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The amoeba is a protozoan that belongs to the Kingdom Protista. 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 protists are considered plant-like while others are considered animal-like. The amoeba is considered an animal-like protist (protozoan) because it moves and consumes its food. Protozoans 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 "pseudopod" 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 amoeba is the nucleus, which contains the amoeba's DNA. In order to reproduce the amoeba goes through cell division, where the nucleus duplicates its genetic material and the cytoplasm splits into two new daughter cells, each identical to the original parent. This 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. Amoebas can cause disease. A common disease caused by the amoeba is called Amoebic Dysentery. A person becomes infected by drinking contaminated water. The amoeba then upsets the person's digestive system and causes cramps and diarrhea. A person is most likely to be infected in countries where the water is not filtered or purified

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