What term describes the arrangement where the two DNA strands run in opposite directions?

What term describes the arrangement where the two DNA strands run in opposite directions?

• A. Parallel arrangement
• B. Complementary arrangement
• C. Antiparallel arrangement
• D. Symmetric arrangement

Answer: (C)

Two DNA strands are antiparallel, meaning they run in opposite directions along the helix. Each strand has a distinct orientation with a 5' end and a 3' end, so one strand runs 5' to 3' while the other runs 3' to 5'. This arrangement allows proper base pairing (A with T, G with C) and accommodates DNA polymerases, which synthesize DNA by adding nucleotides to the 3' end in a 5' to 3' direction. If the strands ran in the same direction, the geometry and enzymatic mechanisms wouldn’t align for accurate replication. So the term that describes this opposite-direction arrangement is antiparallel.

Two DNA strands are antiparallel, meaning they run in opposite directions along the helix. Each strand has a distinct orientation with a 5' end and a 3' end, so one strand runs 5' to 3' while the other runs 3' to 5'. This arrangement allows proper base pairing (A with T, G with C) and accommodates DNA polymerases, which synthesize DNA by adding nucleotides to the 3' end in a 5' to 3' direction. If the strands ran in the same direction, the geometry and enzymatic mechanisms wouldn’t align for accurate replication. So the term that describes this opposite-direction arrangement is antiparallel.