def transcribe_coding_strand(seq):
    """Given a coding strand in 5'-3' order, create the corresponding
       messenger RNA (also in 5'-3' order), assuming that the whole coding
       strand is translated and that the mRNA is not rearranged during
       transcription."""
    # Deal with both lists and strings
    if is_string(seq):
        sequence = seq
    elif is_list(seq):
        sequence = string.join(seq, '')
    else:
        parameter_error('transcribe_coding_strand', 1, "sequence", seq)
    # Do the real work
    result = sequence.replace('T', 'U')
    # Return the appropriate type
    if is_list(seq):
        return list(result)
    else:
        return result