PCAT Review Questions - Pharmacy College

Answer: D, The complementary base strand to the sequence AGCGTATTGCG is TCGCATAACGC. In DNA, adenine pairs with thymine and guanine pairs with cytosine.

Key Takeaway: The pairing of nitrogenous bases in DNA was first described in the Watson-Crick base pairing model, which also described the double-helix structure of DNA. This model accounts for the fact that in numerous organisms, adenine and thymine are always present in DNA at the same amounts, as are guanine and cytosine. In DNA, the paired bases are bound together by hydrogen bonds.