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I've always thought that the majority of the "work" in a cell is protein production, until I read the following.

The Wikipedia article on the central dogma of molecular biology states this:

80% of the human genome is transcribed even though only 1% codes for proteins.

and this:

Current research focuses on investigating the function of non-coding RNA, that is, RNA that does not follow the dogma trend and does not code for polypeptides.

If 99% of what's transcribed isn't used for creating proteins, what is it used for? If it's not known - are there any hypotheses?

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in short, some of it is regulatory, like miRNAs, and a bunch of it we don't really know why... – MattDMo Jun 30 '13 at 0:21
...and of course, even regulatory RNAs are ultimately concerned with the core activity of "creating proteins". – Alan Boyd Jun 30 '13 at 7:40
...and from another angle, red blood cells don't make any proteins. – Alan Boyd Jun 30 '13 at 11:27
So what do the Ribosomes do in red blood cells? – PeteGO Jun 30 '13 at 12:49
Red blood cells lose their ribosomes when they develop from reticulocytes. My comment was only meant to point out that not all cells are typical. – Alan Boyd Jun 30 '13 at 15:07
up vote 4 down vote accepted

As indicated in the comments there are several non-coding (untranslated) RNAs, that the cell produces. Most of these perform gene regulatory functions. However, widespread transcription is known to take place throughout the genome (pervasive transcription), but the functions of these RNAs are not clearly understood. It has been suggested that in certain cases the event of transcription, rather than its product, is responsible for chromatin regulation.

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Untranslated RNA is incredibly important. As mentioned it regulates gene control, siRNA or miRNA for example can cut up mRNA preventing it being translated. Others can cause an increase in expression like enhancer RNA. Then RNA can act as tRNA or ribosomal RNA in protein translation. RNA can be enzymatically active, RNA also acts as a primer for initiation of replication. Then theres retroviruses that have inserted into our genome but have lost the ability to exit and are now part of our genome: the endogenous viruses. There are genes that are redundant duplications of functional genes that are free to evolve. As mutations occur silent parts may regain the ability to be transcribed.

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When cells are not producing proteins they are performing their specialized functions. Consider red blood cells carrying oxygen. Or gut epithelial cells aiding in your digestion. The list goes on...liver cells have a different role than the keratin cells in your hair. There is a lot of transport that goes on as well in an certain cells that is carried out by motor proteins such as myosins, kinesins, and dyneins. Cells are producing ATP to power these motors and many other integral functions. Also, consider cell replication and the machinery needed for that to occur.

You may visit Wikipedia for more information on motor proteins.

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