Question: Does the "free arm" of deoxyribose point in the direction in which the coding strand is read, or against it?

Ditte Hedegaard answered on 27 Jun 2014:

The DNA double helix consist of two complementary strands each strand will have a carboxyl group attached to one end and an amine group attached to the other. These are also called the 3-prime (3′) end and the 5-prime (5′) end. I’ve tried drawing it underneath

5′ – ATCCTGATTGT- 3′
3′ – TAGGACTAACA-5′

In order to activate the genes and make proteins from them, the DNA double helix has to be separated into 2 strands so that the nucleotides guanine (G), adenine (A), thymine (T) and cytosine (C), which makes up the genetic code, are free and available for activation. After the 2 strands have been separated proteins in the cell will start reading the code and make a copy of it in RNA. Only one of the strands will be read because the RNA strand required for making new proteins only have one strand. The strand that is copied is called the template strand. The protein making the RNA copy is called the RNA polymerase, it prefers copying the gene from the 3′-end to the 5’end. Dependent on which direction the RNA polymerase is going (left to right or right to left) it may either be the top DNA strand or bottom DNA strand which is copied. , This process of copying DNA into RNA is also called transcription and you can see a video about it here http://www.youtube.com/watch?v=5MfSYnItYvg&index=3&list=PL36B7A3A524C70184