What is meant by anti-parallel orientation in DNA?

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Multiple Choice

What is meant by anti-parallel orientation in DNA?

Explanation:
Anti-parallel orientation means the two DNA strands run in opposite directions along the same helix: one strand goes from 5' to 3' while the other runs from 3' to 5'. This arrangement comes from the way nucleotides are built—with a phosphate on the 5' end and a OH on the 3' end—and from the way DNA polymerases add new nucleotides to the 3' end, so synthesis proceeds 5' to 3'. Because the strands are opposite, base pairing is properly aligned and replication can occur on both strands: the leading strand can be synthesized continuously toward the fork, while the lagging strand is made in fragments away from the fork. The idea that the strands run in the same direction or that they’re perpendicular doesn’t fit the actual structure of DNA.

Anti-parallel orientation means the two DNA strands run in opposite directions along the same helix: one strand goes from 5' to 3' while the other runs from 3' to 5'. This arrangement comes from the way nucleotides are built—with a phosphate on the 5' end and a OH on the 3' end—and from the way DNA polymerases add new nucleotides to the 3' end, so synthesis proceeds 5' to 3'. Because the strands are opposite, base pairing is properly aligned and replication can occur on both strands: the leading strand can be synthesized continuously toward the fork, while the lagging strand is made in fragments away from the fork. The idea that the strands run in the same direction or that they’re perpendicular doesn’t fit the actual structure of DNA.

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