Bio-Ch 29 Protists

Filopodia

Pseudopods. Thin extended and branching protrusions

Axopodia

Pseudopods. extend long, thin pseudopods called axopodia supported by axial rods of microtubules. Axopodia can be extended or retracted.

Meiosis

major evolutionary innovation that arose in ancestral protists and allows for the production of haploid cells from diploid cells. Fertilization is union of 2 haploid cells.

Pseudopods

means of locomotion

Endosymbiont theory

mitochondria and chloroplasts evolved from engulfed bacteria that remained intact.

Diatoms (Cromalveolata->stramenopiles)

photosynthetic, unicellular organisms with unique double shells made of opaline silica, which are often strikingly marked.

Mixotrophs

protists that are both phototrophic and heterotrophic. Tremendous nutritional flexibility.

phylogenetic

relating to the evolutionary development of organisms.

Obligate

restricted to a particular function or mode of life.

Budding

when daughter cell after mitosis is smaller than parent and then grows to adult size

monophyletic

(of a group of organisms) descended from a common evolutionary ancestor or ancestral group, esp. one not shared with any other group.

Cromalveolata

A supergroup that may have arisen by one or more secondary endosymbiosis events. Includes Alveolata and Stramenopila.

Phagotrophs

Among heterotrophic protists, phagotrophs, which ingest visible particles of food by pulling them into intracellular vesicles called food vacuoles or phagosomes.

Apicomplexans (Cromalveolata->Alveolata)

Apicomplexans are spore-forming parasites of animals. They are called Apicomplexans because of a unique arrangement of fibrils, microtubules, vacuoles, and other cell organelles at one end of the cell, termed an apical complex. The apical complex is a cytoskeletal and secretory complex that enables the apicomplexan to invade its host cell. The best known apicomplexan is the malarial parasite Plasmodium.

Endosymbiotic Bacteria

Bacteria that live within other cells and perform specific functions for their host cells

Stramenopiles (Cromalveolata)

Brown algae, diatoms and oomycetes (water molds) make up stramenopiles within the cromalveolates.

Excavata

Diplomonads, parabasilids, euglenozoans are grouped as Excavata (the excavates) based on cytoskeletal and DNA sequence similarities showing evolutionary relatedness

Secondary Endosymbiosis

Eukaryotic cell with chloroplast for example swallowed by another eukaryotic incorporating chloroplasts into its cell.

Kinetoplastids (Excavata->Euglenozoa)

Has a unique single mitochondrion within the cell. The mitochondria have two types of DNA: minicircles and maxi circles. This mitochondrial DNA is responsible for very rapid glycolysis and also for an unusual kind of editing of the RNA by guide RNAs encoded in the mini circles.

Euglenozoa (Excavata)

One of the earliest free-living eukaryotes to possess mitochondria. Both free-living euglenids and parasitic kinetoplastids are considered euglenozoans. Some euglenids have chloroplasts and are fully autotrophic; others lack chloroplasts, and ingest their food, and are heterotrophic. Reproduction occurs through mitotic cell division. No sexual reproduction is known to occur in this group.

Parabasilids (Excavata)

Parabasilids have undulating membranes (move with a smooth wavelike motion). Some live in gut of termites and digest cellulose, the main component of the termite's wood-based diet. Some parabasilids have a symbiotic relationship with bacteria which aids in the digestion of cellulose. Parabasilids also lack mitochondria and use flagella to move.

Lobopodia

Pseudopods with large, blunt extensions of the cell body

Osmotrophs

Protists that ingest food in soluble form are called osmotrophs.

Trypanosomes (Excavata->Euglenozoa->Kinetoplastids)

Trypanosomes are a group of kinetoplastids that cause many serious human diseases, the most familiar being trypanosomiasis, also known as being African sleeping sickness, which causes extreme lethargy and fatigue. Leishmaniasis, which transmitted by sand flies infected with the protists parasite Leishmania, is a trypanosomic disease that causes skin sores and in some cases can affect internal organs leading to death. Chagas disease is caused by Trypanosoma cruzi. Can lead to severe cardiac and digestive problems in humans and animals, but appears to be tolerated in the wild mammals.

Diplomonads (Excavata)

Unicellular and move with multiple flagella. This group lacks Mitochondria but may contain mitochondrial genes and has two nuclei. The parasite, Giardia intestinal, is an example of a diplomonad.

Gregarines (Cromalveolata->Alveolata->Apicomplexan)

another type of Apicomplexans that use their distinctive apical complex to attach themselves in the intestinal epithelium of arthropods, annelids, and mollusks. Most of the gregarine body, aside from the apical complex, is in the intestinal cavity, and nutrients appear to be obtained through the apicomplexan attachment to the cell.

Carotenoid

any of a class of mainly yellow, orange, or red fat-soluble pigments, including carotene, which give color to plant parts such as ripe tomatoes and autumn leaves.

Dinoflagellates (Cromalveolata->Alveolata)

are photosynthetic unicells with two flagella. Plates made of a cellulose like material, often encrusted with silica, encase the Dinoflagellate cells. Grooves at the junctures of these plates usually house the flagella, one encircling the cell like a belt, and the other perpendicular to it. Most Dinoflagellates have chlorophylls a and c, in addition to carotenoids. When toxic Dinoflagellates are abundant, many fishes, birds, and marine mammals may die. Although sexual reproduction does occur under starvation conditions, Dinoflagellates reproduce primarily by asexual cell division.

Binary Fission

asexual reproduction like cell division of prokaryotes/bacteria.

Phototrophs

autotrophic protists that are photosynthetic

Oxidative Metabolism

breaking down of molecules into energy/atp

Endosymbiosis

energy producing bacteria may have come to reside within larger bacteria, eventually evolving into what we now know as mitochondrion.

Cysts

dormant forms with resistant outer coverings in which cell metabolism is more or less completely shut down.

Ciliates (Cromalveolata->Alveolata)

have two different types of nuclei within their cells: a small micronucleus and a larger macronucleus. Macronuclei divide by mitosis. Micronucleus needed for sexual reproduction. -Ciliates form vacuoles for ingesting food and regulating water balance.

stigma (chlorophyta)

helps photosynthetic organisms move toward light.

Alveolata (Cromalveolata)

including the dinoflagellates, apicomplexans, and ciliates, all of which have a common lineage but diverse modes of locomotion. A common trait is the presence of flattened vesicles called alveoli stacked in a continuous layer below their plasma membranes.

Pellicle

interlock proteinaceous strips arranged in a helical pattern form a flexible structure called the pellicle, which lies within the plasma membrane of the euglenids. Because its pellicle is flexible, a euglenid is able to change its shape.

Asexual Reproduction

involves mitosis

Heterotrophs

obtain energy from organic molecules synthesized by other organisms.

Conjugation

sexual process in which two individual cells remain attached to each other for up to several hours.

Cytoproct

special pore in paramecium that is an exocytotic vesicle that appears periodically when solid particles are ready to be expelled. -Contractile vacuole regulate water balance, periodically expand and contract as they empty their contents to the outside of the organism.

Cytokinesis

the physical process of cell division that divides the cytoplasm of a parent cell into two daughter cells.

Toxoplasma (Cromalveolata->Alveolata->Apicomplexan)

using its apical complex, toxoplasma gondii invades the epithelial cells of the human gut. Most individuals infected with the parasite mount an immune response, preventing any permanent damage. Individuals with AIDS are particularly susceptible to Toxoplasma infection. If a pregnant women touches a litter box of an infected cat, toxoplasma parasites from the cat can, if ingested, cross the placental barrier and harm the developing fetus with an immature immune system. The ciliates have a pellicle, a tough but flexible outer covering, that enables them to squeeze through or move around obstacles.