Ameba Life Cycle
An ameba or amoeba is a single cell protozoan organism. Amebas are composed entirely of cytoplasm. They have a flexible membrane of ectoplasm that surrounds an inner watery center of the endoplasm, which makes up the bulk of the cell. Within the center are organelles including the nucleus, which contains the genetic material of the cell.
Amebas have a unique form of locomotion. They are able to extrude extensions of their cell membrane called pseudopods, which allow the body of the cell to flow in any direction. Amebas feed by extending their entire bodies around their prey and consuming them whole.
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Distribution
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Amebas can be found in both fresh and saltwater, soil and in parasitic relationships within other animals.
Reproductive Process
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When they are large enough, and when environmental conditions are optimal, amebas reproduce through binary fission or mitosis. This is a form of asexual reproduction where the ameba will actually split into two unique organisms.
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DNA Replication
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The ameba will first create a replica of its genetic material within the nucleus. Once complete, the nucleus will divide into two distinct nuclei. These are the foundation of the two organisms that will result from reproduction. There are four distinct phases to mitosis.
Mitosis Phases
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In the prophase of mitosis, the body of the ameba becomes spherical. In the metaphase, the chromosomes arrange themselves within the nucleus and replicate and the nuclear membrane breaks down. During the anaphase, the chromosomes move apart. In the telophase, the chomosomes separate completely and the ameba body returns to normal, then separates into two unique cells. Both organisms are genetically identical.
Sporulation
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During unfavorable environmental conditions, amoebas will replicate multiple nuclei within the cell. The cytoplasm in the parent cell will then segregate around each nucleus, and a spore case forms around each new nucleus. This produces as many as 200 spores. The parent cell will then disintegrate, releasing the spores. These will develop into amebas in more favorable conditions.
Encystation
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Some forms of ameba are capable of producing a cyst wall as a form of protection during unfavorable conditions. Within the cyst, the ameba will replicate through mitosis, producing hundreds of daughter cells that will be released when conditions are more favorable.
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