Eukaryota

Eukaryotes may consist of a single cell or they may be multicellular organisms - termed Metazoa - made up of differentiated (specialized) cells. They may be unicellular in all their developmental stages (protists), or unicellularity may be limited to certain developmental stages, such as the sexual stages (gametes) of plants and animals. Even highly differentiated Metazoa retain vestiges of their unicellular origin, as shown by their development from unicellular “eggs”, some of which may develop even if they are not fertilized. They also have the ability to reconstruct their whole bodies from a single cell, as do easily the sponges, but also the fertilized oocytes of vertebrates. Eukaryotic cells consist of a membrane-bound cytoplasm(containing one or more nuclei and various organelles that are also often membrane-bound, their compartments and membranes acting as sites) where reaction processes can occur. The most significant differences between the components of eukaryotic...