Cell nucleus

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Cells in tissue culture stained for DNA with the blue Hoechst dye. The middle and right cells are in interphase, so their entire nuclei are labeled. On the left a cell is going through mitosis and its DNA has condensed, ready for division.
The eukaryotic cell nucleus. Seen here are the ribosome-dotted double membranes of the nuclear envelope, the DNA complex, and the nucleolus.

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 chromosomes which house the DNA. Chromosomes are more widely recognised by the shape they form during cell division. 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 organelles.

Some eukaryotes (like amoebas) consist of only one cell with the same basic materials as multi-cellular organisms.

Within the nucleus is a structure called a nucleolus. It contains DNA and RNA and is floating in an envelope of watery liquid called nucleoplasm.

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