The Cell Nucleus

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I Introduction The Nucleus, let’s think of it like the brain of the cell, it controls all the activity in the cell like for example the movement, the reproduction, eating, etc. Is the largest organelle in the cell. The nucleus is mostly in the center of the cell but it can be somewhere in the middle of the cytoplasm. The Nucleus is always surrounded by a nuclear membrane which protects the Nucleus from the other cell parts. Now in order to explain the Nucleus we need to explain the cell types. Since not all the cells have a nucleus the biologist divided the cells in eukaryotic cells and prokaryotic cells. Eukaryotic cells have a defined nucleus with all of its components and Prokaryotic cells do not have a defined nucleus. Now we know chromatin and DNA are in the nucleus so, Does a Prokaryotic cell have DNA? Yes, the cell do have a DNA the only difference is that in a Prokaryotic cell the DNA is probably floating in the “nucleoid” (Only the Prokaryotic cells have a nucleoid which is the area where genetic material is found.).

Inside the nucleus The nucleus have 4 inner parts. Nuclear Pore: The nuclear pore is a protein-line that helps “regulating” the transportation of molecules between the cytoplasm and the nucleus. In other word the nuclear pore helps to regulate the communication between the nucleus and the cytoplasm Nuclear Envelope: The nuclear envelope is like a two-layer membrane that envelope the nucleus (only of Eukaryotic cells.). Nucleolus: The nucleolus is a secondary organelle that administrates subunits to form ribosomes. The Nucleolus can change its size basing in ribosomal requirements. In other words if a cell produces huge amounts of protein and thus call for big amounts of ribosomes the nucleolus will have a greater size or the opposite, if the cell produce low amounts of protein and thus call for low amounts of ribosomes the nucleolus size would be smaller. Chromatin: The chromatin seen with naked eye is like a tiny granular material, but what it does is that carry “strands” of protein and DNA. It is made of DNA, Nuclear protein and RNA. DNA and RNA are nucleic acids 2

that are inside the cells so when the cell is ready to divide the chromatin condenses to form chromosomes. (Chromosomes are structured chain of DNA and nuclear protein and this are the one in charge of transmitting the genetic information “from one generation of cells to the next” So if you take a nucleus of a cell and insert it in a new cell, the new cell will follow the instructions of the old-cell, this is how scientist do cloning.

Conclusion The nucleus is one of the most important organelles in the cell because inside of it holds the Nucleic Acids (DNA and RNA) which makes possible the reproduction, it holds chromatin which forms chromosomes which are the ones in charge of the hereditary information. DNA replication processes take place inside the nucleus without saying that it stores all the information that is to be transferred to the next generation. The information generated by nucleus governs the formation of enzymes and other proteins that carry out all the processes of body.

Bibliography RADER’S BIOLOGY4KIDS, [online] [consulted: 15 October 2009]. Available in: < http://www.biology4kids.com/index.html>. SCITABLE, by nature education [online] [consulted: 15 October 2009]. Available in: < http://www.nature.com/scitable>. KIDIPEDE, [online] [consulted: 15 October 2009]. Available in: < http://www.historyforkids.org/>.

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