Protists

Protists is a group of eukaryotic microorganisms and don't have a lot in common except for their simple organization. They are not classified as members of kingdoms Plantae, Animalia, or Fungi. They are not a plant, animal, prokaryote, or fungus. They are either unicellular or multicellular. They are without specialized tissues and apart from other eukaryotes, protists cellular organization distinguishes with organisms like fungi, plants, and animals. They evolved independently from archaebacteria proven by recent studies of their DNA. Protist live in environments that contain water and many are algae that are vital primary producers in ecosystems, especially in the ocean as plankton. Some protist are responsible for severe human dieases such as Kinetoplastids and Apicomplexa which cause malaria and some sleeping sicknesses. Taxonomy of protists is alway changing and newer classifications become present constantly.

A way to classify protist is the way they obtain nutrition.

Animal like protist that use flagella to swim are classified as Zooflagellates. They absorb food through their cell membrane and live in water where they are able to absorb their necessary nutrients from organic decaying material. Others live inside another organism. They reproduce both asexually and sexually. Sexual reproduction is by binary fission.

Sarcodines are another animal like protist. They use for feeding and movement pseudopods. They known are amoebas. They are flexible active cells with pseudopods extending out central mass of the cell. They capture and digest food particles and other cells. Foraminiferans are another sarcodina that are abundant in water regions of the ocean. They secrete shells of calcium carbonate and when they die the calcium carbonate collects at the bottom of the ocean. Ciliates use cilia for feeding and movement. Sporozoans are parasitic and do not move on their own. Most sporozoans have complex life cycles and require more than one host.

Plantlike protist are known as algae. In algae, accessory pigments and chlorophyll are what allow for the protist to harvest and then use the energy they get from the sunlight.

Euglenophytes have two flagella but they do not have any cell walls. They do have a pellicle which is their cell membrane. It is folded in a ribonlike ridges and each supported by microtubules. It is tough and flexible which allows for the euglenas to crawl through the mud. Euglenophytes reproduce asexually binary fission. Another plantlike protist is the Chrysophyte. They have very golden colored chloroplasts. Their cell walls have carbonhydrate pectin instead of cellulose, but their are some that have both pectin and cellulose. They store food in oil form. They reproduce asexually and sexually.

Diatoms, tiny and jewellike, produce a thin delicate cell wall that is rich with silicon. Their cell walls are shaped similar to a petri dish. Their cell wall has fine lines.

Dinoflagellates have two flagella and wrap around organisms. They are mostly photosynthetic or they can be heterotrophs. When they are irritated they give off light. In some areas of the ocean have many these protist and when a boat moves it causes the water to shimmer. They are often called the fire plants.

There is another type of plantlike protist that are known as red, brown, and green algae. The red algae can live in great depths due because of their efficeiency to havest light energy. They contain phycobilins that are red accessory pigments and also chlorophyll //a//. Brown algae also have chlorophyll //a,// but they also have chlorophyll //c//. Their accessory pigment is called fucoxanthin which is a brown accessory pigment. The green algae have many of the same characteristics as other plants. They have photosynthetic pigments and their cell wall composition is very similar to other plants.

The last type of protist is the funguslike protist. They are heterotrophs and absorb nutrients from decaying or dead organic material. But they are different than the true fungi because they have centrioles and they lack a chitin cell wall.

Slime molds can be found in soil mostly. They live on decaying material and play a key role in recycling organic material. Their are two different types of slime molds; cellular and acellular.

The other type of funguslike protist is the water mold. They thrive off of dead organic matter that is decaying in water, but there are other water molds that are parasites on plants on land. They produce hyphae, a thin filament. The hyphae do not have walls inbeween their cells and are multinucleate. Their cell walls are made of cellulose and produce motile spores. They reproduce asexually and sexually.