Question

With respect to which strand are all coordinates such as 'upstream' and 'downstream' defined in a transcription unit?

Options

• Coding Strand

• mRNA strand

• Template Strand

• Either strand equally

Answer 1

All directional coordinates in a transcription unit, including upstream (toward 5') and downstream (toward 3'), are defined with respect to the Coding Strand. This convention exists because the Coding Strand has the same sequence as mRNA (except T → U) and serves as a reference for describing the orientation and position of transcription unit components.