ABSTRACT
Eukaryotic cells have a membrane-bound nucleus and a number of other membrane-bound subcellular organelles, each of which has a specific function. A eukaryotic cell is surrounded by a plasma membrane, has a membrane-bound nucleus and contains a number of other distinct subcellular organelles. The plasma membrane envelops the cell, separating it from the external environment and maintaining the correct ionic composition and osmotic pressure of the cytosol. The cytosol is the soluble part of cytoplasm where a large number of metabolic reactions take place. Within the cytosol is the cytoskeleton, a network of fibers that maintain the shape of cell. The plasma membrane, like all membranes, is impermeable to most substances but presence of specific proteins in the membrane allows certain molecules to pass through, therefore making it selectively permeable. The nucleus is bounded by the inner and outer nuclear membranes. These two membranes fuse together at the nuclear pores through which molecules can move between the nucleus and the cytosol.
