Answer:
3'-GCTATAACTCGATTCGAA-5'
Explanation:
The DNA is a macromolecule formed by two strands of polynucleotides forming a double helix.
These chains are composed of monomers called nucleotides, there are 4 different types in DNA, called nitrogenous bases: two purines, guanine (G) and adenine (A) and two pyrimidines, thymine (T) and cytosine (C). They are joined by covalent bonds in each chain.
These bases are complementary: G with C, and A with T between the two strands by hydrogen bonds making the double-stranded DNA molecule.
A sequence 5'-CGAT-3' is equivalent to a sequence written 3'-ATCG-5' , because the 5' and 3' notation defines the direction of reading. If one strand is noted 5' to 3', then the complementary strand will be from 3' to 5' in the same sense.
So, all we need to do is write the complementary bases from the 3' end to 5':
5'-CGATATTGAGCTAAGCTT-3'
3'-GCTATAACTCGATTCGAA-5' (answer)