The DNA strand that is complementary to the template strand copied by RNA polymerase during transcription has a nucleotide sequence identical to that of the RNA being synthesized (except T residues are found in the DNA strand at sites where U residues occur in the RNA). An RNA transcribed from this nontemplate DNA strand would be complementary to the mRNA synthesized by RNA polymerase. Such an RNA is called antisense RNA because its base sequence is complementary to the "sense" mRNA. One strategy to thwart the deleterious effects of genes activated in disease states (such as cancer) is to generate antisense RNAs in affected cells. These antisense RNAs would form double- stranded hybrids with mRNAs transcribed from the activated genes and prevent their translation into protein. Suppose transcription of a cancer-activated gene yielded an mRNA whose sequence included the segment \(5^{\prime}-\) UACGGUCUAAGCUGA. What is the corresponding nucleotide sequence \(\left(5^{\prime} \rightarrow 3^{\prime}\right)\) of the template strand in a DNA duplex that might be introduced into these cells so that an antisense RNA could be transcribed from it?

Step by step solution

01

Identify mRNA Sequence

The exercise provides the mRNA sequence as \(5^{\prime}-\)UACGGUCUAAGCUGA. mRNA substitutes Thymine (T) in DNA with Uracil (U), hence wherever there is U in mRNA, there will be A in DNA.

02

Determine the DNA complement

The sequence UACGGUCUAAGCUGA converts to its DNA complement ATGCCAGATTCGACT (considering A↔T and G↔C). However, this sequence corresponds to the non-template DNA strand, not the template strand.

03

Formulate Antisense DNA Template Strand

The template DNA strand is always antiparallel to the mRNA. So the sequence of the template DNA strand will be the reverse complement of the non-template strand. Thus, the template DNA strand (5' to 3' direction) is AGTCGATTCTGGCAT in order to form the given mRNA upon transcription and contribute to synthesizing the antisense RNA.

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