Term
| alternation of generations |
|
Definition
| The succession of multicellular haploid and diploid phases in some sexually reproducing organisms, notably plants. |
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Term
| alveolates (Alveolata) [7] |
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Definition
| Unicellular eukaryotes with a layer of flattened vesicles (alveoli) supporting the plasma membrane. Major alveolate groups include the dinoflagellates [49], apicomplexans [50], and ciliates [51]. |
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Term
| amoebozoans (Amoebozoa) [76] |
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Definition
| A group of eukaryotes [4] that use lobe-shaped pseudopods for locomotion and to engulf food. Major amoebozoan groups include the loboseans, plasmodial slime molds, and cellular slime molds. |
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Term
| anisogamy (an eye sog´ a mee) [Gk. aniso: unequal + gamos: marriage] |
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Definition
| The existence of two dissimilar gametes (egg and sperm). |
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Term
| apicomplexans (Apicomplexa) [50] Parasitic alveolates [7] |
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Definition
| characterized by the possession of an apical complex at some stage in the life cycle. |
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Term
| brown algae (Phaeophyta) [46] |
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Definition
| Multicellular, almost exclusively marine stramenopiles [6] generally containing the pigment fucoxanthin as well as chlorophylls a and c in their chloroplasts. |
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Term
| cellular slime molds (Dictyostelida) |
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Definition
| Amoebozoans [76] in which individual amoebas aggregate under stress to form a multicellular pseudoplasmodium. |
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Term
| cercozoans (Cercozoa) [74] |
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Definition
| Unicellular eukaryotes [4] that feed by means of threadlike pseudopods. Together with foraminiferans [73] and radiolarians [75], the cercozoans comprise the group Rhizaria [15]. |
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Term
| charophytes (Charales) [64] |
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Definition
| Multicellular green algae with branching, apical growth and plasmodesmata between adjacent cells. The closest living relatives of the land plants [10], they retain the egg in the parent organism. |
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Term
| chlorophytes (Chlorophyta) [65] |
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Definition
| The most abundant and diverse group of green algae, including freshwater, marine, and terrestrial forms; some are unicellular, others colonial, and still others multicellular. Chlorophytes use chlorophylls a and c in their photosynthesis. |
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Term
| choanoflagellates (Choanozoa) [82] |
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Definition
| Unicellular eukaryotes [4] with a single flagellum surrounded by a collar. Most are sessile, some are colonial. The closest living relatives of the animals [19] |
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Term
| ciliates (Ciliophora) [51] |
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Definition
| Alveolates [7] with numerous cilia and two types of nuclei (micronuclei and macronuclei). |
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Term
| coenocyte (seen´ a sight) [Gk. koinos: common + kytos: container] |
|
Definition
| A "cell" enclosed by a single plasma membrane but containing many nuclei. |
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Term
| conjugation (kon ju gay´ shun) [L. conjugare: yoke together] |
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Definition
| The close approximation of two cells during which they exchange genetic material, as in Paramecium and other ciliates, or during which DNA passes from one to the other, as in bacteria. |
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|
Term
| diatoms (Bacillariophyta) [47] |
|
Definition
| Unicellular, photosynthetic stramenopiles [6] with glassy cell walls in two parts. |
|
|
Term
| dinoflagellates (Dinoflagellata) [49] |
|
Definition
| A group of alveolates [7] usually possessing two flagella, one in an equatorial groove and the other in a longitudinal groove; many are photosynthetic. |
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|
Term
| diplomonads (Diplomonadida) [72] |
|
Definition
| A group of eukaryotes [4] lacking mitochondria; most have two nuclei, each with four associated flagella. |
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|
Term
|
Definition
| A type of life cycle in which gametes are the only haploid cells and mitosis occurs only in diploid cells. (Contrast with haplontic.) |
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Term
| endosymbiosis [Gk. endo: within + sym: together + bios: life] |
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Definition
| Two species living together, with one living inside the body (or even the cells) of the other. |
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|
Term
| euglenids (Euglenida) [69] |
|
Definition
| Flagellate excavates characterized by a pellicle composed of spiraling strips of protein under the plasma membrane; the mitochondria have disk-shaped cristae. Some are photosynthetic. |
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|
Term
| excavates (Excavata) [14] |
|
Definition
| Diverse group of unicellular, flagellate eukaryotes, many of which possess a feeding groove; some lack mitochondria. |
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|
Term
|
Definition
| Membrane enclosed structure formed by phagocytosis in which engulfed food particles are digested by the action of lysosomal enzymes. |
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|
Term
| foraminiferans (Foraminifera) [73] |
|
Definition
| Amoeboid organisms with fine, branched pseudopods that form a food-trapping net. Most produce external shells of calcium carbonate. |
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Term
| gametophyte (ga meet´ oh fyte) |
|
Definition
| In plants and photosynthetic protists with alternation of generations, the multicellular haploid phase that produces the gametes. (Contrast with sporophyte.) |
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Term
| glaucophytes (Glaucophyta) [67] |
|
Definition
| Unicellular freshwater algae with chloroplasts containing traces of peptidoglycan, the characteristic cell wall material of bacteria. |
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|
Term
|
Definition
| A type of life cycle in which the zygote is the only diploid cell and mitosis occurs only in haploid cells. (Contrast with diplontic.) |
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Term
| haptophytes (Haptophyta) [45] |
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Definition
| Unicellular, photosynthetic stramenopiles [6] with two slightly unequal, smooth flagella. Abundant as phytoplankton, some form marine algal blooms. |
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Term
| heteromorphic (het´ er oh more´ fik) [Gk. heteros: different + morphe: form] |
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Definition
| Having a different form or appearance, as two heteromorphic life stages of a plant. (Contrast with isomorphic.) |
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|
Term
|
Definition
| Describes male and female gametes that are morphologically identical. |
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|
Term
| isomorphic (eye so more´ fik) [Gk. isos: equal + morphe: form] |
|
Definition
| Having the same form or appearance, as when the haploid and diploid life stages of an organism appear identical. (Contrast with heteromorphic.) |
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|
Term
| kinetoplastids (Kinetoplastida) [68] |
|
Definition
| Unicellular, flagellate organisms characterized by the presence in their single mitochondrion of a kinetoplast (a structure containing multiple, circular DNA molecules). |
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|
Term
|
Definition
| A group of unicellular amoebozoans [76]; includes the most familiar amoebas (e.g., Amoeba proteus). |
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|
Term
| oomycetes (Oomycota) [48] |
|
Definition
| Water molds and relatives; absorptive heterotrophs with nutrient-absorbing, filamentous hyphae. |
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|
Term
| opisthokonts (Opisthokonta) [18] |
|
Definition
| A group of unikonts [16] in which the flagellum on motile cells, if present, is posterior. The opisthokonts include the fungi [17], animals [19], and choanoflagellates [82]. |
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|
Term
| parabasalids (Parabasalia) [71] |
|
Definition
| A group of unicellular eukaryotes [4] that lack mitochondria; they possess flagella in clusters near the anterior of the cell. |
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|
Term
|
Definition
| Free-floating small organisms inhabiting the surface waters of lakes and oceans. Photosynthetic members of the plankton are referred to as phytoplankton. |
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|
Term
|
Definition
| The most broadly defined plant group. In most parts of this book, we use the word "plant" as synonymous with "land plant" [10], a more restrictive definition. |
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|
Term
| plasmodial slime molds (Myxogastrida) |
|
Definition
| Amoebozoans [76] that in their feeding stage consist of a coenocyte called a plasmodium. |
|
|
Term
|
Definition
| This term of convenience does not describe a monophyletic group but is used to encompass a large number of distinct and distantly related groups of eukaryotes, many but far from all of which are microbial and unicellular. Essentially a "catch-all" term for any eukaryote group not contained within the land plants [10], fungi [17], or animals [19]. |
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|
Term
| pseudopod (soo´ do pod) [Gk. pseudes: false + podos: foot] |
|
Definition
| A temporary, soft extension of the cell body that is used in location, attachment to surfaces, or engulfing particles. |
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|
Term
| radiolarians (Radiolaria) [75] |
|
Definition
| Amoeboid organisms with needle-like pseudopods supported by microtubules. Most have glassy internal skeletons. |
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|
Term
| red algae (Rhodophyta) [66] |
|
Definition
| Mostly multicellular, marine algae characterized by the presence of phycoerythrin in their chloroplasts. |
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|
Term
|
Definition
| Mostly amoeboid unicellular eukaryotes with pseudopods, many with external or internal shells. Includes the foraminiferans [73], cercozoans [74], and radiolarians [75]. |
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|
Term
| saprobe [Gk. sapros: rotten] |
|
Definition
| An organism (usually a bacterium or fungus) that obtains its carbon and energy directly from dead organic matter. |
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|
Term
|
Definition
| Specialized cells of the diploid sporophyte that will divide by meiosis to produce four haploid spores. Germination of these spores produces the haploid gametophyte. |
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|
Term
| sporophyte (spor´ o fyte) [Gk. spora: seed + phyton: plant] |
|
Definition
| In plants and protists with alternation of generations, the diploid phase that produces the spores. (Contrast with gametophyte.) |
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|
Term
| stramenopiles (Heterokonta or Stramenopila) [6] |
|
Definition
| Organisms having, at some stage in their life cycle, two unequal flagella, the longer possessing rows of tubular hairs. Chloroplasts, when present, surrounded by four membranes. Major stramenopile groups include the brown algae [46], diatoms [47], and oomycetes [48]. |
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|
Term
|
Definition
| A group of eukaryotes [4] whose motile cells possess a single flagellum. Major unikont groups include the amoebozoans [76], fungi [17], and animals [19]. |
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|
Term
| vacuole (vac´ yew ole) [Fr.: small vacuum] |
|
Definition
| A liquid-filled, membrane-enclosed compartment in cytoplasm; may function as digestive chambers, storage chambers, waste bins. |
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