Snapshot: What is RNA?

RNA is an important molecule that helps with regulating the function of cells. To fully understand how RNA fits in here, we must first look at the bigger picture: genetics. The central dogma of molecular biology, depicted below, states that DNA is copied (transcribed) into RNA, which is later decoded (translated) into proteins, which perform many vital functions in the cell. So, when the cell needs a specific protein, it locates the stretch of DNA that contains the code for this protein and starts to write a copy of that stretch of DNA. This copy is made using RNA, or ribonucleic acid, as a backbone. RNA is very similar to DNA, but contains one extra oxygen atom in the basic building block. Only one strand of the DNA is copied, so RNA ends up looking like half a DNA molecule. The RNA molecule can be seen as the messenger between the archive of your genes (DNA) and the protein production site. However, RNA is very versatile and is also involved in protein regulation, transport of molecules and as a structural component of large complexes in the cell.

The "central dogma" of molecular biology: DNA makes RNA, then RNA makes protein.
The “central dogma” of molecular biology: DNA makes RNA, then RNA makes protein. Adapted from Wikimedia.

The shifting stream of RNA

Apart from small random mutations during the course of a lifetime, the DNA contained in every cell remains the same from birth to death. However, since different cells need different proteins at different stages of growth, there needs to be a selection of which genes are copied and translated into proteins. This means that the process of making RNA has to be very flexible. This flexibility is achieved through a large network of signals that tell the cell which regions of DNA should be transcribed into RNA, and at what rate. To keep up with the demands of the cell, there are millions of RNAs being made at all times, to send out instructions to makes proteins.

How can RNA cause disease?

In some spinocerebellar ataxias, such as e.g. SCA8, the messenger RNA molecules contain long repetitive sequences that become sticky to other copies of the same RNA or to proteins, forming both small and large clumps in the cell. There is still controversy surrounding which steps in the process that ultimately causes cell death in large brain areas, but it seems that unsolicited binding of these sticky RNAs to proteins and other RNAs causes disruption to several functions in the cell simultaneously. Therefore, many researchers are hopeful that reducing the amount of these RNAs in the cell using Antisense Oligonucleotides or RNA interference can help treat spinocerebellar ataxias and other similar diseases.

If you would like to learn more about RNA, take a look at these resources by the Encyclopedia Britannica and Khan Academy.

Snapshot written by Frida Niss and edited by Dr. Hayley McLoughlin.