Biology chapter 26

Amoebas

Clade member of amoebozoa. Supergroup: unikonts. They have extremely flexible outer plasma membranes and so they CHANGE SHAPE AS THEY MOVE. They push out loose loose pseudopodia from the surface of the cell. They capture and engulf food by surrounding and forming a vacuole around it. (they have digestive enzymes that then digest the food). They reproduce asexually splitting into two equal parts. Some of them are parasitic like entamoeba histolytica which causes amoebic dysentery, a serious human intestinal disease characterized by severe diarrhea, bloody stools, and ulcers in the intestinal wall.

Excavate

Flagellated with unusual mitochondria, deep oral grove. Clade (members): Diplomad (Giardia), Euglenoid, Trypanosomes. Diverse group of unicellular protists with flagella and a deep or excavated oral grooves. They have GREATLY MODIFIED MITOCHONDRIA. many are endosymbionts and live in anoxic environments.

Archaeplastid

Have chloroplasts, are autotrophs. Clade (members): Red algae, green algae

Chromalveolates

Most are autotrophic. Clade (members): Alveolates (Dinoflagellate) (apicomplexan) (Ciliates), Stramenopiles (Diatoms) (brown Algae) (golden algae) (water mold)

apicomplexan

clade member of alveolates. supergroup: Chromalveolates. A group of parasitic spore forming aveolates. They contain the un-pigmented remnant of a chloroplast derived from a red algae. They lack specific structures for locomotion and they MOVE BY FLEXING. they have an APICAL COMPLEX OF MICROTUBULES that attach the parasite to the host cell. It also has the ability to form a MOVING JUNCTION which enables them to form a vacuole that encloses and protects them as they invade the host cell. They form SPOROZOITES which are small infective agents transmitted to the next host. The apicomplexan that causes malaria is the PLASMODIUM.

dinoflagellate

clade member of alveolates. supergroup: Chromalveolates. Generally unicellular. Their alveoli contain INTERLOCKING CELLULAR PLATES impregnated with silicates. They typically have TWO FLAGELLUM one wraps around the transverse groove like a belt and the other works as a rudder perpendicular to the first flagellum. Some of these protists are endosymbionts called ZOOXANTHELLAE and photosynthesize and provide carbohydrates for their invertebrate partners. They are responsible for RED TIDES.

cilliates

clade member of alveolates. supergroup: Chromalveolates. They are the most complex as they have a DEFINITE BUT CHANGEBLE SHAPE. They have thousands of fine hairlike CILIA that facilitate them in movement with such precise motion they can back it up. They have a MACRONUCLEUS (function in reproduction) and a MICRONUCLEUS (controls cell metabolism and growth). Most of them reproduce by CONJUGATION.

plasmodial slime molds

clade member of amoebozoa. Supergroup: unikonts. They have a multinucleate mass of cytoplasm that can grow up to a foot in diameter. It mainly grows over damp, decaying logs and leaf litter. When food supply dwindles or their is insufficient moisture they crawl to a surface and start reproducing. Within these structures are SPORANGIA (meiosis produces haploid spores that are extremely resistant to adverse environmental conditions). When favorable conditions arise the spores germinate and haploid cells emerge. These haploid cells are either BIFLAGELLATE SWARM CELLS or AMOEBOID MYXAMOEBIA. One plasmodial slime mold (physarum polycephalum) is very useful for research.

giardia

clade member of diplomad. supergroup: excavate. Parasitic diplomonad that has TWO HAPLOID NUCLEI which contain a complete copy of the genome. It lACKS FUNCTIONAL MITOCHONDRIA but have reduced structures that resemble mitochondria. A strand of this is a major cause of WATER BORN DIARRHEA and is spread through cysts in animal feces and inhibits the absorbance of digested nutrients.

choanoflagellate

clade member of opisthokonts. Supergroup: unikonts. They are found globally in both freshwater and marine environments. Include free swimming and sessile species that are permanently attached by a thin stalk to bacteria-rich debris. to be continued...

golden algae

clade member of the stramenopiles. supergroup: Chromalveolate. Found in both freshwater and marine environments and most are biflagellate, unicellular organisms. They contain chloroplasts. tiny scales of either silica or calcium carbonate may cover the cell. Primarily asexual reproduction and it involves the production of zoo spores. Most are photosynthetic. They compose a significant portion of the oceans NANOPLANKTON.

brown algae

clade member of the stramenopiles. supergroup: Chromalveolate. Largest and most complex of all algae commonly called seaweed. They are multicellular and their body forms are branched filaments or thick, flattened branches. Largest ones are called KELPS. The kelps have leaflike blades (where most photosynthesis occurs) and have stemlike stiles and rootlike anchoring holdfasts. They often have gas-filled bladders that provide buoyancy. Reproduction is complex: they normally have both asexual zoospores and sexual gametes which are usually biflagellate. Most have life cycles that exhibit ALTERNATION OF GENERATIONS in which they spend part of their lives as multicellular haploid organisms and part of their lives as multicellular diploid organisms. Their cell walls contain ALGIN which is commonly harvested in many products. They form underwater forests and are essential producers for those environments.

diatoms

clade member of the stramenopiles. supergroup: Chromalveolate. These are UNICELLULAR though few exist as colonies. The cell wall consists of two shells that overlap much like a PETRI DISH. Silica is in the shell and this glass-like material forms intricate patterns. Two groups one with RADIAL SYMMETRY (wheel like) and one with BILATERAL SYMMETRY (boat or needle shaped). Some are part of the FLOATING PLANKTON others grow on rocks or sediment. Movement is facilitated by the SECRETION OF SLIME. Each generation GROWS SMALLER as the glass shell cannot expand and eventually sexual reproduction occurs which produces shell less gametes. They are significant PRODUCERS in aquatic ecosystems. Their shells collect after death and form DIATOMACEOUS EARTH which are useful for many different things.

water mold

clade member of the stramenopiles. supergroup: Chromalveolate. They resemble fungi because they both have a body called a MYCELIUM that grows over organic material digesting it and then absorbing the predigested nutrients. Their HYPHAE ARE THREADLIKE AND COENOCYTIC. Their cell walls are composed of cellulose, chitin, or both. They reproduce asexually. A hyphal tip swells and a cross wall is formed. This structure is called a ZOOSPORANGIUM and tiny zoospores form and swim about and eventually form into new mycelium. THEY DID THE IRISH POTATO FAMINE.

foriminiferans

clade. Supergroup: Rhizarians. Marine Rhizarians that produce elaborate tests. The ocean contains many forms which secretes many chambered tests with pores through which cytoplasmic projections are extended. The cytoplasmic projections form a sticky, interconnected net that entangles prey. RESPONSIBLE FOR THE WHITE CLIFFS OF DOVER. Some used as index fossils.

actinopods

clade. Supergroup: Rhizarians. Mostly marine PLANKTON rhizarians with long filamentous cytoplasmic projections called axopods that protrude through pores in their shells. A cluster of microtubules strengthen the axopod. Prey becomes entangled in the accords and then cytoplasmic streams carry the prey inside the body. Some of them called RADIOLARIANS secrete elaborate beautiful glassy shells made of silica. Important marine PLANKTON.

red algae

clade. Supergroup: archaeplastid. Most are multicellular organisms and many have complex woven filaments that are delicate and feathery. They often attach to rocks. They are remarkably complex. Don't develop flagellate in their life cycle. Primarily live in warm tropical environments. Cell walls often contain thick, sticky polysaccharides that have commercial value.

green algae

clade. Supergroup: archaeplastid. They have pigments, energy reserve products, and cell walls that are chemically identical to land plants. They are photosynthetic with chloroplasts. Cell walls with cellulose. The multicellular do not have differenciated tissue. They have both sexual and asexual reproductive methods. Many produce spores asexually by mitosis: if these spores have flagella they and are motile they are called zoospores. Sexual reproduction involves gamete formation in unicellular GAMETANGIA. Many are symbionts and a few grow together with fungi and are labeled as "dual organisms" called lichens.

opisthokonts

clade. Supergroup: unikonts

amoebozoa

clade. Supergroup: unikonts. Most of them produce temporary cytoplasmic projections called pseudopodia at some point in their life cycle. The pseudopodia are lobose that is rounded and wide (as opposed to the slender projections of rhizarians).

stramenopiles

clade. supergroup: Chromalveolate. This is a very diverse clade but most of them have motile cells with two flagella one of which has tiny hairlike projections extending from the shaft.

alveolates

clade. supergroup: Chromalveolate. Unifying features are similar ribosomal DNA sequences and ALVEOLI (flattened vesicles located just inside the plasma membrane)

diplomad

clade. supergroup: excavate. Excavates that have one or two nuclei, no functional mitochondria, no golgi complex, and up to 8 flagella.

euglenoid

clade. supergroup: excavate. characterized by unusual flagellum; they have a crystalline rod in their flagellum. Also atypical mitochondria. Most are unicellular and generally have two flagellum and 1/3 ARE PHOTOSYNTHETIC. they change shape continually while they move because their PELLICLE or outer covering is flexible. Autotrophic euglenoids have chloroplasts acquired by secondary endosymbiosis. Some engulf bacteria and protists by PHAGOCYTOSIS.

trypanosomes

clade. supergroup: excavate. characterized by unusual flagellum; they have a crystalline rod in their flagellum. Also atypical mitochondria. They have a single mitochondrion that has and organized deposit of DNA called a KINETOPLASTID. BRUCEI Causes african sleeping sickness.

Unikonts

singular posterior flagellum. Clade (members): Opisthokonts (Choanoflagellate), Amoebozoa (amoebas) (plasmodial slime molds). Have triple gene fusion.

Rhizarians

unicellular amoeboids, may have hard shell called test. Clade (members): Foraminiferans, Actinopods,