Upstream/downstream

Name:
Upstream/downstream
Detailed information:
In an RNA, anything towards the 5′ end of a reference point is “upstream” of that point. This orientation reflects the direction of both the synthesis of mRNA and its translation—from the 5′ end to the 3′ end. In DNA, the situation is a bit more complicated. In the vicinity of a gene (or in a cDNA), the DNA has two strands, but one strand is virtually a duplicate of the RNA, so its 5′ and 3′ ends determine upstream and downstream, respectively.Note: that in genomic DNA two adjacent genes may be on different strands and thus oriented in opposite directions. Upstream or downstream is only used on conjunction with a given gene.