THE EUKARYOTIC CELL Eukaryotes come from the domain Eukarya and are represented by plants, animals, protozoa, fungi, and algae. Many of those we will study in this course are unicellular but some are multicellular. The defining feature of these cells is the presence of membrane bound organelles. These are relatively fixed in place by a cell cytoskeleton, which helps to maintain the shape of the cell. The genetic material is usually not circular but is arranged linearly in one or more chromosomes. Figure 13 describes a eukaryotic cell:
Figure 13.
Eukaryotic cells tend to be larger than prokaryotes. They divide not by binary fission but through meiosis or mitosis, which will be covered later. Some have cell walls that can be made from chitin, cellulose, or silica, which is a component of some algae cell walls. Most, however, do not have a cell wall. Motility happens with flagella or cilia that are made from microtubules. The shapes of eukaryotes can vary widely from species to species.
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