Protist1 - morphology. At some stages in their life cycle,...

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Protista Sarcodina Sarcodina have no flagella or cilia. They move by means of ameboid motion. Helped by filaments of a structural protein called actin, the cytoplasm of these protozoa can flow beneath the cell membrane into new branches called pseudopods, causing the cell to move in a given direction. Many sarcodina are parasites of the intestinal track and oral cavity of humans and other vertebrates. We are most familiar with the formless genus Ameba seen in , but many sarcodina secrete hard silica- or calcium carbonate-based shells, sometimes in elaborate, species- specific shapes. Shells made of calcium carbonate have been significant in forming many of the world's limestone deposits. Slime Molds The slime molds warrant their own classification within Protista because of their unusual
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Unformatted text preview: morphology. At some stages in their life cycle, they show clearly protozoan characteristics, but at other stages they become almost fungus-like. Slime molds fall into two distinct groups that are not closely related: the cellular slime molds and the true, or acellular, slime molds. A distinguishing morphological difference between the two groups is the vegetative state of cellular slime molds in a haploid amebiod cell, whereas the vegetative state of acellular slime molds is a multinucleate diploid ameboid mass called a plasmodium. Both groups grow in moist soil or decaying plant matter and are white, yellow, or red in color....
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