Kingdom Protista Chapter Amoeba
The amoeba is a protozoan that belongs to the Kingdom Protista, phylum sarcodina. The name amoeba comes from the Greek word amoibe, which means change. Protists are microscopic unicellular organisms that don't fit into the other kingdoms. Some protozoans are considered plant-like while others are considered animal-like. The ameba is considered an animal-like protist because it moves and consumes its food. Protists are classified by how they move, some have cilia or flagella, but the amoeba has an unusual way of creeping along by stretching its cytoplasm into fingerlike extensions called pseudopodia. (The word "pseudopodia" means "false foot".) When looking at amoeba under a microscope, an observer will note that no amoeba looks the same as any other, the cell membrane is very flexible and allows for the amoeba to change shape. Amoebas live in ponds or puddles, and can even live inside people.
There are two types of cytoplasm in the amoeba, the darker cytoplasm toward the interior of the protozoan is called endoplasm, and the clearer cytoplasm that is found near the cell membrane is called ectoplasm. By pushing the endoplasm toward the cell membrane, the amoeba causes its body to extend and creep along. It is also by this method that the amoeba consumes its food. The pseudopodia extend out and wrap around a food particle in a process call phagocytosis. The food is then engulfed into the amoeba and digested by the enzymes contained in the amoeba's lysosomes. As the food is digested it exists in a structure called a food vacuole.
Also visible in the ameba is the nucleus, which contains the amoeba's DNA.The method of reproduction is called binary fission. Another structure easily seen in the amoeba is the contractile vacuole, whose job is to pump out excess water so that the amoeba does not burst.
During unfavorable conditions, the amoeba can create a cyst, this hard-walled body can exist for a long period of time until conditions become favorable again. At this point it opens up and the amoeba emerges. Often cysts are created during cold or dry periods where the amoeba could not survive in its normal condition.
Amoeba Questions:
1. How does an amoeba move?
2. What structure contains the amoeba's DNA?
3. How does an amoeba reproduce?
4. During unfavorable conditions, an amoeba forms a ... ?
5. Fingerlike extensions of the amoeba's cytoplasm are called ...?
6. What disease is caused by the amoeba?
7. To what Kingdom does the amoeba belong?
8. How are protozoans classified?
Paramecium
Paramecium are unicellular protozoans classified in the phylum Ciliophora (pronounced sill-ee-uh-FORE-uh), and the Kingdom Protista. They live in quiet or
stagnant ponds and are an essential part of the food chain. They feed on algal scum and other microorganisms, and other small organisms eat them. All members of the Phylum Ciliophora move by tiny hair-like projections called cilia.
The paramecium cannot change its shape like the ameba because it has a thick outer membrane called the pellicle. The pellicle surrounds the cell membrane.
There are two types of nuclei (plural of nucleus). The large nucleus is called the macronucleus which controls respiration, protein synthesis and digestion. The much smaller micronucleus is used only during reproduction,. Reproduction in paramecium involves the exchanging of DNA within the micronucleus. In order to do this, two paramecium lie side by side and join at the mouth pore. This process is called conjugation and is a method of sexual reproduction in other microorganisms.
Contractile vacuoles are used in animal cells to remove the excess water. The contractile vacuole is shaped like a star.
Paramecium are heterotrophs, meaning they must consume food for their energy. Food enters the paramecium through the mouth pore and goes to the gullet. At the end of the gullet, food vacuoles are formed. Food vacuoles then remain in the cytoplasm until the food is digested. Undigested food particles are eliminated through the anal pore.The indented area where food enters the paramecium is referred to as the oral groove.
behavior. This is where the paramecium will move away from a negative or unpleasant stimulus.
There are 2 kinds of cytoplasm in the paramecium. The cytoplasm around the edges is clear and is called ectoplasm. The rest of the cytoplasm is more dense is called
endoplasm.
1. Cilia
2. Pellicle
3. Macronucleus
4. Micronucleus
5. Contractile Vacuole
6. Mouth Pore
7. Gullet
Paramecium Questions:
1. Is the paramecium a unicellular or multicellular organism?
2. To what Phylum and Kingdom do paramecium belong?
3. Define heterotroph.
4. What do paramecium eat?
5. How do all members of the Phylum Ciliophora move?
6. Why can't the paramecium change shape like the amoeba?
7. What is the function of the contractile vacuole?
8. What is the function of the trichocysts?
Euglena
Euglena are unicellular organisms classified into the Kingdom Protista, and the Phylum Euglenophyta. All euglena have chloroplasts and can make their own food by
photosynthesis. They are not completely autotrophic though, euglena can also absorb food from their environment; euglena usually live in quiet ponds or puddles.
Euglena move by a flagellum (plural-flagella) which is a long whip-like structure that acts like a little motor. The flagellum is located on the anterior (front) end, and twirls in such a way as to pull the cell through the water. It is attached at an inward pocket called the reservoir.
The Euglena is unique in that it is both heterotrophic (must consume food) and
autotrophic (can make its own food). Chloroplasts within the euglena trap sunlight that is used for photosynthesis, and can be seen as several rod like structures throughout the cell. Euglena also has an eyespot at the anterior end that detects light; it can be seen near the reservoir. This helps the euglena find bright areas to gather sunlight to make their food. Euglena can also gain nutrients by absorbing them across their cell
membrane, hence they become heterotrophic when light is not available, and they cannot photosynthesize.
The euglena has a stiff pellicle outside the cell membrane that helps it keep its shape, though the pellicle is somewhat flexible and some euglena can be observed scrunching up and moving in an inchworm type fashion (Euglenoid movement).
In the center of the cell is the nucleus, which contains the cell's DNA and controls the cell's activities. The nucleolus can be seen within the nucleus.
Euglena Questions:
1. Are euglena unicellular or multicellular?
2. What Kingdom do euglena belong to? What Phylum?
3. What organelle carries out photosynthesis?
4. On which end is the flagellum located?
5. Define autotrophic.
6. Define heterotrophic.
7. Describe the two ways in which the euglenas get their nutrients.
8. What is the eyespot used for?
9. What is the function of the nucleus?
Diatoms
(Greek: (dia) = "through" + (temnein) = "to cut", i.e., "cut in half") are a major group of eukaryotic algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons. Diatoms are producers within the food chain. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon
dioxide) called frustule. These frustules show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides, like the two halves of a petri dish, with a split between them, hence the group name.
Fossil evidence suggests that they originated during, or before, the early Jurassic Period. Diatom communities are a popular tool for monitoring environmental conditions, past and present, and are commonly used in studies of water quality.
There are more than 200 genera of living diatoms. Diatoms are a widespread group and can be found in the oceans, in freshwater, in soils and on damp surfaces. They are especially important in oceans, where they are estimated to contribute up to 45% of the total oceanic primary production (making carbon compounds from carbon dioxide). Although usually microscopic, some species of diatoms can reach up to 2 millimetres in length.
Diatomaceous earth is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder, with a particle size extending from less than 1 to over 100 microns, but typically around 2 to 10 microns. This powder has an abrasive feel, similar to pumice powder, and is very light, due to its high porosity. The typical chemical composition of diatomaceous earth is 86% silica, 5% sodium, 3% magnesium and 2% iron.
Filtration
The most common use (68%) of diatomaceous earth is as a filter medium, especially for swimming pools. It has a high porosity, because it is composed of microscopically small, coffin-like, hollow particles. It is used in chemistry under the brand name Celatom or Celite as a filtration aid, to filter very fine particles that would otherwise pass through or clog filter paper. It is also used to filter water, particularly in the drinking water treatment process and in fish tanks, and other liquids, such as beer and wine. It can also filter syrups and sugar.
Abrasive
The oldest use of diatomite is as a very mild abrasive and, for this purpose; it has been used both in toothpaste and in metal polishes, as well as in some facial scrubs.
Pest control
Diatomite is also used as an insecticide, due to its absorptive properties. The fine powder absorbs lipids from the waxy outer layer of insects' exoskeletons, causing them to dehydrate. Arthropods die as a result of the water pressure deficiency. This also works against gastropods and is commonly employed in gardening to defeat slugs
Diatom Questions:
1. What is a frustule? What is the main component of this structure?
2. List some environments where you would find diatoms?
3. How is diatomaceous earth made?
4. List some uses for diatomaceous earth.
Many of the worlds white sand beaches are due to massive