|MadSci Network: Cell Biology|
Candy: To understand how a cell makes protein, you'll need to know about (1) three very important molecules, and (2) three basic steps. Three very important molecules: 1. DNA 2. RNA 3. Ribosome Three basic steps: 1. Gene transcription 2. RNA export 3. RNA translation How do these fit together? As you mentioned, protein synthesis starts in the cell's nucleus. (Some of my scientist friends would want me to mention that prokaryotes, such as bacteria, have no defined nucleus, but their protein-making process is similar to what we'll discuss here. To keep things simple, we'll stick with eukaryotic cells -- the ones that do have nuclei. But if you want to know the difference between prokaryotes and eukaryotes, you can find out at The Biology Project website.) The instructions for making a protein are found within the nucleus, in the cell's DNA -- in the form of genes. Through a process called gene transcription, the information contained in the DNA is transferred to a molecule called RNA, which shares a similar chemical makeup with DNA. RNA is exported from the nucleus to the cytoplasm with the help of specific protein machinery. Once in the cytoplasm, the RNA is decoded -- or translated -- by ribosomes, which use the decoded information to make a protein chain out of single amino acids. Can you think of a good reason why a cell might need RNA to carry information from DNA to the ribosome? Here's a hint.) For me, pictures help make things more clear. I found a good one on this page. My scientist friends would also want me to tell you that while I've covered the basics here, DNA transcription and translation are far more complex than I've described. Follow the links from this page for a more detailed description of the transcription/translation process. Best, Jennifer Jennifer Logan, Ph.D. Genetic Science Learning Center Eccles Insitute of Human Genetics University of Utah
Try the links in the MadSci Library for more information on Cell Biology.