The Polarity of DNA Synthesis Is

Question

The polarity of DNA synthesis is
A) 5'→3'
B) 3'→5'
C) 5'→2'
D) 2'→5'
E) None of the choices are correct.

Accepted Answer

DNA synthesis occurs in the 5'→3' direction, meaning that nucleotides are added to the 3' end of the growing strand. This polarity arises because the 3' end of the DNA molecule has a free hydroxyl group (-OH) while the 5' end has a free phosphate group (-PO4), and the incoming nucleotide is always added to the 3' hydroxyl group of the previous nucleotide. Therefore, choice A is the correct answer.