DNA contains all the information needed to maintain a cell's processes, but these precious blueprints never leave the protected nucleus. How, then, is all this data transmitted to the body of the cell itself where it may be put to use? The answer: by way of RNA. The three types of ribonucleic acid (mRNA, tRNA, and rRNA) allow for the communication and translation of genetic information outside of the nucleus.

RNA is a long polymer similar to DNA. The differences are as follows:

1. The five carbon sugar in RNA is ribose, while in DNA it is deoxyribose
2. In place of thymine, RNA uses the nitrogenous base uracil (thus the possible pairs become C-G and A-U)
3. While DNA is a double-helix, RNA is almost always a single stranded molecule
4. RNA is significantly shorter than DNA
5. DNA is more stable than RNA

Transcription

Transcription in Action

For an RNA molecule to be created, it must be synthesized from a segment of DNA through a process called transcription. To begin this process an enzyme called RNA polymerase binds to a specific area on a DNA molecule called the promoter. The promoter signals the beginning of a genetically coded message, or gene. The RNA polymerase, upon encountering the promoter that it was looking for, begins to unwind the DNA double helix. As the helix unwinds an RNA strand is created in the exposed area (this is similar to DNA replication, explained earlier). The RNA is then disconnected from the DNA and the helix is reconnected. This system of unzip, encode, and re-zip continues along the gene until the RNA polymerase encounters a termination signal and the new molecule is complete. Usually, this process can occur to a single gene many times simultaneously if it is in demand, the unzipping enzyme associated with one future RNA molecule would follow the re-zipping portion of another, and so on.