What is the complementary sequence to the DNA strand for 5’-GCTGATCAG-3’

Answer 1

To provide more context, in DNA, a purine always pairs with a pyrimidine. Purines are double-ringed structures and pyrimidines are single ring structures. I remember this because when I think of pyrimidine I like to think of a pyramid and they only have one base, hence one ring. Adenine(A) and Guanine(G) are purines. Thymine(T) and Cytosine(C) are pyrimidines. A always pairs with T and G always pairs with C. Also, it is good to note that the complementary sequence will be going the other way. For example, the original sequence is 5' to 3'. The complementary sequence will be in 3' to 5'. So with that mini-lesson, we can answer the question.

The complementary sequence is 3'-CGACTAGTC- 5'.