organisms may be unicellular or multicellular
organisms may or may not have cell walls
organisms have extensive internal membranous organelles
organisms have a nucleus to organize DNA
cells are larger (10-100 uM on average)
Eukaryote, organism whose cells contain a nucleus, a saclike structure that encloses the cell’s hereditary materials. The presence of a nucleus distinguishes eukaryotes from prokaryotes, those simple, one-celled organisms in which the hereditary material floats free within the cell. Unlike prokaryotes, eukaryotes display a tremendous diversity of form, from complex, single-celled amoebas, diatoms, and dinoflagellates to multicellular plants, animals, and fungi.
Only the eukaryotic cell is capable of a high degree of specialization, and specialization is what makes multicellular organisms possible. Just as banks, post offices, and other specialized workplaces are intrinsic to a city, cells tailored for certain jobs are intrinsic to more-complex organisms. Working in concert, specialized cells can create a higher level of organization known as tissues, such as the growing shoot of a plant or the spiny skin of a sea star. Coordinated tissues form organs and, in animals, these organs combine to form complex organ systems, such as the circulatory, digestive, and respiratory systems. The orchestration of these organ systems makes up the organism.
Article key phrases:
dinoflagellates, eukaryotic cell, diatoms, specialized cells, sea star, eukaryotes, cell walls, respiratory systems, certain jobs, post offices, orchestration, nucleus, DNA, organisms, animals, uM, banks, cells, complex, plant, simple, city, concert, Working