DNA Replication: The Basis of Life

DNA replication is an important process that takes place in all living organisms. It is through DNA replication that all of our biological information gets copied into the DNA our cells use for functioning. The process itself takes place at the origin of replication in a cell. We all know that DNA is a double stranded molecule and both strands of combine together to form the double helix of the molecule.  However, during replication, the strand to be synthesized gets unfolded at the replication forks. The process of DNA replication starts from one double stranded molecule, which is used as a template strand to make the complementary strand and so on. The main strand is used as a guide to replicate the complementary strand. Each strand is composed of four nucleotides that have the basses Adenine, Thymine, Guanine and Cytosine. The base adenine (A) is always paired with thymine (T) and guanine (G) is always paired with cytosine (C), they get connected via hydrogen bonds between them. The entire DNA is synthesized from the 3’ prime to the 5’ prime direction. The two strands of the DNA run anti parallel so they always combine in the opposite directions, the 3’ prime end is always paired with the 5’ prime end of the second strand and the same goes for the other side.

            Many enzymes play an integral role in carrying out the DNA replication process. DNA polymerases are part of the enzymes that help carry out the replication process. DNA polymerase is only able to add nucleotides on to the 3’ end of the DNA strand. It is unable to carry out the synthesis of a new strand on its own without a template strand and it only starts the synthesis process when a primer, a piece of RNA, gets added to the template strand. After the primer gets added, the DNA polymerase starts the replication process by adding nucleotides to the complementary strand opposing the template strand. As the nucleotides are added, the DNA polymerase removes two phosphates form the DNA strand. The energy from removing two phosphates from the DNA strand is used to create phosphodiester bonds that connect the nucleotides together.

            Overall, the process of DNA replication is very accurate. It has its own proofreading system. DNA polymerase itself has the ability to proofread DNA replication. If in case there is a mismatch in nucleotide paring, it is able to remove one base pair to fix the mismatch. Therefore DNA replication is usually exact duplication of the template DNA strand and it’s the same thing being replicated over and over again.