Which sequence represents the complementary strand of the DNA sequence ATGGCT?

Which sequence represents the complementary strand of the DNA sequence ATGGCT?

• A. AGGCTA
• B. TACCGA
• C. CTGCGT
• D. TACCGT

Answer: (B)

DNA pairs form only with A and T or with G and C, and the strands are opposite each other in the double helix. To find the complementary strand, replace each base with its partner: A pairs with T, T with A, G with C, and C with G. Doing this for ATGGCT, you get T A C C G A, which is TACCGA. This sequence can align with the original strand through hydrogen bonding to form the standard double-stranded DNA. The other sequences don’t follow the base-pairing rules at every position, so they aren’t the correct complementary strand.

DNA pairs form only with A and T or with G and C, and the strands are opposite each other in the double helix. To find the complementary strand, replace each base with its partner: A pairs with T, T with A, G with C, and C with G. Doing this for ATGGCT, you get T A C C G A, which is TACCGA. This sequence can align with the original strand through hydrogen bonding to form the standard double-stranded DNA. The other sequences don’t follow the base-pairing rules at every position, so they aren’t the correct complementary strand.