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In the first the cell extends small pseudopods which then move down the sides of the cell, acting like paddles. [9] [10] [12] In the second the cell generates an internal flow cycle, with the cytoplasm flowing backward along the membrane edge and forward through the middle, generating a force on the membrane which moves the cell forward. [10] [12]
Cells which use flagella for movement are usually referred to as flagellates, cells which use cilia are usually referred to as ciliates, and cells which use pseudopods are usually referred to as amoeba or amoeboids. Other protists are not motile, and consequently have no built-in movement mechanism.
Clockwise from top right: Amoeba proteus, Actinophrys sol, Acanthamoeba sp., Nuclearia thermophila., Euglypha acanthophora, neutrophil ingesting bacteria. An amoeba (/ ə ˈ m iː b ə /; less commonly spelled ameba or amœba; pl.: amoebas (less commonly, amebas) or amoebae (amebae) / ə ˈ m iː b i /), [1] often called an amoeboid, is a type of cell or unicellular organism with the ability ...
The stage in which water flows into the CV is called diastole. The contraction of the contractile vacuole and the expulsion of water out of the cell is called systole. Water always flows first from outside the cell into the cytoplasm, and is only then moved from the cytoplasm into the contractile vacuole for expulsion. Species that possess a ...
An amoeba of the genus Mayorella (Amoebozoa, Discosea). Amoebozoa is a large and diverse group, but certain features are common to many of its members. The amoebozoan cell is typically divided into a granular central mass, called endoplasm, and a clear outer layer, called ectoplasm.
(B) An amoeboid cell with leptopodia, nucleus, and food inclusions. (C) Time series of locomoting amoeba. (D) Three amoebae showing the distribution of F-actin (phalloidin) in leptopodia (arrowheads) and adhesion zones (dashed circles). Scale bars: 5 μm. Idionectes is a unicellular protist that lives in water. [7]
In some cases the cell moves by "walking", with relatively permanent pseudopodia serving as limbs. The most important genera are Amoeba and Chaos, which are set apart from the others by longitudinal ridges. The best known of the species in this family is Amoeba proteus, commonly used in classrooms to demonstrate movement by pseudopodia.
In saline water, an Amoeba will prevent the influx of salt, resulting in a net loss of water as the cell becomes isotonic with the environment, causing the cell to shrink. Placed into fresh water, Amoeba will match the concentration of the surrounding water, causing the cell to swell. If the surrounding water is too dilute, the cell may burst. [19]