are multicellular, and most are marine. Especially common along temperate coasts that have cold-water currents. They owe their characteristic brown or olive color to the carotenoids in their plastids
Holdfast -
a rootlike specialized structure which anchors the alga
Stipe -
specialized structure that provides support
Blades -
specialized structure that are leaflike
Gas-filled, bubble-shaped floats -
adaptations that enable their main photosynthetic surfaces (the leaflike blades) to be near the water surface
Alternation of generations -
the alternation of multicellular haploid and diploid forms, applies only to life cycles in which both haploid and diploid stages are multicellular
Zoospores -
haploid spores that move by means of flagella
Sporophyte -
the diploid individual that produces spores
Zoospores -
the spores that are haploid and move by means of flagella
Heteromorphic generations -
the sporophytes and gametophytes are structurally different
isomorphic generations -
in which the sporophytes and gametophytes look similar to each other, although they differ in chromosome number
Oomycetes -
include the water molds, the white rusts, and the downy mildews. Based on their morphology, these organisms were previously classified as fungi
oomycetes typically have cell walls made of cellulose, don’t have plastids, no photosynthesis, typically decomposers or parasites
Alveolates -
subgroup of SAR; have membrane-enclosed sacs (alveoli) just under the plasma membrane
Three alveolate clades:
the dinoflagellates, the apicomplexans, and the ciliates
The dinoflagellates -
group of flagellates; The cells of many are reinforced by cellulose plates that house two flagella, one of which causes them to spin as they move through the waters of their marine and freshwater communities
The apicomplexans
a group of parasites; nearly all are parasites of animals—and virtually all animal species examined so far are attacked by these parasites
The ciliates
a group of protists that move using cilia; a large and varied group of protists named for their use of cilia to move and feed, most are predators, typically of bacteria or of other protists.
Conjugation -
genetic variation resulting from a sexual process in which two individuals exchange haploid micronuclei but do not reproduce
Rhizarians -
subgroup of SAR, many species in this group are amoebas
Amoebas -
protists that move and feed by means of pseudopodia, extensions that may bulge from almost anywhere on the cell surface
Pseudopodia -
extensions that may bulge from almost anywhere on the cell surface
Three groups of rhizarians:
radiolarians, forams, and cercozoans
Radiolarians -
protists that have delicate, intricately symmetrical internal skeletons that are generally made of silica, and the pseudopodia of these mostly marine protists radiate from the central body reinforced by bundles of microtubules
Foraminiferans or forams -
protists named for their porous shells called tests that consist of a single piece of organic material that typically is hardened with calcium carbonate, found in both the ocean and freshwater
Cercozoans -
a large group of amoeboid and flagellated protists that feed using threadlike pseudopodia, common inhabitants of marine, freshwater, and soil ecosystems.
Archaeplastida -
together, red algae, green algae, and plants make up our third eukaryotic supergroup which is a monophyletic group that descended from the ancient protist that engulfed a cyanobacterium
Red algae -
reddish, reproduce sexually, and are mostly multicellular, owing to the photosynthetic pigment phycoerythrin, which masks the green of chlorophyll
Green algae -
containing green chloroplasts similar in structure and pigment composition to those chloroplasts of plants. Molecular systematics and cellular morphology leave little doubt that plants are closely related
Green algae two main groups:
the charophytes and the chlorophytes
Unikonta -
an extremely diverse supergroup of eukaryotes that includes animals, fungi, and some protists
The two major clades of unikonts:
the amoebozoans (tubulinids and close protist relatives) and the opisthokonts (animals, fungi, and closely related protist groups)
Amoebozoan clade -
includes many species of amoebas that have lobe- or tube-shaped pseudopodia rather than the threadlike pseudopodia found in rhizarians. Includes tubulinids, slime molds, and entamoebas
Tubulinids -
constitute a large and varied group of amoebozoans that have lobe- or tube-shaped pseudopodia. These unicellular protists are ubiquitous in soil as well as freshwater and marine environments.
Slime molds, or mycetozoans -
produce fruiting bodies that aid in spore dispersal, evolutionary convergence based similarity to fungi
Slime molds two main branches:
plasmodial slime molds and cellular slime molds.
Plasmodium -
not multicellular; it is a single mass of cytoplasm that is undivided by plasma membranes and that contains many nuclei. This “supercell” is the product of mitotic nuclear divisions that are not followed by cytokinesis
Cellular slime molds
feeding stage of these organisms consists of solitary cells that function individually, but when food is depleted, the cells form a slug-like aggregate that functions as a unit
Entamoeba -
symbiotic parasites, infecting all classes of vertebrate animals as well as some invertebrates
Producers -
organisms that use energy from light (or in some prokaryotes, inorganic chemicals) to convert to organic compounds
