Helicases are the enzymes that help in unwinding both the strands of DNA for the process of DNA replication to take place. Other than DNA Polymerases, there are some enzymes that are also involved in DNA replication of Prokaryotes which play an essential role. As these strands do not have proofreading activity, therefore they produce mutated DNA even after a repair which is called as translation synthesis and adaptive mutagenesis. These two polymerases are involved in the DNA damage repair, i.e. 1 γ unit- This is the clamp loader which loads the clamp on the DNA strand.2 β units- It is the beta clamp which helps in joining the DNA pol 3 with DNA strand.Other than these subunits of core enzyme, following are some other parts and their role in the DNA pol 3: DNA polymerase III subunit θ- It acts as a stabilizer which stabilizes the activity of ε subunit.DNA polymerase III subunit ε- It has 5′ to 3′ exonuclease activity (proofreading).DNA polymerase III subunit α- It has role in replicating the DNA.These 3 subunits are responsible for following main functions: It is composed of a complex structure with alpha, epsilon and theta subunits in its core. This is the main replicating enzymes in prokaryotes which is mainly responsible for the synthesis of new DNA strands (5′ to 3′ polymerase activity) by bringing in new nucleotides. It has 3′ to 5′ exonuclease activity (proofreading).This gap-filling activity is utilized in filling the gaps between Okazaki fragments. It also has gap filling and DNA repairing activity.This activity is common in all types of DNA polymerases. It has 5′ to 3′ polymerase activity which is used for the synthesis of the DNA from 5′ to 3′ end.This is the exclusive activity of DNA pol 1. It has 5′ to 3′ exonuclease activity which is used for primer removal.If any error is detected, the DNA synthesis is halted until the error is rectified by the action of other enzymes. It has 3′ to 5′ exonuclease activity which is used for proofreading the daughter strand for any error in the addition of the nucleotides.This DNA polymerase has maximum activities which are listed below: Therefore while adding the new nucleotide, the DNA polymerase strictly follows Chargoff’s rule of base pairing and thus successful leads to the formation of new strands from the old (template) strand.įollowing are the 5 types of DNA Polymerase in Prokaryotes with their role This rule of base pairing is called as Chargoff’s rule. There is a fixed pattern of bonding between the nucleotides which is followed while adding the nucleotides on the growing end by the DNA polymerases. DNA polymerase, as the name depicts, is responsible for adding new nucleotides (dNTPs) to the growing end of the DNA strand. The main enzyme that works in DNA replication both in case of Prokaryotes and eukaryotes is DNA Polymerase, but there is structural and functional dissimilarity in both of the enzymes. Let us find out about these enzymes and their roles. Interestingly, there are different enzymes that are assigned different roles for each step. The main role in the process of DNA replication is played by the enzymes that catalyze this process. The process of DNA replication is different in eukaryotes and prokaryotes due to many factors like different enzymes are involved, different start and stop points, the difference in the structure of the DNA etc. The two strands are joined with each other by a series of hydrogen bonds between the bases of both the strands. It is composed of two strands of polynucleotides coiled with each other to form a helix. The DNA content is required to be doubled in order to divide it equally into both the daughter cells.ĭNA (deoxyribonucleic acid), as explained by Watson and Crick, is a double helix structure. This process of DNA replication takes place in the S-phase (synthesis phase) of the cell cycle right before the cell divides into two daughter cells. This is a fundamental process of all the living organisms having DNA as their carrier for genetic material. DNA replication is a process by which DNA makes copies of itself.
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