Select the correct 18mer 18 bases long reverse primer to amp

Select the correct 18mer (18 bases long) reverse primer to amplify the DNA sequence comprised between the two bases indicated in red color and underlined. 5\'GAATTCATGCGTAGATCGATGATCATGATGCGATGATGATGATGATGCCGTATAGATGTATAAATGATA GATT TGACACGCATATAGACATAGTGGATTGGGATAGATCGTGATGATG TCTCTCGATTTAGGTAT TAGATGTAGGATAGATTCCCGGG 3\' REVERSE PRIMER GAATTCTATCCTACATCTA GAATCTATOCTACATcTAAAA e GAATcccTACATCTA o GAATTTATOCTACATOTA. o TTATCTATOCTACATCTA GAATGGGGCCTACATCTA GAATCTATCCTACATCTA GAATCTATCCTACATCTATTTT

Solution

Answer 1 - For a reverse primer, we need to reverse the sequence. Hence the 5\' end becomes 3\' and 3\' becomes the new 5\' end. Starting from the 5\' end of this reversed sequence, start writing the complementary strand sequence. The complementary strand sequence up till 18 base pairs will serve as your reverse primer; which in this case comes out to be as - Option \"e\" - 5\' GAATCTATCCTACATCTA 3\'