Cell nucleus
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The eukaryotic cell nucleus. Visible in this diagram are the ribosome-studded double membranes of the nuclear envelope, the DNA (complexed as chromatin), and the nucleolus. Within the cell nucleus is a viscous liquid called nucleoplasm, similar to the cytoplasm found outside the nucleus.
A cell nucleus is a small round object found inside a cell. It contains genes that have DNA inside it, which are the building blocks of life. The human body contains billions of cells and that means billions of nuclei (nuclei is the plural of Nucleus).
Egg yolks are nuclei. Ostrich eggs have the largest yolks and that means they have the largest nuclei. Some viruses attack the nucleus of a cell to use it to make more viruses.
Some animals (like amoebas) are animals made up of one cell and they reproduce by splitting in half. This means that an amoeba is a single-celled organism (living thing). Many bacteria are single-celled organisms.
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