downstream

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Cardiology The direction of blood flow, specifically in vessels flowing from the heart
Molecular biology A position on a molecule of interest—e.g., protein or DNA—that is ‘beyond’ or in front of a reference point; the term downstream differs according to the system involved

downstream

In genetics, at a stage in the sequence of processes in the expression of a gene that is nearer the final protein product than any stage in the direction of the DNA. The term is also used to mean in the direction of the 3'-end of a chain of bases in DNA (see PHOSPHODIESTER BOND). In both cases the opposite sense is called ‘upstream’.

downstream

(of a LOCUS on a DNA MOLECULE) relating to a position in the direction in which TRANSCRIPTION occurs, often after the transcription start site in DNA and towards the last coding region to be transcribed. By convention the DNA sequence of genes is shown from 5' (left) to 3' (right) so that ifX is on the 3' side of Y it is described as being downstream of Y. Compare UPSTREAM.