| Journey into the Cell: The Nucleus | |||||
What is the nucleus? The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is commonly the most prominent organelle in the cell. 
Nucleus, Image courtesy of The Virtual Cell. What are its distinguishing characteristics? The nucleus is bounded by a double membrane called the nuclear envelope. This membrane separates the contents of the nucleus from the cytoplasm (cyto-). The envelope helps to maintain the shape of the nucleus and assists in regulating the flow of molecules into and out of the nucleus through nuclear pores. 
Nucleus with Nuclear Pores, Copyright Dennis Kunkel. Chromosomes are also located in the nucleus. When a cell is "resting" i.e. not dividing, the chromosomes are organized into long entangled structures called chromatin and not into individual chromosomes as we typically think of them. The nucleus also contains the nucleolus which helps to synthesize ribosomes. The nucleolus contains nucleolar organizers which are parts of chromosomes with the genes for ribosome synthesis on them. Copious amounts of RNA and proteins can be found in the nucleolus as well. 
Nucleolus, Image courtesy of The Virtual Cell. 
Liver Cell Nucleus with Dark Nucleolus, Copyright Dennis Kunkel. The nucleus also controls the synthesis of proteins in the cytoplasm through the use of messenger RNA. Messenger RNA is produced in the nucleolus of the cell and travels to the cytoplasm through the pores of the nuclear envelope. Share Your Opinions What do you think about the nucleus of the cell? What are the advantages to having a true nucleus? Are there any disadvantages? Come on over to the Biology Forum and share your thoughts, opinions and feelings. Until next time... | |||||
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