Structure of a Cell - Fragilex.org


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What is the Structure of a Cell and How Does it Make Proteins?

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Dennis Kunkel's Image Gallery
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All living things are made up of cells, the small working units of life. Cells are small; it would take a row of 3 or 4 red blood cells to go from one edge of a human hair to the other edge.

Each cell works somewhat like a factory. The external membrane functions as the exterior walls of the factory. The nucleus stores the genetic blueprints in the form of DNA. The machinery (ribosomes) for assembling the products (proteins) is attached to the shop floor (endoplasmic reticulum). The Golgi concentrates the proteins to export them. The lysosome is used for waste disposal and recycling.

Copyright
Dennis Kunkel's Image Gallery
Used with permission

The synthesis of a protein such as FMRP (fragile X mental retardation protein) begins in the nucleus of the cell when the DNA receives a request for that specific information. It is a bit like someone going to a library and selecting a particular book. In response to the request, the DNA opens up and a copy of the coded information is transcribed, much like someone photocopies a chapter of a book in a library. That copy of the DNA is called messenger RNA (mRNA).

The mRNA leaves the nucleus and goes out to the main part of the cell, the cytoplasm. There the coded mRNA is translated on ribosomes with the help of transfer RNA and a protein is assembled out of amino acids.

The protein takes on a particular shape that allows it to perform very specific tasks. While we know the tasks of some of the proteins that humans make, we only have hints about the role of FMRP.