Q: What is 5' (5 prime) in DNA?

Flexi Says: The terms 5' (5 prime) and 3' (3 prime) indicate certain carbon atoms of the pentose sugar present in the sugar-phosphate backbone of the nucleic acids (DNA and RNA). The 5' carbon is attached to a phosphate (PO₄^-) group, and the 3' carbon is attached to a hydroxyl (-OH) group.