1. Ciliates are single cells that propel themselves with fine cilia.

2. Flagellates move by means of long flagella, often only two but sometimes many.

3. Amoebas are often quite shapeless and move by extending rounded pseudopods, which they also use to engulf food.

1. Molds are osmiotrophs, generally saprobes or saprophytes, which decompose the detritus of an ecosystem and absorb nutrients from the water and soil; or they are parasites, which absorb nutrients from the cells of other organisms.

2. Saprobes produce their own extracellular digestive enzymes and pick up the released monomers, or they rely on the digestive enzymes produced by other organisms around them.

3. This general category also includes slime molds which are often brightly colored creatures that creep over wood and other decaying vegetation.

1. Many common algae are grass-green organisms related to land plants and are placed in the plant kingdom for that reason.

2. Other algae are red, golden-brown, yellow-green, brown, and even colorless.

1. The green-clade algae have chloroplasts with single thylakoids (Figure 30.4).

2. In the chloroplasts of these organisms, the thylakoids then occur in bundles of three (Figure 30.4).

3. The phototrophs are also remarkable in having their chloroplasts in the lumen of the rough endoplasmic reticulum, instead of the cytosol.

4. Algal chloroplasts produce food reserves that are often stored in the pyrenoids which are visible in Figure 30.4).

1. The two main types of flagella–whiplash and tinsel–are shown in Figure 30.5.

2. The green-clade algae generally have a pair of whiplash flagella, and some have more than one pair.

3. The organisms typically have one whiplash flagellum (often pointed backward) and one tinsel flagellum (often pointed forward).

4. In some groups, only the distinctive tinsel flagellum remains.

1. Lysine is an exception to this "rule."

2. Bacteria synthesize lysine through a metabolic pathway that includes diaminopimelic acid (DAP), which is a common component of their cell walls (Figure 30.6).

3. Most eucaryotes that can make their own lysine also use the DAP pathway, but a few groups use a different pathway that includes a-aminoadipic acid (AAA) (Figure 30.6).

1. Single cells with no flagella are coccoid, and similar cells that stay cemented together in packets embedded in mucilage are called tetrasporine, even though the cells are rarely in groups of four and are not spores of any kind.

2. Many algae are filaments, often highly branched filaments, although this form is not common among chromists (Figure 30.8).

3. Filamentous algae may also have a siphonaceous form, which are long tubes not divided into cellular segments, so several nuclei reside in a single cytoplasm (a coenocytic condition).

4. Chromists also include rhizopodial algae or amoebas, so called because of their branching pseudopods (Figure 30.9).

5. Chrysophytes and xanthophytes are common members of both freshwater and marine plankton.

1. Figure 30.11 outlines the cell division cycle of a diatom.

2. Diatoms lack flagella or cilia, but remain motile because of slits (called raphes) in each half-shell which are associated with nearby bundles of contractile fibrils.

3. The fibrils move along the raphe until they adhere to some object, then they contract and if the object is large enough the diatom can move along it by means of these fibrils.

1. Most dinoflagellates are unicellular and distinctively shaped, covered with a cellulose armor divided into plates, and split by two grooves that contain flagella.

2. Some dinoflagellates use the energy of ATP to "light up" by phosphorescence in the ocean at night.

3. Other dinoflagellates are the cause of "red tide" which ultimately poisons fish and other vertebrates who feed on molluscs that have fed on the dinoflagellates.

1. Oomycetes have flagellated reproductive cells, cellulose cell walls, and some other features showing their relationship to the algae.

2. Oomycetes probably evolved from some very similar siphonaceous yellow-green algae.

3. Most oomycetes are obscure saprobes that grow in water or in moist soil, but downy mildews are plant pathogens on important crops.

1. Brown algae show little or no differentiation of their tissues other than reproductive cells. The general term for such undifferentiated multicellular organisms is thallus (plural, thalli).

2. Their tissues are made of thin-walled, box-like cells called parenchyma.

3. Brown algae may be long and filamentous, finely branched, or flat and leaflike. Some kelps form large sheets and cylinders of parenchymal cells.

4. Brown algae and other seaweeds are important in the diets of some people who live near seashores.

1. They are mostly marine and are abundant in warm tropical coastal waters, although some species live in fresh water and soil.

2. The red algae range from single cells to lacy, interwoven filaments and broad sheets, marked by distinctive red-purple colors from their phycobilin pigments (Figure 30.15).

3. The phycobilin pigments are built into distinctive particles (phycobilisomes) covering their photosynthetic membranes (Figure 30.16).

1. Coralline red algae, whose walls contain calcium deposits, are important components of coral reefs.

2. After cell division in red algae, the new wall does not close off completely but leaves a connection, like a plasmodesma in plant cells (Figure 30.17).

3. There are many similarities between the complex life cycles of many red algae and those of rust fungi (Figure 30.18).

1. These heterogeneous organisms, though united by their pseudopods, are probably not all closely related.

2. Amoeba proteus is a common freshwater example of a protozoan with probable algal roots (Figure 30.19).

3. Figure 30.19 shows an amoeba with formidable-looking pseudopods that resemble flagella.

4. Foraminiferans secrete calcium carbonate shells that eventually turn into limestone and chalk on the ocean floor.

5. Because the discarded shells of foraminiferans are so distinctive and well-preserved, geologists use them extensively to determine the ages of sediments.

1. The Apicomplexa include Plasmodium species, the agents of malaria in humans.

2. Plasmodium goes through several stages as it cycles from person to person through Anopheles mosquitoes (Figure 30.20).

1. Connecting fibrils coordinate the whole ciliary field, so the cilia beat together and the direction of movement can be changed quickly.

2. Scattered among the cilia on the surface of a cell are trichocysts that shoot out of their retracted positions when stimulated, and they can be used for defense, procuring food, or for anchoring the cell (Figure 30.22).

1. Paramecium has two kinds of nuclei: one or more small micronuclei provide genetic continuity from generation to generation and a large macronucleus, which provides the templates for protein synthesis and cellular regulation between divisions.

2. While Paramecium and other ciliates generally reproduce by asexual cell division, they occasionally engage in conjugation, or sexual mating (Figure 30.23).

1. Some species of slime molds are white, but most are red, orange, or yellow.

2. All slime molds feed and grow as amoeboid cells and then develop fruiting bodies that produce spores.

1. The diploid plasmodium stops moving and sends up fruiting bodies in which masses of haploid spores form by meiosis (Figure 30.24).

2. After falling to the ground, these spores germinate into flagellated gametes, which fuse in pairs to make new diploid vegetative cells.

3. Each cell then begins to move about as an amoeba again.

1. The well-studied Dictyostelium consists of independent, uninucleate amoeboid cells that feed phagocytically as they move over the soil and divide repeatedly into more uninucleate cells (Figure 30.25).

2. The cells recruit one another and stream into a central point where they form a pseudoplasmodium, so called because the cells retain their cellular identities and do not form a coenocyte.

3. There are no sexual events in this cycle, and all stages are apparently haploid.

1. John Dodge showed that the chromosomes of dinoflagellates look more like the nuclear bodies of bacteria than the chromosomes of other eucaryotes (Figure 30.27).

2. Donna Kubai and Hans Ris showed that some dinoflagellates undergo mitosis as shown in Figure 30.28, where the nuclear envelope does not break down.

3. The several chromosomes divide rather like those of bacteria, but with the aid of a new eucaryotic feature, microtubules.

1. Kinetochores were initially plaques in the nuclear envelope to which the chromosomes were bound. Later the kinetochores became permanently attached to the chromosomes, and the nuclear envelope no longer had any role in mitosis.

2. The spindle was initially extranuclear, then some spindle elements began to separate the chromosomes by attaching directly to the kinetochores.

1. Although their chromosomes are like those of other eucaryotes, their nuclei still divide by elongating and pinching in two, as the nuclei of dinoflagellates do.

2. They use the AAA pathway of lysine synthesis.

3. They have flagella with only a single row of filaments.

4. They have a gullet into which they take small bits of food.

5. They have a brightly colored eyespot near the gullet that is apparently a light receptor.

6. They have a peculiar squirming motion in which the cell alternately bulges and narrows.

1. The euglenoids are thought to be close relatives of the trypanosomes, a group that includes such parasites as the causative agent of African sleeping sickness (Figure 30.31).

2. The tsetse fly is a vector that carries these trypanosomes between humans and various animals.

1. This theory is mainly championed by Lynn Margulis.

2. According to this model, the primitive eucaryotic cell was fundamentally anaerobic and lived by fermentation.

3. Then some cells acquired endosymbionts that transformed their metabolism.

1. This model supports the idea that mitochondria could be derived from internal changes in a cell.

1. Figure 30.35 shows the life cycle of the chytrid Allomyces.

2. Chytrids are not true fungi because they have flagella and they reproduce with motile spores powered by a single posterior flagellum.