Protists

=Protists!=

__The Kingdom Protista__

The definition of a protist is a rather foggy one, as they are definined as any eukaryotic organismd that aren't a plant, animal, fungus, or prokaryote. The word **//Protista//** comes from a Greek word meaning "the very first", as protists were the first eukaryotic organisms. They are believed to have come about from the symbiosis of several cells, and some of there organelles may have come from photosynthetic prokaryotes. Most biologists categorize protists into smaller groups based on how they obtain nutrition; the three main protist groups are animal like protists, plant-like protists, and fungus-like protists. These classifications, however, are not very scientifically accurate as they do not represent the evolutionary history of these organisms.

__Animal-like Protists__



They were once called protozoa, meaning "first animals" and and be classified into four phyla: zooflagellates, sarcodines, ciliates, and sporozoans. They are thus split into these categories by means of movement, each moving in a way far different than the next.

//Zooflagellates//-They are of the phylum Zoomastigina, because they use long, whilplike flagella to move. They tend to usually have one to two flagella, absorb food through their cell membrane, and reproduce asexually(most often). //Sarcodines//-They belong to the phylum Sarcodina; they move using pseudopods(cytoplasmic projections). They thrust these forward, following with the rest of the cell body. To obtain food, they surround and absorb it via food vacuoles; they reproduce by mitosis and cytokinisis. //Ciliates//-The phylum ciliophora is where they reside, using short cilia projections(similar to flagella, only smaller) to feed and mobilize. The genus Paramecium, one of their subgroups, is a good representative of the internal anatomy of the phylum. They contain trichocysts, a structure used for defense; a mocronucleus, where genetic information is stored; a micronucleus, where a reversed copy of the genes are stored; gullet, to trap food; anal pore, to release wastes; and contractile vacuoles, storing excess water. They can reproduce via conjugation, the exchange of genetic material. //Sporozoans//-They are members of the phylum Sporozoa; they reproduce by sporozoites which attach to host cells and live within it. They are parasites that are unable to move of their own will.

They can cause some horrible diseases:
 * Malaria by sporozoan Plasmodium
 * African Sleeping Sickness by zooflagellates Trypanosoma
 * Amebic Dysentary by Entamoeba

They are important to the world as some live symbiotically, breaking down organic matter or serving as food to small animals in lakes.

__Plantlike Protists__



Algae can be defined as plant-like protist; they are of two groupings: unicellular and multicellur.

Unicellular algae are divided into four phyla: euglenophytes, chrysophytes, diatoms, and dinoflagellates. They are often classified by the type of photosynthetic pigments they contain; they have adapted accessory pigments and chlorophyll to allow themselves to capture more energy, that hasn't been absorbed by the water.

//Euglenophytes//-They have two flagella, but lack a cell wall, making them relatives to zooflagellates. They reproduce by binary fission, have a cell membrane called a pellicle, and have an eyeyspot to help them find sunlight. //Chrysophytes//-They have gold colored chloroplasts, ergo their name; they are yellow-green and golden-brown algae. They reproduce both asexually and sexually, have cell walls of pectin and cellulose, and store food as oil instead of as starches. //Diatoms//-They are of the phylum Bacillariophyta, and form thin cell walls full of silicon. They are shaped like a petri dish, containing two sides fitted together with lines and patterns. //Dinoflagellates//-They belong to the phylum Pyrrophyta; they can be both photosynthetic and heterotrophic. They are often luminiscent, contain two flagella, and reproduce through binary fission.

They, as phytoplankton, carry out half of the photosynthesis occuring on Earth, providing sustenance to underwater organism. They also sometimes bloom and form colonies to recycle sewage waste in the sea; however, when to many come together, they rid the water of nutrients and die leaving befind a poisonous residue.

//Red Algae//-They are of the phylum Rhodophyta; they have chlorophyll a and phycobilins(accessory pigments). They play a part in the formation of coral reefs, and can absorb blue light and therefore live deep in the ocean. //Brown Algae//-The phylum Phaeophyta is where they are placed; they consist of chlorophyll a and c, and fucoxanthin. They consist of blades, a bladder, a stipe, and a holdfast; they are the most complex and biggest of all algae. //Green Algae//-They belong to the phylum Chlorophyta; they are photosynthetic and have cell walls. They have chloropyll a and b, and cellulose in their cell walls. There is unicellular, colonial, and multicellular green algae in existence. They reproduce both asexually and sexually, partaking in the alternation of generation(living sometimes as haploids and sometimes as diploids).

Algae are not only food for ocean dwellers and sorce of oxygen, but are used in human foods and chemical. They can be found in plastics, transistors, deodorant, artificial wood, nori(sushi seaweed), ice cream, and much more.

__Funguslike Protists__



They live in damp environments, absorb food through cell membranes, have centrioles, and lack chitin cell walls. They are divided into three groups: Cellular Slime Molds, Acellular Slime Molds, and Water Molds.

Slime Molds recycle organic matter. Cellular Slime Molds(phylum Acrasiomycota)throughout their lifetimes, are separated from one another by cell membranes, where as Acellular(phylum Myxomycota) ones fuse to form large cells for a time.

Water molds are of the phylum Oomycota; they are either plant parasites or reside on dead and decaying organic matter.

They are important as they recycle organic material, making things rot. But, they also are a cause of disease. They, the Phytophthora infestans protist, caused the potato famine in Ireland.