DNA has an antiparallel arrangement of its two nucleotide strands

 

What Does "Antiparallel" Mean?

• DNA consists of two complementary strands running in opposite directions.
• One strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction.

How is this arrangement structured?

• Each nucleotide has a phosphate group (5' end) and a hydroxyl group (-OH) on the 3' carbon (3' end).
• The 5' end of one strand aligns with the 3' end of the other strand, creating an antiparallel configuration.
• This orientation allows complementary base pairing (A-T and G-C) and proper DNA replication and transcription.

Why is the Antiparallel Arrangement Important?

1. Enables Complementary Base Pairing – A pairs with T, and G pairs with C through hydrogen bonds.
2. Facilitates DNA Replication – DNA polymerase can only add nucleotides in the 5' to 3' direction, requiring a leading and lagging strand mechanism.
3. Ensures Stability – The antiparallel structure contributes to the double helix stability and proper packing in cells.

This antiparallel arrangement is essential for DNA function, including replication, transcription, and overall genetic stability.