Chapter 22

Diatom

Golden-brown alga with a cell wall in two parts, or valves; significant part of phytoplankton.

Green algae

Member of diverse group of photosynthetic protists that contains chlorophylls a and b and has other biochemical characteristics like those of plants.

Protist

Member of the kingdom Protista.

Digestive enzymes

enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body.

Phagocytosis

the ingestion of bacteria or other material by phagocytes and amoeboid protozoans.

Sporangia

(in ferns and lower plants) a receptacle in which asexual spores are formed.

Red Algae (Phylum Rhodophyta)

-Habitat: Warmer seawater, shallow and deep -Photosynthetic: chlorophyll a and phycobilin -Store nutrients as floridean starch -Life cycle stages—haploid, diploid, tetraploid -Reproduction asexual and sexual -Nonmotile spores and gametes -Body form as filaments or ribbons

Cellular Slime Molds (Phylum Acrasiomycota)

-Habitat: all obligate decomposers -Secrete digestive enzymes -Absorb nutrients from substrate -Life cycle stages—haploid and diploid -Reproduction—asexual (spores) and sexual (zygote) -Motile feeding stage (amoeboid cells), nonmotile reproductive stage (sporangia and spores)

Plasmodial Slime Molds (Phylum Myxomycota)

-Habitat: all obligate decomposers -Secrete digestive enzymes -Absorb nutrients from substrate -Life cycle stages—haploid and diploid -Reproduction—asexual (spores) and sexual (zygote) -Motile feeding stage (plasmodium), motile reproductive stage (amoeboid cells)

Sporozoans (Phylum Apicomplexa)

-Habitat: all obligate parasites -Primary and secondary hosts -Absorb nutrients from host -Life cycle stages—haploid and diploid -Reproduction—asexual and sexual -Nonmotile (cyst) or motile (infective) -Body with specialized apical organelles

Green Algae (Phylum Chlorophyta)

-Habitat: aquatic (marine and freshwater) and terrestrial -Photosynthetic: chlorophyll a and chlorophyll b -Store nutrients as starch -Life cycle stages—haploid (major phase), diploid -Reproduction asexual and sexual (conjugation) -Motile (flagellated) spores and gametes -Many different body forms -Considered to be the ancestors of the Plants -Flagellated Green Algae—Chlamydomonas -Filamentous Green Algae—Spirogyra -Multicellular Green Algae—Ulva -Colonial Green Algae—Volvox

Diatoms (Phylum Bacillariophyta)

-Habitat: aquatic—major component of phytoplankton -Photosynthetic: chlorophyll a and c -Store nutrients as lipid -Life cycle stages—haploid, diploid -Reproduction asexual and sexual -Motile adults and gametes -Body with base and lid of silica with striations -Flagellate Characteristics

Cilliates (Phylum Ciliophora)

-Habitat: aquatic—major component of zooplankton -Heterotrophic (holozoic: gullet) -Store nutrients in vessicles -Life cycle stages—haploid -Reproduction asexual and sexual (conjugation) -Motile adults (short cilia) -Body covered with many cilia

Water Mold Characteristics (Phylum Oomycota)

-Habitat: decomposers or parasites (land or water) -Secrete digestive enzymes -Absorb nutrients from substrate or from host -Life cycle stages—haploid and diploid -Reproduction—asexual (zoospores) and sexual (gametes, zygospores) -Nonmotile except for reproductive stages

Zooflagellates (Phylum Zoomastigophora)

-Habitat: freshwater -Mostly parasitic -Derive nutrients from host -Life cycle stages—haploid, diploid -Reproduction asexual and sexual -Motile adults: undulating membrane and flagellum -Body with protein strips (pellicle) with underlying microtubules

Euglenoids (Phylum Euglenophyta)

-Habitat: freshwater -Photosynthetic: chlorophyll a and b; or heterotrophic -Store nutrients as paramylon starch -Life cycle stages—haploid -Reproduction asexual -Motile adults (two flagella), eyespot -Body with protein strips (pellicle)

Dinoflagellates (Phylum Pyrrophyta)

-Habitat: marine, major component of plankton -Photosynthetic: chlorophyll a and c -Store nutrients as starch -Life cycle stages—haploid, diploid -Reproduction asexual and sexual -Motile adults (two flagella) and gametes -Body with cellulose plates

Brown Algae (Phylum Phaeophyta)

-Habitat: seawater, shallow and deep -Photosynthetic: chlorophyll a and c and fucoxanthin -Store nutrients as laminarin starch -Life cycle stages—haploid, diploid -Reproduction asexual and sexual -Motile spores and gametes -Body form as filaments, ribbons, large blades (Sea Kelp)

Paramylon

A carbohydrate resembling starch that is composed of glucose and forms the reserve foodstuff of certain algae.

Amoeboid cells

A cell, such as a leukocyte, that is able to change its form and move about like an ameba. Also called wandering cell .

Undulating membrane

A sinuous extension of the cytoplasmic membrane performing a vigorous, wavelike, and reversible movements

Laminarin

A storage polysaccharide that is found in brown algae which is purely made up of β-D-glucose residues yields from hydrolysis.

Fragmentation

Asexual reproduction takes many different forms in the protists. The simplest type of asexual reproduction involves the simple breaking off of a portion of the organism's body, which is able to establish itself as a separate individual.

Spore

Asexual reproductive or resting cell capable of developing into a new organism without fusion with another cell, in contrast to a gamete.

Amoeboid

Cell that moves and engulfs debris with pseudopods.

Trichocyst

Found in ciliates; contains long, barbed threads useful for defense and capturing prey.

Ciliate

Complex unicellular protist that moves by means of cilia and digests food in food vacuoles.

Pseudopod

Cytoplasmic extension of amoeboid protists; used for locomotion and engulfing food.

Cellular slime mold

Free-living amoeboid cells that feed on bacteria and yeasts by phagocytosis and aggregate to form a plasmodium that produces spores.

Plasmodial slime mold

Free-living mass of cytoplasm that moves by pseudopods on a forest floor or in a field, feeding on decaying plant material by phagocytosis; reproduces by spore formation.

Plankton

Freshwater and marine organisms that are suspended on or near the surface of the water; includes phytoplankton and zooplankton.

Filament

End-to-end chains of cells that form as cell division occurs in only one plane; in plants, the elongated stalk of a stamen.

Water mold

Filamentous organism having cell walls made of cellulose; typically decomposers of dead freshwater organisms, but some are parasites of aquatic r terrestrial organisms.

Euglenoid

Flagellated and flexible freshwater unicellular protist that usually contains chloroplasts and has a semi-rigid cell wall.

Sarcodines (Phylum Rhizopoda, Phylum Foraminifera, Phylum Actinopoda)

Habitat: aquatic—major component of zooplankton Heterotrophic (phagocytosis), some parasitic Store nutrients in vessicles Life cycle stages—haploid Reproduction asexual Motile adults (pseudopodia) Body naked or with shell (test) of calcium carbonate

Protozoan

Heterotrophic, unicellular protist that moves by flagella, cilia, or pseudopodia, or is immobile.

Cyst

In protists and invertebrates, resting stage that contains reproductive bodies or embryos.

Colony

Loose association of cells that remain independent for most functions.

Red algae

Marine photosynthetic protist with a notable abundance of phycobilin pigments; includes coralline algae of coral reefs.

Brown algae

Marine photosynthetic protist with a notable abundance of xanthophyll pigments; this group includes well-known seaweeds of northern rocky shores.

Haploid

Most protists spend the major portion of their life cycle in the _____ condition. During their growth and development phases the cells of their body have a single set of chromosomes.

Seaweed

Multicellular forms of red, green, and brown algae found in marine habitats.

Zooflagellate

Nonphotosynthetic protist that moves by flagella; typically zooflagellates enter into symbiotic relationships, and some are parasitic.

Holozoic

Obtaining nourishment by ingesting solid food particles.

Trypanosome

Parasitic zooflagellate that causes severe disease in human beings and domestic animals, including condition called sleeping sickness.

Phytoplankton

Part of plankton containing organisms that photosynthesize, releasing oxygen to the atmosphere and serving as food producers in aquatic ecosystems.

Zooplankton

Part of plankton containing protozoans and other types of microscopic animals.

Dinoflagellate

Photosynthetic unicellular protist with two flagella, one whiplash and the other located within a groove between protective cellulose plates; significant part of phytoplankton.

Sporic life cycle

Plants have a kind of life cycle that is characterized by having roughly equal diploid and haploid phases. This is called a ______ ______ ______ and is said to have an alternation of generations.

Colonial

Some of the species of protists have a _________ body plan. In this case the body of the organism consists of a number of cells arranged in a particular pattern, such as a long filament or a sphere. Even though the body consists of a number of cells, all of the cells usually appear very similar in structure, and may have similar functions. However, some portions and cells of the body of certain protists may be specialized to perform specific functions.

Primary producers

Some species of protists are ______ _________, meaning that they are photosynthetic and can manufacture their own food. They are the food source of other protists and other higher animal species.

Consumers

Some species of protists are ________, meaning that they ingest food materials from their environment. They function as predators of other protists, scavengers of dead organisms, decomposers of organic materials, and parasites in living hosts.

Plankton

Some species of protists are free-living and float in the upper layers of oceans and fresh-water bodies like lakes and rivers. These are called ________ and play a very important role as the basis for the food web in these aquatic environments.

Sporozoan

Spore-forming protist that has no means of locomotion and is typically a parasite with a complex life cycle having both sexual and asexual phases.

Sporangium

Structure that produces spores.

Endosymbiotic theory

Symbiogenesis, or endosymbiotic theory, is an evolutionary theory that explains the origin of eukaryotic cells from prokaryotes. It states that several key organelles of eukaryotes originated as a symbiosis between separate single-celled organisms.

Classification of the Protists

The Kingdom Protista is divided into 15 subcategories, called phyla (s. phylum). They are listed below, along with their common names: Phylum Chlorophyta—The Green Algae Phylum Rhodophyta—The Red Algae Phylum Phaeophyta—The Brown Algae Phylum Bacillariophyta—The Golden-brown Algae Phylum Pyrrophyta—The Dinoflagellates Phylum Euglenophyta—The Euglenoids Phylum Zoomastigophora—The Zooflagellates Phylum Rhizopoda—The Ameoboids Phylum Foraminifera—The Foraminiferans Phylum Actinopoda—The Radiolarians Phylum Ciliophora—The Ciliates Phylum Apicomplexa—The Sporozoans Phylum Myxomycota—The Plasmodial Slime Molds Phylum Acrasiomycota—The Cellular Slime Molds Phylum Oomycota—The Water Molds

Algae

Type of protist that carries on photosynthesis; unicellular forms are a part of phytoplankton, and multicellular forms are called seaweed.

Diploid

The human life cycle is characterized by having its major portion in the ______ phase. The only portion that is haploid is when the sex cells (sperm and eggs) are produced by meiosis. This is followed immediately by the restoration to the diploid phase during fertilization. This kind of life cycle is called the gametic (or diploid) life cycle.

Fucoxanthin

The major carotenoid pigment present, with chlorophyll, in the brown algae

Alteration of generations

The multicellular haploid plant structure is called the gametophyte, which is formed from the spore and give rise to the haploid gametes. The fluctuation between these diploid and haploid stages that occurs in plants is called the _________ __ ________.

Smaller classification of the protists

These 15 phyla can be grouped based on their mode of nutrition (autotrophs, heterotrophs), and by their mode of locomotion (flagellates, ciliates, pseudopods). The following list represents a grouping of these phyla. Each group will be discussed and characterized. Algae—green algae, red algae, brown algae Diatoms—golden-brown algae Flagellates—dinoflagellates, euglenoids, zooflagelates Sarcodines—amoeboids, foraminiferans, radiolarians Ciliates—ciliates Sporozoans—sporozoans Slime Molds—plasmodial slime molds, cellular slime molds Water Molds—water molds

Phagocytize

To ingest extracellular particles by engulfing them, as do amoeboid cells.

Euglenoids

a flagellated single-celled organism of a group that comprises euglena and its relatives.

Vesicles

a fluid- or air-filled cavity or sac, in particular.

Plasmodium

a form within the life cycle of some simple organisms such as slime molds, typically consisting of a mass of naked protoplasm containing many nuclei.

Silica

a hard, unreactive, colorless compound that occurs as the mineral quartz and as a principal constituent of sandstone and other rocks.

Microtubules

a microscopic tubular structure present in numbers in the cytoplasm of cells, sometimes aggregating to form more complex structures.

Obligate parasites

a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce.

Eyespot

a simple visual organ found in many invertebrates, consisting of pigment cells covering a sensory nerve termination.

Foraminiferan

a single-celled planktonic animal with a perforated chalky shell through which slender protrusions of protoplasm extend. Most kinds are marine, and when they die, their shells form thick ocean-floor sediments.

Zoospores

a spore of certain algae, fungi, and protozoans, capable of swimming by means of a flagellum.

Pseudopodia

a temporary protrusion of the surface of an amoeboid cell for movement and feeding.

Pellicle

a thin layer supporting the cell membrane in various protozoa.

Calcium carbonate

a white, insoluble solid occurring naturally as chalk, limestone, marble, and calcite, and forming mollusk shells and stony corals.

Autotrophs

able to manufacture their own food from sunlight through the process of photosynthesis. Examples of autotrophic protists include the algae and the euglenoids.

Decomposers

an organism, especially a soil bacterium, fungus, or invertebrate, that decomposes organic material.

Holozoic

animal-like in mode of obtaining nourishment, lacking photosynthetic capacity; denoting certain protozoans, in distinction to others that are holophytic.

Lipids

any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents. They include many natural oils, waxes, and steroids.

Protists

any of a diverse taxonomic group and especially a kingdom (Protista syn. Protoctista) of eukaryotic organisms that are unicellular and sometimes colonial or less often multicellular and that typically include the protozoans, most algae, and often some fungi (as slime molds)

Phycobilin

any of a group of red or blue photosynthetic pigments present in some algae.

Heterotrophs

are required to ingest their food materials from their environment. Examples of heterotrophic protists include those that are parasites and predators.

Flagellates

characterized by having a long, whip-like structure that is used for propulsion through a watery environment. Some have anterior flagella that they use to pull themselves, while others have posterior flagella that are used to push themselves forward. The Flagellates can be divided into three phyla.

Slime molds

characterized by the ability to secrete digestive enzymes to the outside of their bodies as they crawl over their food source. They are major decomposers of plant materials. The Slime Molds can be divided into two phyla.