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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 ...
Species of Amoeba move and feed by extending temporary structures called pseudopodia. These are formed by the coordinated action of microfilaments within the cellular cytoplasm pushing out the plasma membrane which surrounds the cell. [11] In Amoeba, the pseudopodia are approximately tubular, and rounded at the ends (lobose). The cell's overall ...
Eukaryotic cells have a variety of internal membrane-bound structures, called organelles, and a cytoskeleton which defines the cell's organization and shape. The nucleus stores the cell's DNA, which is divided into linear bundles called chromosomes; [19] these are separated into two matching sets by a microtubular spindle during nuclear ...
The 16-cell Gonium colony shown in the diagram on the right is organized into two concentric squares of respectively 4 and 12 cells, each biflagellated, held together by an extracellular matrix. [51] All flagella point out on the same side: It exhibits a much lower symmetry than Volvox, lacking anterior-posterior symmetry.
Shown is a micrograph of an amoeba; the darker pink nucleus is central to the eukaryotic cell, with the majority of the rest of the cell's body belonging to the endoplasm. Though not visible, the ectoplasm resides directly internal to the plasma membrane. Endoplasm generally refers to the inner (often granulated), dense part of a cell's cytoplasm.
Another hypothesis is that a primitive cell underwent nucleus division, thereby becoming a coenocyte. A membrane would then form around each nucleus (and the cellular space and organelles occupied in the space), thereby resulting in a group of connected cells in one organism (this mechanism is observable in Drosophila). A third hypothesis is ...
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.
The cell on the left is going through mitosis and its chromosomes have condensed. Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis (transcription) occur.