Explanation:
First, think about which base pairs arise in complementary strands of DNA:
DNA → DNA
adenine → thymine (A → T)
thymine → adenine (T → A)
cytosine → guanine (C → G)
guanine → cytosine (G → C)
However, mRNA does not consist of the same four bases as DNA. While DNA has the ATCG nitrogenous bases, RNA replaces thymine with uracil, making its bases AUCG.
So, that means that whenever DNA has adenine, instead of pairing this with thymine, RNA will use uracil instead.
DNA → RNA
adenine → uracil (A → U)
thymine → adenine (T → A)
cytosine → guanine (C → G)
guanine → cytosine (G → C)
Giving us the corresponding sequence:
