[Campbell Biology P.368] A specific DNA strand has the sequence 5'-TGCATTCGCCAATTA-3'. Consi... | Practice Question

A specific DNA strand has the sequence 5'-TGCATTCGCCAATTA-3'. Considering the antiparallel nature of DNA, which of the following represents its complementary strand?

  • A: 5'-ACGTAAGCGGTTAAT-3'
  • B: 3'-TGCATTCGCCAATTA-5'
  • C: 3'-ACGTAAGCGGTTAAT-5'
  • D: 5'-AATTGCGGAACTAGT-3'

Explanation

DNA strands are antiparallel, meaning they run in opposite directions. If the given strand is 5'-TGCATTCGCCAATTA-3', its complementary strand must be read from 3' to 5' when written 5' to 3' for clarity . Following base pairing rules A with T, G with C , the complementary sequence for TGCATTCGCCAATTA is ACGTAAGCGGTTAAT. Since the original is 5' to 3', its complement will be 3' to 5' in orientation, thus 3'-ACGTAAGCGGTTAAT-5'.