Med micro chapter 12 pages 337-346
Protozoa
------- are unicellular, eukaryotic organisms. Among the protozoa are many variations on this cell structure, as we shall see. Protozoa inhabit water and soil. The feeding and growing stage, or trophozoite, feeds upon bacteria and small particulate nutrients
Dinoflagellates
---------- are unicellular algae collectively called plankton, or free-floating organisms (Figure 12.15). Their rigid structure is due to cellulose embedded in the plasma membrane.
Vegetative hyphae
---------- produce motile zoospores as well as specialized sex hyphae (see Figure 12.16). All of the U.S. strains were one mating type ("sex") called A1. In the 1990s, the other mating type, A2, was identified in the United States. When in close proximity, A1 and A2 will differentiate to produce haploid gametes that can mate to form a zygote. When the zygote germinates, the resulting alga will have genes from both parents.
Phytophthora
------------ was introduced into the United States in the 1990s and caused widespread damage to fruit and vegetable crops. When California oak trees suddenly started dying in 1995, University of California scientists identified the cause of this "sudden oak death" to be a new species, P. ramorum. P. ramorum also infects redwood tree
Carrageenan and agar
-------------- can be a thickening ingredient in evaporated milk, ice cream, and pharmaceutical agents
gamete
A male or female reproductive cell.
identification of cysts in feces.
A parasite without mitochondria is Giardia intestinalis (JAR-dē-ah in'tes-tin-AL-is), sometimes called G. lamblia or G. duodenalis. The parasite (Figure 12.18a and Figure 25.16a) is found in the small intestine of humans and other mammals. It is excreted in the feces as a cyst (Figure 25.16b) and survives in the environment before being ingested by the next host. Diagnosis of giardiasis, the disease caused by G. intestinalis, is often based on the
algin
A sodium salt of mannuronic acid (C6H8O6); found in brown algae.
rRNA
Algae are classified according to their -----sequences, structures, pigments, and other qualities (see Table 12.3). Following are descriptions of some phyla of algae
True
Algae are familiar as the large brown kelp in coastal waters, the green scum in a puddle, and the green stains on soil or on rocks. A few algae are responsible for food poisonings. Some algae are unicellular; others form chains of cells (are filamentous); and a few have thalli.
aquatic
Algae are mostly -----, although some are found in soil or on trees when sufficient moisture is available there.
sexually
Algae can also reproduce ------ (Figure 12.13). In some species, asexual reproduction may occur for several generations and then, under different conditions, the same species reproduce sexually. Other species alternate generations so that the offspring resulting from sexual reproduction reproduce asexually, and the next generation then reproduces sexually.
photosynthetic
Algae is a common name that includes several phyla (Table 12.3). Most algae are --------; however, the oomycotes, or fungal-like algae, are chemoheterotrophs
photoautotrophs
Algae" is not a taxonomic group; it is a way to describe ------- that lack the roots and stems of plants. Historically they were considered plants, but they lack the embryos of true plants.
rubber tires and hand lotion
Algin is also used in the production of a wide variety of nonfood goods, including--------
asexually
All algae can reproduce -------. Multicellular algae with thalli and filamentous forms can fragment; each piece is capable of forming a new thallus or filament. When a unicellular alga divides, its nucleus divides (mitosis), and the two nuclei move to opposite parts of the cell. The cell then divides into two complete cells (cytokinesis).
cytostome.
All protozoa live in areas with a large supply of water. Some protozoa transport food across the plasma membrane. However, some have a protective covering, or pellicle, and thus require specialized structures to take in food. Ciliates take in food by waving their cilia toward a mouthlike opening called a
phagocytizing it.
Amebae engulf food by surrounding it with pseudopods and ------------
algal bloom
An abundant growth of microscopic algae producing visible colonies in nature
carrageenan
Another gelatinous material, ------------, comes from a species of red algae commonly called Irish moss.
Toilet facilities or towels.
Another human parasite that lacks mitochondria is Trichomonas vaginalis (TRIK-ō-mō-nas vaj-i-NA-lis), shown in Figure 12.18b and Figure 26.16. Like some other flagellates, T. vaginalis has an undulating membrane, which consists of a membrane bordered by a flagellum. T. vaginalis does not have a cyst stage and must be transferred from host to host quickly before desiccation occurs. T. vaginalis is found in the vagina and in the male urinary tract. It is usually transmitted by sexual intercourse but can also be transmitted by _____________.
It is easy to see how humans are chemoheterotrophs! We eat food every day. That food is made from animals, plants, and other organisms. We break down the organic chemicals from their cells to both obtain our own energy, and building materials for our own bodies.
Are humans Chemoheterotrophs?
zoospores
Asexually, the oomycotes resemble the zygomycete fungi in that they produce spores in a sporangium (spore sac). However, oomycote spores, called ----------- (Figure 12.16, top right), have two flagella; fungi do not have flagella
True
Blooms of dinoflagellates are responsible for seasonal red tides. Blooms of a certain few species indicate that the water in which they grow is polluted because these algae thrive in high concentrations of organic materials that exist in sewage or industrial wastes. When algae die, the decomposition of the large numbers of cells associated with an algal bloom depletes the level of dissolved oxygen in the water. (This phenomenon is discussed in Chapter 27.)
diatom identification
Diatoms (Figure 12.14) are unicellular or filamentous algae with complex cell walls that consist of pectin and a layer of silica. The two parts of the wall fit together like the halves of a Petri dish. The distinctive patterns of the walls are a useful tool in ---------. Diatoms store energy captured through photosynthesis in the form of oil.
Stramenopila
Diatoms, dinoflagellates, and water molds are grouped into the Kingdom
paralytic shellfish poisoning (PSP
Dinoflagellates in the genus Alexandrium (a'leks-AN-drē-um) produce neurotoxins (called saxitoxins) that cause ---------- The toxin is concentrated when large numbers of dinoflagellates are eaten by mollusks, such as mussels or clams. Humans who eat these mollusks develop PSP
cool temperate water
Generally, algae are found in ------- although the large floating mats of the brown alga Sargassum (sar-GAS-sum) are found in the subtropical Sargasso Sea, and some species of brown algae grow in antarctic waters.
Algae is photosynthetic and eukaryotic
How do algae differ from bacteria? From fungi?
algae are photosynthetic
How do algae differ from fungi?
Fermentation
How does Giardia obtain energy without mitochondria?
True
In Australia, P. cinnamoni has infected about 20% of one species of Eucalyptus tree.
Phytophthora infestans (fĪ-TOF-thor-ah in-FES-tans)
In Ireland during the mid-1800s, 1 million people died when the country's potato crop failed. The alga that caused the great potato blight, ------------, was one of the first microorganisms to be associated with a disease
vacuoles, anal pore
In all protozoa, digestion takes place in membrane-enclosed ---------, and waste may be eliminated through the plasma membrane or through a specialized -------.
Diatoms
Is this oomycote more closely related to Penicillium or to diatoms?
red tide
Large concentrations of Alexandrium give the ocean a deep red color, from which the name ------- originates
diatoms pectin and silica cause domoic acid intoxication dinoflagellates cellulose in membrane paralytic shellfish poisoning (PSP) oomycotes cellulose Phytophthora infestans - microorganism with disease caused potato famine!
List the cell wall composition and diseases caused by the following algae: diatoms, dinoflagellates, oomycotes.
carbohydrate
Many unicellular algae are symbionts in animals. The giant clam Tridacna (trĪ-DAK-nah) has evolved special organs that host dinoflagellates. As the clam sits in shallow water, the algae proliferate in these organs when they are exposed to the sun. The algae release glycerol into the clam's bloodstream, thus supplying the clam's ------- requirement. In addition, evidence suggests that the clam gets essential proteins by phagocytizing old algae.
ciguatera
Mollusks should not be harvested for consumption during a red tide. A disease called ------ occurs when the dinoflagellate Gambierdiscus toxicus (GAM-bē-er-dis-kus TOKS-i-kus) passes up the food chain and is concentrated in large fish
red algae
Most ------- have delicately branched thalli and can live at greater ocean depths than other algae
ocean.
Most algae are found in the ------ Their locations depend on the availability of appropriate nutrients, wavelengths of light, and surfaces on which they can grow. Probable locations for representative algae are shown in Figure 12.12a.
microscopic
Most green algae are -------, although they may be either unicellular or multicellular
decomposers.
Most water molds, or Oomycota, are ---------. They form the cottony masses on dead algae and animals, usually in fresh water
petroleum
Much of the world's --------- was formed from diatoms and other planktonic organisms that lived several million years ago. When such organisms died and were buried by sediments, the organic molecules they contained did not decompose to be returned to the carbon cycle as CO2. Heat and pressure resulting from the Earth's geologic movements altered the oil stored in the cells, as well as the cell membranes. Oxygen and other elements were eliminated, leaving a residue of hydrocarbons in the form of petroleum and natural gas deposits.
photic (light) zone of bodies of water.
Photosynthetic algae are found throughout the ----------
DNA data and morphology
Protozoa are a large and diverse group. Current schemes of classifying protozoan species into phyla are based on ------------------. As more information is obtained, some of the phyla discussed here may be grouped to form kingdoms.
True
Protozoa are mostly aerobic heterotrophs, although many intestinal protozoa are capable of anaerobic growth. Two chlorophyll-containing groups, dinoflagellates and euglenoids, are often studied with algae.
fission, budding, or schizogony
Protozoa reproduce asexually by -------------
algal blooms.
Seasonal changes in nutrients, light, and temperature cause fluctuations in algal populations; periodic increases in numbers of planktonic algae are called
Life Cycle
Sexual reproduction has been observed in some protozoa. The ciliates, such as Paramecium, reproduce sexually by conjugation (Figure 12.17), which is very different from the bacterial process of the same name (see Figure 8.30). During protozoan conjugation, two cells fuse, and a haploid nucleus (the micronucleus) from each cell migrates to the other cell. This haploid micronucleus fuses with the haploid micronucleus within the cell. The parent cells separate, each now a fertilized cell. When the cells later divide, they produce daughter cells with recombined DNA. Some protozoa produce gametes (gametocytes), which are haploid sex cells. During reproduction, two gametes fuse to form a diploid zygote.
Feeding Grooves
Single-celled eukaryotes with a feeding groove in the cytoskeleton have been placed in the Excavata. Most are spindle-shaped and possess flagella (Figure 12.18). This superkingdom includes two phyla that lack mitochondria and the phylum Euglen
neurotoxins
Some dinoflagellates produce----------. In the last 20 years, a worldwide increase in toxic marine algae has killed millions of fish, hundreds of marine mammals, and even some humans
Green algae
Some filamentous kinds form grass-green scum in ponds.
True
Some protozoa are part of the normal microbiota of animals. See Exploring the Microbiome in Chapter 4, page 94. Researchers at the U.S. Department of Agriculture are studying an apicomplexan protozoan that reduces egg production by fire ants. Fire ants cause millions of dollars in agricultural damage each year and can cause painful stings. Of the nearly 20,000 species of protozoa, relatively few cause human disease. Those few, however, have significant health and economic impact. Malaria is the fourth leading cause of death in children in Africa.
agar
The ----- used in microbiological media is extracted from many red algae.
brown algae
The -------, or kelp, are macroscopic; some reach lengths of 50 m (see Figure 12.12b). Most brown algae are found in coastal waters. Brown algae have a phenomenal growth rate. Some grow at rates exceeding 20 cm per day and therefore can be harvested regularly
red pigments
The -------- enable red algae to absorb the blue light that penetrates deepest into the ocean
thalli
The -------- of a few red algae form crustlike coatings on rocks and shells
True
The USDA inspects imported plants for white rust and other parasites. Often travelers, or even commercial plant importers, do not realize that one little blossom or seedling could carry a pest that is capable of causing millions of dollars' worth of damage to U.S. agriculture.
pseudopods
The amebae move by extending blunt, lobelike projections of the cytoplasm called ------- (Figure 12.19a). Any number of pseudopods can flow from one side of the ameba, and the rest of the cell will flow toward the pseudopods
True
The body of a multicellular alga is called a thallus. Thalli of the larger multicellular algae, those commonly called seaweeds, consist of branched holdfasts (which anchor the alga to a rock), stemlike and often hollow stipes, and leaflike blades (Figure 12.12b)
photosynthesis
The cells covering the thallus can carry out ----------
DNA and structural data are collected
The classification of algae is currently in flux as -------- Algae are currently grouped into super clades—see Table 12.3.
an oocyst
The cyst formed by members of the phylum Apicomplexa is called --------. It is a reproductive structure in which new cells are produced asexually.
domoic acid toxicosis
The first reported outbreak of a neurological disease caused by diatoms was reported in 1987 in Canada. Affected people ate mussels that had been feeding on diatoms. The diatoms produced domoic acid, a toxin that was concentrated in the mussels. Symptoms occurred within 24 hours of eating and included diarrhea and memory loss. The fatality rate was less than 4%. Subsequent outbreaks showed that in some cases, the brain damage may be permanent. Since 1991, hundreds of marine birds and sea lions have died from the same ----------- in California.
microscopic examination.
The identification of unicellular and filamentous algae requires
cytostome
The mouthlike opening in some protozoa.
Schizogony
The process of multiple fission, in which one organism divides to produce many daughter cells.
Characteristics of Protozoa
The term protozoa means "first animals," meant to describe animal-like nutrition. However, protozoa are quite different from animals—a few are photosynthetic, and many have complex life cycles that enable them to get from one host to the next. Protozoa are now classified into the same super clades as algae, based on DNA analyses
pneumatocyst
The thallus lacks the conductive tissue (xylem and phloem) characteristic of vascular plants; algae absorb nutrients from the water over their entire surface. The stipe is not lignified or woody, so it does not offer the support of a plant's stem; instead, the surrounding water supports the algal thallus; some algae are also buoyed by a floating, gas-filled bladder called a -------
planktonic algae.
The top few meters of any body of water contain planktonic algae. As 75% of the Earth is covered with water, it is estimated that 80% of the Earth's O2 is produced by -------.
conjugation
The transfer of genetic material from one cell to another involving cell-to-cell contact.
fungi
Their cellulose cell walls always raised the question about their relationship to algae, and recent DNA analyses have confirmed that oomycotes are more closely related to diatoms and dinoflagellates than to ----------
Euglenozoa
Two groups of flagellated cells are included in the --------- based on common rRNA sequences, disk-shaped mitochondria, and absence of sexual reproduction.
True
Under certain adverse conditions, some protozoa produce a protective capsule called a cyst. A cyst permits the organism to survive when food, moisture, or oxygen are lacking, when temperatures are not suitable, or when toxic chemicals are present. A cyst also enables a parasitic species to survive outside a host. This is important because parasitic protozoa may have to be excreted from one host in order to get to a new host
True
Unusual algal habitats include the hair of both the sedentary South American sloth and the polar bear Water is necessary for physical support, reproduction, and the diffusion of nutrients.
Domoic acid intoxication
What human disease is caused by diatoms?
In the past few decades, extensive studies have been devoted to the toxicology and pharmacology of dinoflagellate toxins [11], and five major seafood poisoning syndromes caused by toxins have been identified from the dinoflagellates (Table 1): paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP),
What human diseases are caused by dinoflagellates?
Significance. Algae are the ultimate source of food and energy for other organisms in aquatic ecosystems. As primary producers, algae form the basis of the aquatic food web.
What is the primary role of algae in the ecosystem?
True
When fish swim through large numbers of the dinoflagellate Karenia brevis (kar-en-Ē-ah BREV-is), the algae trapped in the gills of the fish release a neurotoxin that stops the fish from breathing
Algin
a thickener used in many foods (such as ice cream and cake decorations), is extracted from their cell walls (brown algae)
Algae
are an important part of any aquatic food chain because they fix carbon dioxide into organic molecules that can be consumed by chemoheterotrophs. Using the energy produced in photophosphorylation, algae convert carbon dioxide in the atmosphere into carbohydrates. Molecular oxygen (O2) is a by-product of their photosynthesis
Green algae
are believed to have given rise to terrestrial plants.
Euglenoids
are photoautotrophs (Figure 12.18c). Euglenoids have a semirigid plasma membrane called a pellicle, and they move by means of a flagellum at the anterior end. Most euglenoids also have a red eyespot at the anterior end. This carotenoid-containing organelle senses light and directs the cell in the appropriate direction by using a preemergent flagellum. Some euglenoids are facultative chemoheterotrophs. In the dark, they ingest organic matter through a cytostome. Euglenoids are frequently studied with algae because they can photosynthesize.
Algae
are relatively simple eukaryotic photoautotrophs that lack the tissues (roots, stem, and leaves) of plants
The hemoflagellates (blood parasites)
are transmitted by the bites of blood-feeding insects and are found in the circulatory system of the bitten host. To survive in this viscous fluid, hemoflagellates usually have long, slender bodies and an undulating membrane. The genus Trypanosoma (TRI-pa-nō-sō-mah) includes the species that causes African sleeping sickness, T. brucei (BROOS-e-ē), which is transmitted by the tsetse fly. T. cruzi (KROOZ-ē; see Figure 23.22), the causative agent of Chagas disease, is transmitted by the "kissing bug," so named because it bites on the face (see Figure 12.32d). After entering the insect, the trypanosome rapidly multiplies by schizogony. If the insect then defecates while biting a human, it can release trypanosomes that can contaminate the bite wound.
Green algae
have cellulose cell walls, contain chlorophyll a and b, and store starch, as plants do (see Figure 12.13a)
Laminaria japonica
he brown alga -------------- is used to induce vaginal dilation before surgical entry into the uterus through the vagina
Ciguatera
is endemic (constantly present) in the south Pacific Ocean and the Caribbean Sea. An emerging disease associated with heterotrophic Pfiesteria (fē-STEER-ē-ah) is responsible for periodic massive fish deaths along the Atlantic Coast.
Schizogony
is multiple fission; the nucleus undergoes multiple divisions before the cell divides. After many nuclei are formed, a small portion of cytoplasm concentrates around each nucleus, and then the single cell separates into daughter cells.
Chlorophyll
l a (a light-trapping pigment) and accessory pigments involved in photosynthesis are responsible for the distinctive colors of many algae
Gracilaria species (algae)
which grow in the Pacific Ocean, are used by humans for food. However, some members of this genus can produce a lethal toxin.
