Ribonucleic Acid

Ribonucleic acid (RNA) is a nucleic acid, like DNA, and is also made up of sugars, phosphates, and nitrogenous bases (or just a base). It contains a ribose sugar, whereas DNA contains a deoxyribose sugar. The four main bases found in RNA are guanine (G), cytosine (C), uracil (U), and adenine (A). DNA contains thymine (T) instead of uracil.

The ribose sugar of RNA gives it very different structural properties from those of DNA. RNA forms complex structures by folding a single strand upon itself. Ribose sugar makes RNA less stable than DNA, and it has to be produced often in a cell.

In most organisms RNA is made from their DNA. Some viruses, called retroviruses, contain RNA as their primary genetic material, for example, the AIDS virus and poliovirus.

There are many different kinds of RNA manufactured in a cell. Messenger RNA (mRNA) is produced to take the information contained in a specific segment of DNA and then use it to make proteins. Ribosomal RNA (rRNA) is part of a large RNA protein complex called the ribosome that binds mRNA and joins amino acids to make a protein. Transfer RNA (tRNA) brings amino acids to the ribosome and ensures that the amino acid used is in the order specified by mRNA. Many other kinds of RNA are also present in a cell. RNA plays an important role in the proper functioning of a cell.

SEE ALSO DNA REPLICATION; NUCLEIC ACIDS; PROTEINS.

Neena Grover

Bibliography

Berg, Jeremy M.; Tymoczko, John L.; and Stryer, Lubert (2002). Biochemistry, 5th edition. New York: W. H. Freeman. Also available from <http://bcs.whfreeman.com/biochem5/>.

Internet Resources

DNA from the Beginning. Information available from <http://www.dnaftb.org/dnaftb/>.

"DNA: The Instruction Manual for All Life." The Tech. Available from <http://www.thetech.org/exhibits_events/online/genome/>.

"Structure of RNA." Molecular Biology Notebook Online. Available from <http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/rnast.htm>.