What does DNA replication involve in terms of directionality?

DNA replication is a process that entails synthesizing a new strand of DNA complementary to an existing strand. The directionality of DNA refers to the orientation of the nucleotide strands, which is denoted by the 5' (five-prime) and 3' (three-prime) ends of the DNA molecule.

During DNA replication, the new strands are synthesized in a specific direction: from the 5' end to the 3' end. This means that DNA polymerase, the enzyme responsible for adding new nucleotides, can only add nucleotides to the 3' end of the growing strand. However, DNA strands are antiparallel, so the two strands of the double helix run in opposite directions.

In the context of the leading and lagging strands, the leading strand is synthesized continuously in the direction of the replication fork, which is from the 5' to the 3' direction. Conversely, the lagging strand is synthesized in a discontinuous manner, producing short segments called Okazaki fragments. These fragments are formed in the 5' to 3' direction, but since the lagging strand runs in the opposite direction relative to the replication fork, it ultimately has to be synthesized in a