What is meant by position 5' or 3' [closed]








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I'm a self-learner that likes to keep up with current research. However, I can't find what is meant by expressions such as 5' or 3' positions on chemical structures. But , in particular, what is meant by the phrase "Cis-elements may be located in 5' or 3' untranslated regions or within introns." 




Here is a link to a more than half-decent biochemistry textbook chapter explaining the numbering: <https://www.ncbi.nlm.nih.gov/books/NBK22490/>


And the relevant figure from that chapter:


[![enter image description here](https://i.stack.imgur.com/qwRu0.jpg)](https://i.stack.imgur.com/qwRu0.jpg)



> 
> [Berg, Tymoczko, Stryer] Backbones of DNA and RNA. The backbones of these nucleic acids are formed by 3′-to-5′ phosphodiester linkages. A sugar unit is highlighted in red and a phosphate group in blue. 
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Like any other linear polymer sucu as proteins and DNAs, RNA structure has two ends. Like carboxylic acid end and amine end notation given for proteins, two ends of a RNA (and DNA) call 3'-end and 5'-end (see the diagram below): 


[![RNA Structure](https://i.stack.imgur.com/4fsu2.jpg)](https://i.stack.imgur.com/4fsu2.jpg)


Note that these notations are derived from the numbering of the ribose sugar function (see the 5'-end of the tetramer in the diagram).


Answer for your particular question: What is meant by the phrase "Cis-elements may be located in 5' or 3' untranslated regions or within introns"?, see diagram below:


[![untranslated region](https://i.stack.imgur.com/cxach.jpg)](https://i.stack.imgur.com/cxach.jpg)


Cis-regulatory elements (CREs) such as promoters, enhances, silencers, etc. are usually in 5' or 3' untranslated regions.


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