A cell nucleus is the part of the cell which contains the genetic code, the DNA, and the RNA. It also controls the activities in a cell. The nucleus is small and round, and it works as the cell's control center. It contains x-shaped "duffel bags" called chromosomes, and inside the chromosomes are DNA strands. The human body contains billions of cells, which vary from blood cells that carry oxygen from one part of the body to another, nerve cells which create reactions that stimulate feelings and data, and skin cells that protect the cells underneath.
Cell nuclei are only found in eukaryotes. They were first found by Antonie van Leeuwenhoek in the 17th century. Bacteria and Archaea are single-celled organisms of quite a different type: they are prokaryotes, and their cells do not have nuclei, or membrane bound organelle.
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