DNA is a molecule that carries genetic information in living organisms, it contains bases ( A, T, C, G ), phosphate groups and a deoxyribose sugar. The bases in the DNA molecule pairs such that A pairs with T while C pairs with G to form base pairs that are joined to the phosphate group and the deoxyribose sugar. Therefore, the complementary DNA sequence of the following segment (CTG GAA CTA ) will be GAC CTT GAT.