In the process of transcription a DNA molecule uncoils at a point along its structure where the neccessary information to construct the needed protein is. The weak hydrogen bonds between the DNA bases then break, using the neccessary enzymes, which opens the molecule out, then free RNA nucleiotides in the nucleus combine with their complementary bases on one side of the DNA it is not important which side it joins with as they both contain the same information. As RNA has no thymine the DNA's adenine combines with the RNA's uracil instead the o ....