DNA synthesis takes place in which direction?

DNA synthesis occurs in the 5' to 3' direction due to the enzymatic mechanism involved in the addition of nucleotides to a growing DNA strand. During DNA replication, DNA polymerase, the enzyme responsible for synthesizing new DNA strands, can only add nucleotides to the 3' end of an existing DNA or RNA strand. Because nucleotides are added to the 3' hydroxyl group of the last nucleotide, the strand elongates towards the 5' end of the template strand.

This directionality is critical for the accuracy of DNA replication. The antiparallel nature of DNA strands means that one strand runs in a 5' to 3' direction while the complementary strand runs 3' to 5'. This orientation affects various processes like replication and transcription in the cell.

Understanding this concept is vital in molecular biology, as it underpins the mechanisms of DNA replication, which is essential for cell division and maintenance of genetic information across generations.