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A drawing of a prokaryotic cell. There are two fundamental classifications of cells: prokaryotic and eukaryotic. Prokaryotic cells are distinguished from eukaryotic cells by the absence of a cell nucleus or other membrane-bound organelle. [10] Prokaryotic cells are much smaller than eukaryotic cells, making them the smallest form of life. [11]
The division between prokaryotes and eukaryotes has been considered the most important distinction or difference among organisms. The distinction is that eukaryotic cells have a "true" nucleus containing their DNA , whereas prokaryotic cells do not have a nucleus.
The DNA of a prokaryotic cell consists of a single circular chromosome that is in direct contact with the cytoplasm. The nuclear region in the cytoplasm is called the nucleoid. Most prokaryotes are the smallest of all organisms, ranging from 0.5 to 2.0 μm in diameter. [1] [page needed] A prokaryotic cell has three regions:
Eukaryotic cells contain membrane bound organelles. Some examples include mitochondria, a nucleus, or the Golgi apparatus. Prokaryotic cells probably transitioned into eukaryotic cells between 2.0 and 1.4 billion years ago. [31] This was an important step in evolution. In contrast to prokaryotes, eukaryotes reproduce by using mitosis and meiosis.
English: A diagram of a typical prokaryotic cell. This diagram, made in Adobe Illustrator, is an improved version of a similar diagram, Prokaryote cell diagram.svg, which was also made by LadyofHats. Besides general appearance changes, this version adds plasmids and pili, and notes that DNA is circular.
There is an important difference between a mistake and a correction. Perhaps you will understand the third time I say it: In this diagram, the yellow is the cell wall and the label "capsule" should be removed. I don't know how I can make that correction any clearer. --EncycloPetey 12:46, 24 October 2007 (UTC)
Due to their structural differences, eukaryotic and prokaryotic cells do not divide in the same way. Also, the pattern of cell division that transforms eukaryotic stem cells into gametes ( sperm cells in males or egg cells in females), termed meiosis, is different from that of the division of somatic cells in the body.